# Questions and Coding

The COVID-19 Trends and Impacts Survey (CTIS) has been deployed in several waves. We have tried to ensure the coding of waves is consistent. This page provides the full survey text, coding schemes, and history of survey waves and revisions.

Comprehensive documentation: The CTIS Methodology Report describes the sampling, data collection, and weighting process. Our codebook (CSV) lists all questions and answer choices across all waves of the survey. See below for details on the basic coding rules and the formatting of the codebook, and narrative explanations of the reasons for each instrument change.

1. Basic Coding Rules
2. Comprehensive Codebook
3. Wave 1
4. Wave 2
5. Wave 3
6. Wave 4
7. Wave 5
8. Wave 6
9. Wave 7
10. Wave 8
11. Wave 9
12. Wave 10
13. Wave 11
1. New Items
2. Changed Items
3. Removed Items
4. Notes
14. Wave 12
15. Wave 13

## Basic Coding Rules

All response choices are recorded numerically starting from 1, in displayed order from left to right and top to bottom. When the respondent is allowed to select multiple responses, these are shown separated by commas, such as 2,4,6. Questions left blank or with invalid responses are recorded in the CSV files as NA.

Timestamps are provided in Pacific time (UTC-7). The following metadata columns describe each survey response:

• StartDatetime: The time the respondent began the survey.
• EndDatetime: The time of the last activity by the respondent on the survey. If they submitted the survey, this is the time it was submitted. If the user did not complete the survey, their response may have been recorded automatically after a timeout; this is the time of their last activity, not of the recording. See the response files documentation for details on the automatic recording of responses.
• weight: The survey weight calculated by Facebook, for demographically adjusting estimates. See the weights documentation for details on how to use these weights.

The following columns were added beginning when Wave 4 was deployed:

• wave: Integer specifying the survey wave this respondent completed; see below for the full list.
• UserLanguage: Language the respondent completed the survey in.
• fips: The primary county FIPS code corresponding to the ZIP code selected by the respondent. Note that ZIP codes can cross county and even state boundaries; if a respondent’s ZIP is in multiple counties, the FIPS reported in this column corresponds to the county the ZIP overlaps most with. If a ZIP is not more than 50% in any one county, or if their reported ZIP code cannot be found, NA is reported.

Beginning in Wave 11, the module column indicates which module the respondent was randomly assigned to. See the survey modules and randomization information for more details.

### Privacy Restrictions

To prevent respondents from being identifiable in the response data, responses with ZIP codes with populations of 100 or fewer have their location set to NA. This affects item A3 in the individual response files. (This change was implemented with the introduction of Wave 4. Previously, all ZIPs were reported.)

Invalid ZIP codes are preserved unchanged, and these rows are reported in the individual response files with their invalid ZIPs.

### Race and Ethnicity

Beginning in wave 4, items D6 and D7 ask respondents for race and ethnicity. These columns are not available in the microdata files due to reidentification concerns. Public contingency tables that aggregate by race and other demographic variables are available.

Users with a specific need for these variables in microdata should contact us at delphi-survey-info@lists.andrew.cmu.edu to discuss options for obtaining them, as access can be provided under some restrictions.

In the contingency tables, and in the microdata files for users who have gained permission to access this data, the raceethnicity column is coded based on the following rules:

• If the respondent answers “Yes” to item D6, they are coded as Hispanic, regardless of their answer to D7. If the respondent answers “No” to D6, the following rules apply.
• Respondents who selected more than one racial group in D7, or who selected “Some other race”, are coded as “NonHispanicMultipleOther”.
• Respondents who selected only one racial group in D7 are coded according to that race, such as “NonHispanicAsian” or “NonHispanicAmericanIndianAlaskaNative”.

## Comprehensive Codebook

The codebook (CSV) describes availability of metadata and question fields by survey version. A row is included for each field available in the microdata files for a given survey wave. We recommend using the codebook as a reference while working with the survey microdata, to ensure you interpret each question and answer choice accurately even as items were revised between survey waves.

If a field is available for multiple waves, it is listed separately for each version. Items that were included in non-contiguous survey waves have entries only for those waves that they appeared in, with interceding waves not listed.

Values are missing (NA) for columns not relevant to a given field. For example, metadata fields do not correspond to survey items and thus do not have question text or answer choices defined.

Available columns:

• version: Integer specifying the survey version (“wave”) that field is available for or item was asked in.
• variable: Field name as it appears in the microdata. For most survey items, this corresponds to question name. Each subquestion of a matrix item is listed seperately. For these, variable is the question name followed by the subquestion number, e.g. A1_3 for the third subquestion of item A3.
• qid: Unique identifier of the format QID<number> assigned by Qualtrics to each survey item.
• matrix_base_name: For matrix items, the question name without the subquestion indicated.
• replaces: Question name of previous version of survey item, if any. Different versions of a given question may vary in wording, referenced time frame, or in other ways; refer to item text for specfics.
• description: Brief description of the meaning of a field or survey item.
• question: Survey item text.
• matrix_subquestion: Subquestion text for a matrix item.
• response_options: JSON-formatted map of answer codes and response choice text. For example, "5": "California" means that responses with the value 5 correspond to the respondent selecting “California”.
• question_type: Survey item format; one of “Matrix” (several questions with the same question stem are displayed together with the same answer choices), “Text” (free text entry), “Multiple Choice” (particpant can select only one answer choice), or “Multiselect” (respondent can select one or more answer choices).
• display_logic: Conditions a respondent has to satisfy to be shown an item. For example, this can require a specific answer on a single previous item or a set of previous items, or that a previous item was displayed.
• response_option_randomization: How answer choices are displayed for a given question. Answer choice order can be fixed (“none”), reversed (“scale reversal”, e.g. for Likert scales) or shuffled (“randomized”) between respondents.
• respondent_group: Module-based subset of respondents item was asked of. One of “all” (if item was included in the Daily Core and asked of all respondents), “Module A”, or “Module B”.

## Wave 1

Wave 1 was first deployed on April 6, 2020.

Warning: Item A2 shows high missingness and strange values in Wave 1, possibly due to incorrect validation in the Qualtrics survey. Item A2 should not be used in Wave 1 data until this problem is understood.

## Wave 2

Wave 2 was first deployed on April 15, 2020. Some Wave 1 responses were received after this date from respondents who received a link before Wave 2 was deployed.

### Changed Items

• Item A1 changed from

In the past 24 hours, have you or anyone in your household had any of the following:

to

In the past 24 hours, have you or anyone in your household experienced any of the following:

• Item A2 changed to specify “fever, along with at least one other symptom in the above list” rather than simply “at least one symptom.”
• Item A3 changed from

What is the ZIP Code of the city or town where you slept last night? [We mean the place where you are currently staying. This may be different from your usual residence.]

to

What is your current ZIP code?

## Wave 3

Wave 3 was first deployed on May 21, 2020. It is available in English, as well as

• Simplified Chinese
• English (UK)
• Spanish (Latin America)
• Spanish
• French
• Brazilian Portuguese
• Vietnamese

Files:

### Changed Items

• Now available in languages besides English, listed above. The language shown to the user defaults to the language they prefer on Facebook, if available, but a drop-down allows the user to select other languages.
• Consent text now mentions receiving “your language preference” from Facebook, to allow Qualtrics to select the appropriate translation automatically.
• Consent question now requires the respondent be located in the U.S.
• Item B2 now includes eye pain as a symptom.
• Item C5 moved to be asked before item C4.

## Wave 4

Wave 4 was first deployed September 8, 2020. It is available in English and all the languages introduced in Wave 3.

Files:

Wave 4 is a major change to the survey instrument. Some items have been removed and several new items have been added. Please review the changes carefully when you use responses from both waves.

The survey consent text has been altered to more clearly indicate that

Even if you are healthy, your responses may contribute to a better public health understanding of the spread of the coronavirus pandemic and its effects on public health and well-being. This may help improve our local and national responses to the pandemic and our understanding of how it has affected society.

This is broader than the prior text, which suggested the survey was only to understand “where the coronavirus pandemic is moving”, and ensures we obtain consent for the full range of uses for the survey.

### New Items

• Following item B2, item B2c now asks which reported symptoms are “new or unusual” for the respondent. This is intended to distinguish symptoms of chronic conditions (such as allergies) from symptoms that may be COVID-related (or due to influenza or another condition).
• Item B7 now asks whether the respondent has sought medical care, such as visiting a doctor or urgent care clinic. This will allow researchers to understand how people seek medical care, and what fraction of people do so at any given time.
• Items B8, B10, B10a, B10b, B11, B12, and B12a more comprehensively ask about testing, including whether the respondent has tried to be tested but could not get a test, and why they were tested.
• Item C13 asks about specific activities, such as working or going to a restaurant, that the respondent may have done in the past 24 hours. Item C13a asks whether the respondent wore a mask while doing them.
• Item C14 asks “In the past 5 days, how often did you wear a mask when in public?”
• Item D6 now asks if the respondent is of Hispanic, Latino, or Spanish origin. Note that this item is not available in individual response files; see the privacy restrictions information above.
• Item D7 now asks the respondent’s race. Note that this item is not available in individual response files; see the privacy restrictions information above.
• Item D8 asks for the highest level of school the respondent has completed.
• Item D9 asks if the respondent has worked for pay in the past 4 weeks, while items Q64 - Q80 ask the respondent to identify their occupation in a form based on the Standard Occupational Classification System. (Each respondent will only see two of these items; the first requests a broad category, the second a more detailed classification.)
• Item D10 asks if any of the respondent’s work for pay in the past 4 weeks was outside their home.

### Changed Items

• Item B2 now includes eye pain and chills as symptoms.
• Item B2b now asks how long the respondent has had one unusual symptom, if they report having one in item B2c. It no longer asks how long the respondent has had any reported symptom.
• Item C1 now separates type 1 and type 2 diabetes, coded separately. The coding for both is different from the original coding for “diabetes”, so they can be analyzed separately.
• Item C8 now asks how often the respondent has “felt isolated from others”, along with the existing items about anxiety and depression.

### Removed Items

• Item A2b (“How many people are there in your household in total (including yourself)?”) has been removed, as have items D3, D4, and D5. They have been replaced with item A5, which asks for the people in the household broken down by age, including the respondent.
• Items B3 and Q40, asking the temperature of respondents with fevers, have been removed.
• Item B4, asking if the respondent’s cough involved mucus, has been removed.
• Item B5 (“Have you been tested for COVID-19 (coronavirus) for your current illness?”) has been removed. It has been replaced with items B8-B12, described above.
• Item B6 is now subsumed by item B7.
• Item C2 (“Have you had a flu shot in the last 12 months?”) was not being used by research partners and has been removed.
• Item C3 (“In the past 5 days, have you gone to work outside of your home?”) has been replaced by a combination of items C13 and D9.
• Item C4 is replaced by items Q64, Q68, and Q69.
• Item C5 is replaced by items Q64, Q68, and Q69.
• Item C7 (“To what extent are you intentionally avoiding contact with other people?”) is removed, replaced by the more specific items C13, C13a, and C14.
• Item Q36 (“How much of a threat would you say the coronavirus outbreak is to your household’s finances?”) has been removed and replaced with item C15, for consistency with the international version of the survey.
• Item D1b (“Are you currently pregnant?”) has been removed.

## Wave 5

Wave 5 was deployed on November 24, 2020. Deployment was phased: a fraction of users were invited to take Wave 4, while the majority were invited to Wave 5, so data users can determine if changes in responses are due to survey revisions or to population changes at the same time. This overlap lasted roughly seven days. Wave 5 is available in English and all the languages introduced in Wave 3.

Files:

Wave 5 contains minor changes to the survey instrument and a few new items. Please review the changes carefully when you use responses from multiple waves of this survey.

The survey consent text has been altered to encourage respondents to answer the survey, even if they have already taken it before:

We encourage you to complete the survey each time you are invited, even if you have participated before. Completing the survey again will help us understand how the situation is changing.

Wave 5 now clearly states that the data may be shared and aggregates publicly when released:

The de-identified results of this survey may be used for our future studies or shared with other investigators for their research studies. Results published by us and other researchers will be in aggregate and will not identify individual participants or their responses.

### New Items

• Item C16 asks respondents to estimate how many people are wearing masks in their community.
• Item C7 was previously asked in Waves 1-3; it asks respondents the extent they are avoiding other people.
• Item C17 asks whether respondents have received a flu vaccine. The time frame and responses are adapted to specify the current seasonal flu vaccine. A more general version inquiry about the flu vaccine appeared in Wave 1-3 as item C2.
• Items E1-E3 ask about household children and their education during the pandemic. These items appear for respondents who indicate there is a child in their household under the age of 18. E1 asks respondents to indicate the current grade level(s) the child(ren) in their household. Item E2 asks the respondents if the child(ren) are attending in-person classes part time or full time. Item E3 asks respondents what measures are applied to prevent the spread of COVID-19 when the child(ren) attend in-person classes (e.g. mandatory, mask wearing, closed communal areas).
• Note: Soon after survey deployment, we discovered that the translations for French, Brazilian Portuguese, and Spanish (not Latin America) translated these questions to use terms appropriate for education systems in those countries, rather than education in the US. We disabled the question in these translations, and are preparing updated translations that use the correct terms.

### Changed Items

• Item B2 now includes headaches and changes in sleep as symptoms.
• Item D8 now includes the option of Master’s degree (unfortunately omitted in Wave 4) and has examples of professional degree for clarification.

### Removed Items

• There are no items from Wave 4 that were removed in the Wave 5 version of this survey.

## Wave 6

Wave 6 was deployed on December 19, 2020. Deployment was phased: for seven days, a randomly selected portion of respondents continued to receive Wave 5. Wave 6 is available in English and the languages introduced in Wave 3.

Files:

Wave 6 is a minor change to the survey instrument with the addition of a few new items regarding COVID-19 vaccine intent. Please review the changes carefully when you use responses from multiple waves of this survey.

### New Items

• Item V3 asks respondents how likely they would choose to be vaccinated, if they were offered a COVID vaccine.
• Item V4 asks respondents if their intent to get a vaccination would change based on recommendations from different sources (e.g. friends and family, health workers, organizations). Note: Between December 19 and December 23, 2020, non-English translations of this question labeled the answer choices inconsistently with the English version. We corrected this on December 23, and reissued the affected microdata files to delete responses to V4 by respondents seeing an affected translation. The corrected question is labeled V4a in the Qualtrics survey, but appears in the microdata files as V4. Because we reissued the affected data, you should not need to make any changes to your analysis.
• Note: Items V1 and V2 are shown in the Qualtrics files. These ask the respondent if they have received a COVID vaccination. However, due to reidentification concerns, these items were disabled in the display logic, and were not displayed to or asked of respondents. On January 6, 2021, item V1 was enabled, and V3 and V4 were made conditional on respondents not answering “yes” to V1. Item V2 remains disabled in the display logic.

## Wave 7

Wave 7 was deployed on January 12, 2021. Because only minor changes were made in this wave, there was no overlap between waves 6 and 7. It is available in English and the languages introduced in Wave 3.

Files:

Wave 7 includes minor modifications to the existing questions regarding COVID -19 vaccination. Please review the changes carefully when you use responses from multiple waves of this survey.

### Changed Items

• Slight changes to the wording of questions V1, V2, V3, and V4.
• Item V2 was included in Wave 6 but not shown to respondents. We have enabled item V2 for Wave 7.

### New Items

• Item V9 asks if respondents are concerned about a side effect from the COVID-19 vaccination. We ask it of all respondents, regardless of whether they have already received a vaccination.

### Notes

• This wave configures numeric answer items to require answers to be ≥0. We did this via JavaScript by setting the min = "0" attribute on the input box. While this should prevent respondents from accidentally entering negative numbers, those who deliberately want to enter negative numbers can bypass the restriction.

## Wave 8

Wave 8 was deployed on February 8, 2021. It is available in English and the languages introduced in Wave 3.

Files:

Wave 8 expands the scope of the survey items about COVID-19 vaccinations. These new items were meant to capture reasons for vaccine hesitancy among respondents.

### Changed Items

• Answer options for items C1, on chronic medical conditions, have been revised and expanded.
• Answer options for the occupation questions, including Q64, Q68, Q69, and Q71, were revised and expanded for clarity. Please review the changes carefully when you use responses from multiple waves of this survey, since they may shift which occupations respondents choose.
• C14a is a revision of item C14, changed from “the past 5 days” to “the past 7 days” to be consistent with other items on CTIS. C14a replaces C14.
• C17a is a revision of item C17, which asked respondents if they have had a flu vaccination since June 2020. C17a changed the date to July 1, 2020 and simplified the wording.
• In item V4, the “local health workers” category was changed to read “Doctors and other health professionals you go to for medical care”.

### New Items

• Item V2a asks respondents that have received a COVID-19 vaccine and indicated that they have not had 2 doses of the vaccine whether they intend to get the required doses.
• Items V5a-V5d and V6 were added to capture reasons for respondents not wanting to get a COVID-19 vaccine. The questions are displayed based on the respondents’ answers to V2a and V3.
• Item D1b was previously removed in wave 4 and asks respondents that identify as not male if they are currently pregnant.
• Item D11 ask respondents if they smoke cigarettes.

## Wave 9

Wave 9 was skipped to synchronize our numbering with the international survey administered by the University of Maryland.

## Wave 10

Wave 10 was deployed on March 2, 2021. For the following 7 days, roughly 10% of respondents (selected at random) continued to receive Wave 8, allowing for comparisons of responses between the two waves. Wave 10 is available in English and the languages introduced in Wave 3.

Files:

Wave 10 further expands the scope of survey items about COVID-19 vaccination. These new items were meant to capture reasons for vaccine hesistancy among respondents and gauge access. Other items were revised or replaced. Please review the changes carefully when you use responses from multiple waves of this survey.

### New Items

• Item V11 ask respondents if they have an appointment to receive a COVID-19 vaccine.
• Item V12 ask respondents if they have tried to get an appointment to receive a COVID-19 vaccine.
• Item V13 ask respondents how informed they feel about how they will be able to get a COVID-19 vaccine.
• Item V14 asks respondent when they think they will be able to get a COVID-19 vaccine.

### Changed Items

• Item A1 now includes description of fever in Celsius as well as Fahrenheit.
• Item A5 was changed to say “from 18 to 64 years old” instead of “between 18 and 64 years old”.
• The instructions following the question text in items B2 and D7 was changed to be consistent with all other multiple response questions and reads “Please select all that apply.”
• Item B10a was changed to remind the respondent “You answered that you have been tested for coronavirus (COVID-19) in the past 14 days.”
• Items B10b, C13a, C13b, was changed to now state “in the past 14 days”, versus the previous version that stated “in last 14 days”.
• Item B10b response options were changed to provide more specificity. Blood donation was added to the option “I was tested while receiving other medical care, such as surgery” and a “None of the above” response option was added to be consistent with other questions.
• Item V2a was changed to say “recommended doses”; previous versions said “required doses” (V2).
• Items V5a-V5d question wording was changed to better match the question stem (V3). For example, if respondents selected for Item V3 (“If a vaccine to prevent COVID-19 were offered to you today, would you choose to get vaccinated?”) response option 2 (“Yes, probably”). The following question would be V5a (“Which of the following, is any, are reasons that you only probably would choose to get the COVID-19 vaccine?”).
• Item V9 was made conditional on respondents not answering “yes” to V1.
• Item C13 was replaced with item C13b, which asks specifically whether the activities occurred indoors. Item C13a was similarly replaced with item C13c to reflect mask use during those indoor activities.
• Items C6 and C8 were changed to refer to the past 7 days, rather than the past 5 days, to be consistent with other items on the survey. They were renamed to C6a and C8a to reflect this change.
• Typos were fixed in Q67 and Q78.

### Removed Items

• Item B2b (“For how many days have you had at least one new or unusual symptom?”) was removed.
• Item C11 (“In the past 24 hours, have you had direct contact with anyone who recently tested positive for COVID-19 (coronavirus)?”), and the follow-up question, item C12 (“Was this person a member of your household?”), were removed.
• Item A3b (“In which state are you currently staying?”) was removed. Respondents are asked their ZIP code in item A3, and while some ZIP codes cross state lines, we judged the duplication was not necessary.

## Wave 11

Wave 11 was deployed on May 20, 2021. For the following 30 days, about 10% of respondents (selected at random) continued to receive Wave 10, allowing for comparisons of responses between the two waves. It is available in English and the languages introduced in Wave 3.

Files:

Wave 11 is a major revision of the survey instrument. There are several new items expanding the scope of COVID-19 vaccines, beliefs, knowledge, and norms; major revisions to some of the existing items; and several minor revisions that consists of grammar and style changes for consistency. Please review the changes carefully when you use responses from multiple waves of this survey.

In this wave, we introduced a module structure to the survey. All respondents see “daily core” items, and are then randomly selected to receive either questions in Module A or Module B. Half of respondents will see each module. See the survey modules and randomization documentation for details.

### New Items

#### Daily Core

• Item B2b was previously removed in Wave 8 and has been reinstated. It asks respondents how many days they have had new and unusual symptoms.
• Item B13 asks respondents “As far as you know, have you ever had coronavirus (COVID-19)?”
• Items V15a and V15b ask respondents the barriers they experience to getting the COVID-19 vaccine.
• Item V16 asks respondents when they will try to get a COVID-19 vaccine.
• Item D12 asks respondents what language they most often speak at home.

#### Module A

Module A includes items on beliefs, norms, and knowledge & information.

Belief items:

• Item G1 asks respondents how much they worry about catching COVID-19.
• Item G2 asks respondents how effective social distancing is for preventing the spread of COVID-19.
• Item G3 asks respondents how effective wearing a face mask is for preventing the spread of COVID-19.

Norms items:

• Item H1 asks respondents when they were in public in the past 7 days, how many people maintained at least 6 feet from others. Note: The French translation of this item was initially incorrect. See the error log for details on the fix.
• Item H2 asks respondents when they were in public in the past 7 days, how many people wore face masks.
• Item H3 asks respondents thinking about their friends and family, how many have gotten a COVID-19 vaccine.

Knowledge & information items:

• Item I1 asks respondents whether they think the statement “Getting the COVID-19 vaccine means that you can stop wearing a mask around people outside your household” is true or false.
• Item I2 asks respondents whether they think the statement “Children cannot get COVID-19” is true or false.
• Item I3 asks respondents whether they think the statement “COVID-19 was deliberately created by a small group of people who secretly manipulate world events” is true or false.
• Item I4 asks respondents whether they think the statement “COVID-19 pandemic is being exploited” is true or false.
• Item I5 asks respondents in the past 7 days, from which sources did they receive news and information about COVID-19.
• Item I6 asks respondents to indicate how much they trust the sources to provide them with accurate news and information about COVID-19.

#### Module B

Module B includes well-being, healthcare, and parenting items.

Well-being:

• Item C18a and C18b are major revisions of a previous item C8a. To improve user experience on mobile devices, the matrix format was taken out and the first two sub-questions were reformatted into individual Likert scale questions.
• Item C18a asks respondents in the past 7 days, how often they felt nervous, anxious or on edge.
• Item C18b asks respondents in the past 7 days, how often they have felt depressed.

Healthcare:

• Item K1 asks respondents in the past year if they have delayed or not sought medical care because of cost.
• Item K2 asks respondents how much they agree or disagree with the statement, “People of my race are treated fairly in a healthcare setting.”

Parenting:

• Item E4 ask respondents, “Will you choose to get a COVID-19 vaccine for your child or children when they are eligible?”

Note: On July 11, 2021, questions E2 and E3 in Wave 11 were inactivated for the summer. Revised versions of schooling questions are planned for launch in Wave 12.

### Changed Items

Major revisions include significant wording changes, display logic changes, and changes to which respondents are asked the items, or any changes that are anticipated to change the respondent’s answer to the question. For user ease, the variable name will be changed (e.g. X1→X1a) if a major revision occurs, to distinguish the version of the variable from the previous wave and the revised variable in the current wave.

• Item B10c asks respondents “Did your most recent test find that you have COVID-19?” and replaces item B10a “You answered that you have been tested for coronavirus (COVID-19) in the past 14 days. Did this test find that you have coronavirus (COVID-19)?” from the previous wave.
• Item V11a “Do you have an appointment to receive a COVID-19 vaccine?” is now asked of all respondents that did not select “yes” to item V1 “Have you had a COVID-19 vaccination?”
• In the previous wave, item V11 “Do you have an appointment to receive a COVID-19 vaccine?” was asked of respondents who reported “Yes, definitely” or “Yes, probably” to item V3 “If a vaccine to prevent COVID-19 were offered to you today, would you choose to get vaccinated?”
• Item V3a “If a vaccine to prevent COVID-19 were offered to you today, would you choose to get vaccinated?” is now asked of all respondents that did not select “yes” to item V1 “Have you had a COVID-19 vaccination?” and did not select “yes” to item V11a “Do you have an appointment to receive a COVID-19 vaccine?”
• In the previous wave, item V3 “If a vaccine to prevent COVID-19 were offered to you today, would you choose to get vaccinated?” was asked of all respondents that did not select “yes” to item V1 “Have you had a COVID-19 vaccination?”
• Item V12a asks respondents “Have you tried to a get a COVID-19 vaccine?” and replaces item V12 “Have you tried to get an appointment to receive a COVID-19 vaccine?” from the previous wave. This item is asked of respondents who did not select “yes” to item V1 “Have you had a COVID-19 vaccination?” and did not select “yes” to item V11a “Do you have an appointment to receive a COVID-19 vaccine?” and did not select “No, definitely not” to item V3a “If a vaccine to prevent COVID-19 were offered to you today, would you choose to get vaccinated?”
• In the previous wave, item V12 “Have you tried to get an appointment to receive a COVID-19 vaccine?” was asked of respondents who reported “Yes, definitely” or “Yes, probably” to item V3 “If a vaccine to prevent COVID-19 were offered to you today, would you choose to get vaccinated?” and those respondents that did not select “yes” to item V11a “Do you have an appointment to receive a COVID-19 vaccine?”
• Item C7a ask respondent “In the past 7 days, how often did you intentionally avoid contact with other people?” and replaces item C7 “To what extent are you intentionally avoiding contact with other people?” from the previous wave. In version, this item also has a different response scale.

Minor revisions include changes made to formatting, grammar, addition and/or removal of response options. These changes have been classified as minor as they are not anticipated to change the respondent’s answer.

• Slight format (i.e. removing bolding) and wording changes (i.e. coronavirus was changed to COVID-19) occurred for items: A2, A4, B10, B10b, B12, B12a, V5a-c, V6, C6, D10, and Q64 – Q80 (occupation questions).
• Items B2 and B2c response options: “nasal congestion”, “runny nose”, “eye pain”, and “changes in sleep” were removed. The response option “stuffy or runny nose” was added and coded to be a new, distinct response option.
• Item B10b response options: “I attended a large outdoor event or gathering” and “I was in a crowded indoor environment” were removed. The response option “It was required for domestic or international travel” was added.
• Item B12a response option, “I am worried about bad things happening to me or my family (including discrimination, government policies, or social stigma)” was removed. The response option “I am worried about being exposed to COVID-19 at the testing location” was added.
• For items V5a-c, response options: “I am concerned about having an allergic reaction to a COVID-19 vaccine”, “My doctor has not recommended it”, “I don’t trust COVID-19 vaccines”, “I have a health condition and am concerned about the safety of the vaccine for people with my condition”, and “I am currently/planning to be pregnant and/or breastfeeding and do not want to get vaccinated at this time” were removed.
• Item C13c response option “none of the above” was added to allow respondents who engaged in activities (C13b) to report if they did not wear a mask during any of those activities.
• Item C1 response option “auto immune disorder such as rheumatoid arthritis or Crohn’s disease” was removed.

### Removed Items

• Item B7 (“Have you sought medical care for your recent unusual symptoms?”) has been removed.
• Item B8 (“Have you ever been tested for coronavirus (COVID-19)?”) has been removed.
• Item B11 (“Have you ever tested positive for coronavirus (COVID-19)?” has been removed.
• Item B12 (“Have you wanted to be tested for coronavirus (COVID-19) at any time in the last 14 days?”) has been removed.
• Item B12a (“Do any of the following reasons describe why you haven’t been tested for coronavirus (COVID-19) in the last 14 days?”) has been removed.
• Item V2a (“Did you receive (or do you plan to receive) all required doses?”) has been removed.
• Item V5d (“Which of the following, is any, are reasons that you don’t plan to receive all recommended doses of a COVID-19 vaccine?”) has been removed.
• Item V13 (“How informed do you feel about how you will be able to get a COVID-19 vaccine?”) was removed.
• Item V14 (“When do you think you will be able to get a COVID-19 vaccine?”) was removed.
• Item V4a (“Would you be more or less likely to get a COVID-19 vaccination if it were recommended to you by each of the following: ”) was removed.
• Item C8a, subitem 3 (“In the past 7 days, how often have you felt isolated from others?”) was removed. Subitems 1 and 2 were reformatted to individual Likert scale questions, see items C18a and C18b under new items.
• Item C10 (“In the past 24 hours, with how many people have you had direct contact, outside of your household?”) was removed.
• Item C9 (“How worried do you feel that you or someone in your immediate family might become seriously ill from CVOID-19?”) was removed.
• Item C17a (“Have you had a seasonal flu vaccination since July 1, 2020?”) was removed.
• On November 8, 2021, item V2 “How many vaccinations have you received?” was removed from Wave 11, as the response options did not allow for respondents to report booster shots and additional doses. Booster doses were becoming more common at this time, making the lack of booster response options jarring to respondents.

### Notes

• The following survey items were rearranged for better survey flow and/or allocated to specific modules:
• Daily core: A3, V11a, C6a, C14a, and D8
• Module B: C15, C1, D11, and D1b
• For survey items with response options in Likert scales or multiple answers, random scale reversal and randomization of response options will be set where applicable. Randomization of response options was added to B10b starting with Wave 11.

## Wave 12

Wave 12 was deployed on December 19, 2021, after an experimental phase in October:

• From October 7 to October 22, 2021, an experimental Wave 12 was given only to 15% of survey respondents, the remainder receiving Wave 11. This phase was used to conduct three experiments with (1) demographic module placement, (2) vaccination uptake question, and (3) survey invitation text. Details of these experiments can be found below. In data files, this is marked as wave “12.5” to distinguish from the final version. Data from the experimental wave 12 was not included in the aggregates published in the COVIDcast API or in our contingency tables.
• After results of the experiments were analyzed, the final version was deployed on December 19, 2021. In data files, this is marked as wave 12.

Wave 12 is available in English and the languages introduced in Wave 3.

Files:

• Experimental wave 12:
• Final version of Wave 12:

Besides the experiments, Wave 12 revised the schooling module of the survey instrument and adds questions regarding parents’ intention to vaccinate their children (under age 18). These schooling items are part of Module B of the survey. Please review the changes carefully when you use responses from multiple waves of this survey.

### Demographic Module Placement

In the prior waves of CTIS, respondent demographics were collected towards the end of the survey. These questions are now asked after the vaccine module of the survey. This placement was chosen after the order experiments described below found that this ordering improved response rates to the demographic items. We expect this will aid users who need demographic data for their survey analyses.

### New Items

• Item P1 asks if the respondent is a parent or legal guardian of a child under age 18.
• Item P2 asks respondents the age group of their oldest child. This replaces item E1.
• Item P3 asks the respondent if they will choose to have their oldest child vaccinated when the child is eligible to be vaccinated. This replaces item E4.
• Item P4 asks the respondent about the type of schooling their oldest child is enrolled in, such as public or private schooling.
• Item P5 asks the respondent to describe their current schooling for their oldest child: in-person, online/remote, or a mixture.
• Item P6 asks respondent about the preventative measures that apply if their oldest child is attending any in-person classes. These response options are a subset of response options from E3 with several new additions.
• In the experimental phase, item V1alt asked respondents who they personally know has already received a COVID-19 vaccine. Response options include themselves, household members, and others. This is an alternate form of item V1 capturing vaccine uptake, and is part of the vaccination uptake question experiment described below. In the final version of Wave 12, item V1alt is not used and item V1 remains unchanged.

### Changed Items

• Item B13a asks respondents “Have you ever had coronavirus (COVID-19)?” and replaces item B13 “As far as you know, have you ever had coronavirus (COVID-19)?” for ease of translation.
• Item V5a, V5b and V5c have the following revisions to response options:
• The response option “I don’t like vaccines” was revised to “I don’t like vaccines generally” to distinguish from a specific dislike of COVID-19 vaccines.
• The response option “I don’t trust COVID-19 vaccines” is a response option from Wave 8 that was added back in Wave 12.
• Item V15a was replaced with V15c, which asks respondents “Did you ever experience any of the following barriers to getting the COVID-19 vaccine?” The word ever was added to clarify for those who have received the vaccine but may have experienced barriers prior to being vaccinated. Additionally, two response options were added: “The available appointment locations did not work for me” and “Other”
• Item V15b has two new response options: “The available appointment locations did not work for me” and “Other”.
• The vaccination uptake question experiment, part of the experimental version of Wave 12, used questions V1 and V1alt. During the experiment, questions that use V1 in the display logic were updated to also include respondents who are asked V1alt. The display logic was updated for the following questions: V2, V11a, V3a, V5a, V12a, V16, and V9.

### Removed Items

• Item E4 “Will you choose to get a COVID-19 vaccine for your child or children when they are eligible?” was removed.
• Item E1 “Are there any children in your household in any of the following grades?” was removed.
• Item E2 “Do any of the following apply to any children in your household (pre-K – grade 12)?” was removed.
• Item E3 “Do any of the following measures apply to the children in your household when they attend in-person classes (pre-K-grade 12)? was removed.

### Experiments

Wave 12 was initially launched to 15% of respondents to collect data for the experiments described below. (The remaining 85% continued to receive Wave 11.) This experiment was run from October 7 to October 22, 2021. After the experiments were conducted and the data analyzed, the CTIS team finalized the Wave 12 instrument to be distributed to the entire sample. This finalized version was deployed on December 19, 2021.

The Wave 12 trial phase consisted of three experiments with (1) demographic module placement, (2) vaccination uptake question, and (3) survey invitation text.

#### Demographic Module Placement and Vaccine Uptake Question

The 15% of respondents who received the experimental Wave 12 were divided into three groups:

• Group 1 (5% of respondents) saw the demographics questions after the symptom module, which concludes with question B2b “For how many days have you had at least one new or unusual symptom?” This group of respondents saw the Wave 11 version of the vaccine uptake question (V1).
• Group 2 (5% of respondents) saw the demographics questions after the COVID vaccine module, which concludes with question V9 “How concerned are you that you would experience a side effect from a COVID-19 vaccination?” This group of respondents saw the Wave 11 version of the vaccine uptake question (V1).
• Group 3 (5% of respondents) saw the experimental form of the vaccination uptake question (V1alt), which asks respondents “Do you personally know anyone who has received the COVID-19 vaccine already?” Response options include themselves, household members, and others. These respondents did not receive the previous vaccine uptake question, V1. They saw the demographic questions in the Wave 11 placement, at the end of Module A/B and before the occupation questions.

A new column w12_treatment in the microdata files indicates which of the three groups above each respondent was assigned to.

#### Survey Invitation Text

During the Wave 12 experiment period, our partners at Facebook conducted an experiment among those respondents allocated to receive Wave 11. Among those participants, 6% received one of six different invitations to the survey on their News Feed. This was an internal Facebook experiment conducted with the goal of improving response rates and exploring additional non-response bias in the weighting process. More details will be provided when the survey invitation is finalized.

## Wave 13

Wave 13 was deployed on January 30, 2022. For the following two weeks, about 15% of respondents (selected at random) received Wave 12 and the remainder received Wave 13, allowing for comparisons of responses between the two waves. Wave 13 is available in English and the languages introduced in Wave 3.

There are two objectives of this revision. First, we modified the COVID-19 vaccination questions to collect information about additional doses and booster shots. We also removed questions that are not being used to reduce response burden.

Files:

### New Items

• Introductory text was added for respondents that responded “yes” to item V2, “Have you had a COVID-19 vaccination?”. This text explains initial, booster, and additional doses of the COVID-19 vaccination. The following three questions collect information regarding the COVID-19 vaccinations the respondent received. The introductory text reads:

Initial doses of the COVID-19 vaccination are a one or two shot sequence, depending on the brand of vaccine.

Booster shots or additional doses are doses received following that initial sequence.

To interpret data from these questions, we recommend reviewing the CDC’s guidelines on vaccination for immunocompromised people. As of January 2022, immunocompromised people can receive up to four doses: two primary doses (for Pfizer and Moderna vaccines), an additional primary dose 28 days later, and a booster dose 5 months afterward. However, awareness of this is uneven, which is why item V2b (below) does not distinguish between booster and additional doses.

• Item V2d asks respondents about the doses of the COVID-19 vaccination they received in their initial sequence. This is a revision from previous item V2 and the response options distinguish between one dose vaccines, two dose vaccines, and incomplete 2 dose vaccine sequences.
• Item V2b asks respondents if they have received an additional dose or booster shot of the COVID-19 vaccination.
• Item V2c asks respondents that have not yet received an additional dose or booster shot whether they plan to get one.
• Item C17b asks respondents if they received a flu vaccination since July 2021. This is an updated version of item C17a (waves 8-10) and C17 (waves 5-7), which descended from item C2 (waves 1-3).
• Item V17 asks respondents when they received their most recent COVID-19 vaccination. Due to programming issues, the launch of this question was delayed. The question was deployed on February 27, 2022.

### Changed Items

• Item D1 was changed in the Spanish translation to ask “¿Con qué género te identificas?” to keep consistency between survey instruments, and to match the Spanish (Latin America) translation. (The Spanish translation previously read “¿De qué sexo eres?”)

### Removed Items

• Item B10b (“Do any of the following reasons describe why you were tested for COVID-19 in the past 14 days?”) has been removed.
• Item V2 (“How many COVID-19 vaccinations have you received?”) has been removed.
• Item V15c (“Did you ever experience any of the following barriers to getting the COVID-19 vaccine?”) has been removed
• Item C6a (“In the past 7 days, have you traveled outside of your state?”) has been removed.
• Item I1 (“Getting the COVID-19 vaccine means that you can stop wearing a mask around people outside your household.”) has been removed.
• Item I2 (“Children cannot get COVID-19.”) has been removed.