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COVID-19 Trends and Impact Survey FAQ: End of Data Collection


Why is CTIS data collection concluding?

CTIS was built at the height of the global COVID-19 emergency in April 2020 to enable daily syndromic surveillance at a time when testing and data on the emerging pandemic were limited. Since CTIS launched, pandemic response decision-makers from around the world have utilized CTIS’ daily data on symptoms associated with COVID-19, such as fevers, coughing or shortness of breath – as well as other topics covered in the survey from mask wearing to COVID-related job loss. See the next section to learn more about how CTIS has supported the COVID-19 response.

At this point in the pandemic, reliable data tracking similar topics as CTIS have become more widely available. Additionally, CTIS response rates have declined over time, and as COVID-19 has evolved, there is less need for large, daily data collection and greater need for measurement of topics that do not change significantly on a daily basis. Since CTIS is designed specifically for large-scale, daily data collection, the Delphi Group at Carnegie Mellon University (CMU), the University of Maryland Social Data Science Center (UMD) and Meta have made the decision to stop collecting new survey responses. We are working to curate and archive the tens of millions of privacy-protected survey responses received since 2020 and the aggregate estimates derived from them to ensure the data remain available to academic and nonprofit researchers.

The conclusion of new data collection will occur in two phases: Sampling will be suspended in 74 countries on April 15, 2022, including 24 unweighted countries and 50 weighted countries where sampling sizes are insufficient for analyses of weekly or monthly trends (countries listed below). Sampling will be suspended in the rest of the 64 countries, including the United States, on June 25, 2022.

Why will data collection for some countries stop on April 15, 2022?

Of the 74 countries where daily data collection will be suspended on April 15, 2022, 24 are countries with unweighted data and 50 are countries with weighted data where sample sizes are not large enough to statistically power the detection of weekly or monthly trends in signals. Data collection for these countries has continued in large part because specific technical partners have been utilizing these data to power advanced statistical models predicting when and where the next wave of COVID-19 cases would occur. At this stage of the pandemic, there is a greater need for weekly and monthly trends of behavioral measures to inform different kinds of public health decisions.

What countries are included in the data collection ramp down on April 15, 2022?

On April 15, 2022, data collection will stop in 74 countries and territories. This includes 24 countries with unweighted data and 50 countries with weighted data:

  • Unweighted countries: American Samoa; Andorra; Bahamas (the); Bahrain; Belize; Bermuda; Botswana; Congo (the); Cyprus; Dominica; Estonia; Gabon; Georgia; Iceland; Latvia; Lithuania; Luxembourg; Malta; Montenegro; South Sudan; Timor-Leste; Uganda; Zambia; Zimbabwe
  • Weighted countries: Albania; Angola; Armenia; Azerbaijan; Benin; Bosnia and Herzegovina; Burkina Faso; Cambodia; Cameroon; Congo (the Democratic Republic of the); Costa Rica; Denmark; Dominican Republic (the); Ecuador; El Salvador; Finland; Guinea; Haiti; Hong Kong; Ireland; Israel; Kazakhstan; Kuwait; Kyrgyzstan; Lao Peoples Democratic Republic (the); Madagascar; Malaysia; Mali; Mauritania; Moldova (the Republic of); Morocco; Nicaragua; Norway; Oman; Palestine, State of; Panama; Puerto Rico; Qatar; Saudi Arabia; Senegal; Singapore; Sri Lanka; Sudan (the); Tanzania, the United Republic of; Tunisia; Turkey; United Arab Emirates (the); Uzbekistan; Venezuela (Bolivarian Republic of); Yemen


What impact has CTIS had in the past two years?

CTIS is the largest public health survey ever conducted and has been used to inform the decisions of governments, health organizations, nonprofits, research institutions and academics around the world as they implemented their COVID-19 response efforts. The survey data has been used by over 100 stakeholders across over 60 countries. CTIS has demonstrated the positive impact that surveys of health behaviors and needs can have on improving access to health information, support and care.

For example, the Institute of Health Metrics and Evaluation (IHME) uses CTIS data to inform its COVID-19 prediction models. Via these models, CTIS mask wearing data informed a mask mandate in Poland, which contributed to a significant drop in COVID-19 cases. In the US, a Johns Hopkins University study using CTIS data published in Science on household COVID-19 risk and in-person schooling contributed to the US CDC’s Independent Advisory Committee on Immunization Practices’ recommendation to allow vaccinations in younger children. A study published in Proceedings of the National Academy of Sciences (PNAS) by researchers at Boston’s Children’s Hospital used data from the Global CTIS to identify known symptom predictors of testing positive for COVID-19, highlighting the role of CTIS data for supporting existing surveillance systems for COVID-19 as well as other potential global health threats.

In the Philippines, the USAID Breakthrough ACTION Project is using the Johns Hopkins Center for Communications Programs (JH CCP) COVID Behaviors Dashboard that visualizes CTIS data to support COVID-19 prevention and vaccine confidence campaigns in partnership with the Philippines Department of Health. The dashboard allowed Breakthrough ACTION to uncover local healthcare workers as a trusted source of information, leveraging them as a channel for countering vaccine hesitancy and misinformation. We are grateful to the millions of Facebook users that took the survey, many of them taking it multiple times over the course of two years. Thank you as well to the many researchers, nonprofit leaders and public health officials who have ensured and continue to ensure that CTIS responses inform public health decisions around the globe.


Will it be possible to access historical data after CTIS data collection ends?

Yes. We are working to archive the data that has been collected so it can continue to inform public health decisions for years to come. In line with CTIS policies and standards during the sampling period, all data will be maintained in a way that continues to preserve user privacy.

Where will the historical data be accessible?

All CTIS aggregate data will continue to be available after data collection stops on June 25, 2022 on UMD‘s Global CTIS and the Delphi Group at CMU’s US CTIS websites. Academic and nonprofit researchers may continue to request access to non-public, non-aggregated survey data for their research, and current approved data users will be able to continue accessing the non-aggregated data until their current data use agreements (DUA) expire. Researchers currently with a fully executed DUA will have the option to extend their DUA after it expires. Though no new data will be collected after June 25, 2022, Meta’s CTIS visualizations will continue to be available, and until the end of 2022, JH CCP’s COVID Behaviors dashboard will as well.