Date: April 2023
Program manager: Director, Center for Direct Health Measures
Director General, Health Statistics
Original Supplement to the Canadian COVID-19 Antibody and Health Survey (CCAHS) - Privacy impact assessment summary:
Supplement to Privacy Impact Assessment for the Canadian COVID-19 Antibody and Health Survey for Cycle 2
Reference to Personal Information Bank (PIB):
Personal information collected through the voluntary Canadian COVID-19 Antibody and Health Survey – Follow-up Questionnaire, 2023 is described in Statistics Canada's "Health Surveys" PIB, (Bank number: StatCan PPU 806) which is published on the Statistics Canada website for Information about Programs and Information Holdings.
Description of changes to the statistical activity:
Statistics Canada conducted the voluntary Canadian COVID-19 Antibody and Health Survey (CCAHS) Cycle 2 from April to August 2022, a survey for which a Supplement to the Privacy Impact Assessment for the Canadian COVID-19 Antibody and Health Survey for Cycle 2 was created.
For this voluntary follow-up survey, 80% of respondents (26,036 individuals) from the second cycle of the Canadian COVID-19 Antibody and Health Survey (the parent survey) who voluntarily provided a valid email address at the end of the survey for follow-up by Statistics Canada will be contacted and asked to participate in the online questionnaire.
The content of the Canadian COVID-19 Antibody and Health Survey – Follow-up Questionnaire, 2023 (follow-up) is a mix of new and reused CCAHS Cycle 2 questions. As with the parent survey, the follow-up will collect a variety of personal information such as: the presence of chronic conditions and symptoms, COVID-19 status, vaccination against COVID-19, prescription medication use to treat COVID-19, impacts to work or school and interactions with the health care system from experiencing COVID-19 and sources of income and labour market activities.
Key differences between the parent survey and the follow-up include:
- The follow-up will be collected longitudinally: the sample for the follow-up will be limited to CCAHS Cycle 2 participants who provided a valid email address after being informed that Statistics Canada could contact them in the future to follow-up on some of the information they provided in the survey. Microdata linkage will be performed to link individual respondent information between the parent survey and the follow-up.
- The follow-up will not repeat the parent survey biospecimen (blood sample) collection or the survey content related to testing, e.g., consent to test and biobank samples.
- The follow-up will not repeat the parent survey collection of the following modules from the CCAHS Cycle 2 questionnaire: contact information, demographics, pregnancy status, general health and risk factors.
- The follow-up will introduce new questions to determine the recency of COVID-19 infections, severity of symptoms, support for symptom management, and respondents’ reliance on disability benefits or worker’s compensation.
Reason for addendum:
While the Supplement to the Privacy Impact Assessment for the Canadian COVID-19 Antibody and Health Survey for Cycle 2 addresses most of the privacy and security risks related to statistical activities conducted by Statistics Canada, this addendum describes the changes related to the Canadian COVID-19 Antibody and Health Survey – Follow-up Questionnaire, 2023 and demonstrates the necessity and proportionality of removing the biospecimen collection component, making the follow-up longitudinal and collecting additional sensitive information not addressed in either of the previous CCAHS PIAs on receiving disability benefits or worker’s compensation.
Necessity and Proportionality
The collection of personal information for the program can be justified against Statistics Canada’s Necessity and Proportionality Framework:
1. Necessity
1.1 Removal of biospecimen collection
The collection of additional biospecimens is no longer a data requirement as the focus of the research program has shifted from determining SARS-CoV-2 seroprevalence and active infection status to gathering updated self-reported health information from respondents.
1.2 Longitudinal nature of collection
The need for a longitudinal questionnaire linking respondent information from the parent and follow-up surveys emerged based on the changing impacts of the pandemic and increasing knowledge about the post-COVID-19 condition (PCC) and its relatively high prevalence in those who had COVID-19. Comparing data over time will allow for a more accurate analysis of the outcomes of SARS-CoV-2 infection by extending the follow-up time to track the evolution of symptoms, including the persistence of PCC, while considering the mediating effects of reinfections. The longitudinal aspect of the survey aims to fulfill the data gaps surrounding the longer-term health, financial and social impacts of COVID-19.
1.3 New disability benefits or workers’ compensation question
New data is required to investigate if experiencing a SARS-CoV-2 infection and/or its resulting health outcomes is associated with obtaining disability benefits and workers’ compensation, in an aim to increase the availability of high-quality evidence to support the mandate of public health authorities in Canada. These data could, for instance, help to better understand the impacts of PCC on Canadians, including possible financial effects related to the type and longevity of symptoms. The data will also enable an evaluation of existing disability and workers’ compensation services during the pandemic recovery.
2. Effectiveness - Working assumptions:
2.1 Removal of biospecimen collection
Biospecimen collection does not fall within the scope of the follow-up; prevalence for antibody and active COVID-19 infections are not required and therefore not collected for this questionnaire.
2.2 Longitudinal nature of collection
Data from the follow-up will be combined with CCAHS Cycle 2 data to produce the evidence needed to inform decision-making. A longitudinal survey design is selected over repeating a cross-sectional survey design because it enables the use of a shorter collection instrument to track the potential persistence of health outcomes (e.g., long-term symptoms) following a SARS-CoV-2 infection while reducing the burden on respondents. Moreover, the relatively invasive biospecimen collection of self-administered dried blood spot tests does not need to be repeated in this longitudinal cohort of Canadians, as they have already self-administered and returned biospecimens that confirmed the status of a prior infection through antibody testing. No additional follow-ups are planned for the selected cohort of participants.
2.3 New disability benefits or workers’ compensation question
The new question and wording for disability benefits and worker’s compensation is based on a question from Statistics Canada’s 2022 Canadian Survey on Disability that was tested and performed well in the field. A minor adjustment was made to the question to include a reference to benefits from the workers’ compensation program as the target population of the follow-up is not limited to Canadians who previously reported living with a disability.
3. Proportionality
3.1 Removal of biospecimen collection
Proportional to evolving needs, the removal of biospecimen collection reduces both respondent burden and the privacy invasiveness associated with the collection of sensitive data.
3.2 Longitudinal nature of collection
Those who responded to the parent survey detailed their experience surrounding a first COVID-19 experience in the context of SARS-CoV-2 variants circulating between the start of the pandemic and the end of August 2022; as the virus is continually evolving, a longitudinal survey design enables Statistics Canada to complement existing respondent information and investigate the impacts of reinfections, evolving variants and whether persisting post-infection symptoms have resolved. Furthermore, by linking follow-up data to parent survey data and not readministering the baseline health and sociodemographic questions that are necessary for analyses of quality, the follow-up survey allows for a proportional reduction in respondent burden leading to improved response rates in a population that is being surveyed twice in less than a year. Surveying all eligible respondents for the follow-up, as opposed to a sub-sample, was deemed methodologically necessary to reach or exceed the minimum number of respondents required to produce and publish disaggregated statistics by sub-population and province while protecting the privacy of the individual respondents. While the questionnaire collects sensitive health data, careful consideration was made to avoid adversely impacting the privacy of respondents by limiting the number of questions being asked. Compared to its parent survey, which had 72 questions, the follow-up is limited to 26 questions. This step limits the overall survey completion time and invasiveness of the research program. Moreover, the longitudinal nature of the follow-up questionnaire removes the need to request that a new cohort of respondents self-administer the relatively invasive biospecimen test.
3.3 New disability benefits or workers’ compensation question
Fulfilling this data gap could help identify health inequities and better evaluate existing programs and services to better inform the pandemic recovery efforts. This is particularly relevant given the high prevalence (≈15%) of Canadians who were previously infected by SARS-CoV-2 who may be affected by PCC.
4. Alternatives
4.1 Removal of biospecimen collection
No alternatives considered as this action reduces privacy invasiveness and the burden of self-administered tests on respondents.
4.2 Longitudinal nature of collection
There are no other sources of nationally representative data on the longitudinal progression of COVID-19 symptoms and reinfections in Canada, at the person level, in individuals for whom we have sociodemographic information, health status data such as existing chronic conditions and symptoms, and COVID-19-specific health data such as vaccination and infection status confirmed through antibody testing, dating back to the start of the pandemic.
4.3 New disability benefits or workers’ compensation question
There are no other data sources collecting or combining information on disability benefits or workers’ compensation with individual level confirmation of SARS-CoV-2 seropositivity (a positive result of a blood test for SARS-CoV-2 antibodies), chronic conditions and symptoms, progression and symptoms of PCC, details about a prior infection, vaccination status, pre-existing conditions, the use of and challenges with accessing health care services along with sociodemographic information that will enable the disaggregated statistics by sub-population and province.
Mitigation factors
The overall risk of harm to the survey respondents has been deemed manageable with the implementation of existing Statistics Canada safeguards that are described in Statistics Canada’s Generic Privacy Impact Assessment, the Canadian COVID-19 Antibody and Health Survey (CCAHS) - Privacy Impact Assessment, and the Supplement to Privacy Impact Assessment for the Canadian COVID-19 Antibody and Health Survey for Cycle 2, including the following:
- The longitudinal collection and microdata linkage between the parent survey and the follow-up survey will result in the latter collecting less sensitive content overall.
- Removal of the self-administered blood sample will similarly reduce privacy invasiveness by eliminating biospecimen collection from the follow-up.
- Respondents were duly informed that participation in the parent survey was voluntary, that their information could be combined with other data, and that their contact information could be used to contact them for follow-up:
Voluntary participation
The Canadian COVID-19 Antibody and Health Survey (CCAHS) aims to collect important information about lasting general health problems and symptoms and about post-COVID-19 condition. The purpose is to gather information on the presence of COVID-19 among the Canadian population, protection against COVID-19, health concerns, use of the health care system and prescribed medications. This information will be collected in two parts: through an electronic questionnaire and through a self-administered COVID-19 testing component.
Even if you do not think you have been exposed to COVID-19, your participation is important as it will provide useful information about the virus and insight into the overall health of Canadians. You will also receive a copy of your lab report, providing you with valuable information about your own health. Survey results will be used to develop programs and services to respond to needs related to the pandemic.
Your information may also be used by Statistics Canada for other statistical and research purposes.
Although voluntary, your participation is important so that the information collected is as accurate and complete as possible.
Record linkages
To enhance the data from this survey and to minimize the reporting burden for respondents, Statistics Canada will combine your responses with information from the tax data of all members of your household. Statistics Canada and the ministry of health for your home province or territory may also add information from other surveys or administrative sources.
For Quebec residents, the Institut de la statistique du Québec may add information from other surveys or administrative sources.
Having a provincial or territorial health number will assist Statistics Canada in linking the survey data to the provincial or territorial health information.
Contact information
Statistics Canada may contact you in the future to follow-up on some of the information you have provided. …
Wording in the survey purpose and data linkage content at the beginning of the follow-up questionnaire informs respondents of the longitudinal nature of the survey:
Why are we conducting this survey?
Understanding how the COVID-19 pandemic has affected the health and well-being of Canadians is an important step toward Canada’s recovery. To support this goal, Statistics Canada and the Public Health Agency of Canada have partnered to conduct a follow-up to the Canadian COVID-19 Antibody and Health Survey (CCAHS – Follow-up Questionnaire). The data from this survey will be combined with data from cycle 2 of the CCAHS, which was conducted between April and August 2022, to produce the evidence needed for informed decision-making.
This follow-up will collect updated information about your health. The questions will touch on changes in vaccination status, reinfection with the virus that causes COVID-19, symptoms of COVID-19 and impact on daily life, health conditions and the use of health care services.
Your information may also be used by Statistics Canada for other statistical and research purposes.
Although voluntary, your participation is important so that the information collected is as accurate and complete as possible.
Record linkages
To enhance the data from this survey and to reduce the response burden, Statistics Canada will combine the information you provide with information from the Canadian COVID-19 Antibody and Health Survey (CCAHS) – Cycle 2.
Statistics Canada may also combine the information you provide with other survey or administrative data sources.
Wording in the data sharing content in the follow-up questionnaire informs respondents of the data sharing agreements:
Data sharing agreements
To avoid duplication of surveys, Statistics Canada may enter into agreements to share the data from this survey with provincial and territorial ministries of health, Health Canada and the Public Health Agency of Canada. For Quebec residents, Statistics Canada may also enter into an agreement with the Institut de la statistique du Québec to share the same information.
The Institut de la statistique du Québec and provincial ministries of health may make this data available to local health authorities. Local health authorities will not receive any identifiers.
These organizations have agreed to keep the data confidential and use it only for statistical purposes.”
Conclusion:
This assessment concludes that with the existing Statistics Canada safeguards and mitigations listed above, any remaining risks are such that Statistics Canada is prepared to accept and manage the risk.