Rapid real-time tracking of non-pharmaceutical interventions and their association with SARS-CoV-2 positivity: The COVID-19 Pandemic Pulse Study
Authors: Clipman Steven J. , Wesolowski Amy P. , Gibson Dustin G. , Agarwal Smisha , Lambrou Anastasia S. , Kirk Gregory D. , Labrique Alain B. , Mehta Shruti H. , Solomon Sunil S. 
Published: August 2020

Background

Current mitigation strategies for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rely on population-wide adoption of non-pharmaceutical interventions (NPIs). Collecting demographically and geographically resolved data on NPIs and their association with SARS-CoV-2 infection history can provide critical information related to reopening geographies.

Methods

We sampled 1,030 individuals in Maryland from June 17 – June 28, 2020 to capture socio-demographically and geographically resolved information about NPI adoption, access to SARS-CoV-2 testing, and examine associations with self-reported SARS-CoV-2 positivity.

Results

Median age of the sample was 43 years and 45% were men; Whites and Blacks/African Americans represented 60% and 23%, respectively. Overall, 96% of the sample reported traveling outside their home for non-employment related services: most commonly cited reasons were essential services (92%) and visiting friends/family (66%). Use of public transport was reported by 18% of respondents. 68% reported always social distancing indoors and 53% always wearing masks indoors; indoor social distancing was significantly less common among younger vs. older individuals, and race/ethnicity and income were significantly associated with mask use (p<0.05 for all). 55 participants (5.3%) self-reported ever testing positive for SARS-CoV-2 with strong dose-response relationships between movement frequency and SARS-CoV-2 positivity that were significantly attenuated by social distancing. In multivariable analysis, history of SARS-CoV-2 infection was negatively associated with the practice of social distancing (adjusted Odd Ratio [aOR]: 0.10; 95% Confidence Interval: 0.03 – 0.33); the only travel associated with higher likelihood of SARS-CoV-2 infection was use of public transport (aOR for ≥7 times vs. never: 4.29) and visiting a place of worship (aOR for ≥3 times vs. never: 16.0) after adjusting for social distancing.

Conclusions

Using a rapid cost-efficient approach, we highlight the role of movement and social distancing on SARS-CoV-2 transmission risk. Continued monitoring of NPI uptake, access to testing, and the subsequent impact on SARS-CoV-2 transmission will be critical for pandemic control and decisions about reopening geographies.

Key Points

What we did

We utilized an online survey approach to sample residents of Maryland consistent with the distributions of age, gender, race/ethnicity, and income in the state.

We asked questions about places (and the frequency) visited for essential and nonessential services in the prior 2 weeks, practice of non-pharmaceutical interventions (NPIs) while visiting various places, and access to SARS-CoV-2 testing.

We characterized how movement and adoption of NPIs differed by key demographics (age, race, gender, income) and how these were associated with self-reported SARS-CoV-2 positivity.

What we found

96% of the sample reported traveling for either essential or non-essential services in the prior 2 weeks; 82% reported traveling for non-essential services.

The adoption of NPIs varied by age, race/ethnicity, and income.

Self-reported SARS-CoV-2 positivity was highest among Latinos followed by Blacks/African Americans and then Whites.

The more frequently a person traveled/visited places for non-essential services, the more likely they were to report ever having tested positive for SARS-CoV-2.

The strict practice of social distancing was associated with a lower likelihood of ever having tested positive for SARS-CoV-2; moreover, strict social distancing attenuated the association between most forms of movement and SARS CoV-2 positivity

Using public transport and attending places of worship remained associated with a higher likelihood of having tested positive for SARS-CoV-2 even when practicing social distancing.

About 70% of people who wanted a SARS-CoV-2 test were able to get a test but there were delays of a week or more from wanting a test to getting a result among the majority of the sample.

What it means

The more people move the more likely they are to test positive for SARS-CoV-2; if you must travel, practice social distancing as it reduces the likelihood of testing positive.

Avoid public transport to the extent possible.

Strategies to reduce time from wanting a test to getting a result are critical to enhance early case detection and isolation to curb transmission.