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Rapid real-time tracking of non-pharmaceutical interventions and their association SARS-CoV-2 positivity: The COVID-19 Pandemic Pulse Study

Our take —

Though causal relationships between individual behaviors and SARS-CoV-2 infection cannot be established in this cross-sectional survey, available as a preprint and thus not yet peer reviewed, the survey tool may be useful for future longitudinal studies to evaluate the role of individual behaviors in transmission dynamics. Mask use and social distancing were associated with lower rates of SARS-CoV-2 test positivity, while more frequent travel, especially via public transportation or to places of worship, were associated with increased SARS-CoV-2 test positivity. While plausible, these results should be considered cautiously in light of several study limitations.

Study design


Study population and setting

The study included 1,030 individuals (median age: 43 years, 55% female) from the US state of Maryland who participated in an online survey between June 17 and June 28, 2020, shortly after Stage Two of Maryland’s phased re-opening plan began. The survey was designed to evaluate adoption of non-pharmaceutical interventions (social distancing and mask use), travel, access to SARS-CoV-2 testing, and SARS-Cov-2 test results. The survey was distributed through an online platform (Dynadata), equipped with security checks, quality verifications, and preset quotas for age, gender, race/ethnicity, and income to accrue a sample representative of the Maryland population. Participants were excluded if they were less than 18 years old, currently resided outside the state of Maryland, did not complete the survey, or did not respond to ever being tested for SARS-CoV-2 (the survey was distributed to 2,322 individuals, 1,466 responded to at least 1 survey question, and 1,030 met all inclusion criteria).

Summary of Main Findings

Sociodemographic characteristics were broadly representative of Maryland’s population. During the prior two weeks, 96% of participants left their home at least once: 92% travelled for essential services, 66% visited friends/family, 49% went to an indoor venue (bar, restaurant, salon), and 25% went to an outdoor venue (pool, beach). Practicing of social distancing increased with age, and mask use was least common among white individuals. In all, 55 participants self-reported ever testing positive for SARS-CoV-2 in the past, and in the prior 2 weeks, 62/102 participants who wanted/needed a SARS-CoV-2 test received one, of whom 18 tested positive. In multivariable analyses, more frequent use of public transportation and more frequent visits to a place of worship were strongly and positively associated with ever testing positive for SARS-CoV-2, whereas adoption of social distancing was negatively associated with a positive test.

Study Strengths

Survey distribution methods allowed for rapid and secure data collection. The study population appeared to be broadly representative of the Maryland population with respect to demographic variables and self-reported SARS-CoV-2 positivity rates counts in Maryland. Some sensitivity analyses were conducted.


Self-selection into the study population and the requirement of participants to have an internet connection limit the generalizability of the results. Additionally, because data were collected cross-sectionally, it cannot be established that self-reported behaviors preceded SARS-CoV-2 test results. For example, some individuals who previously tested positive and recovered from SARS-CoV-2 may believe they are immune, thus traveling more often and practicing less social distancing and mask use. Unadjusted sensitivity analyses restricted to self-reported SARS-CoV-2 test positivity in the previous two weeks demonstrated somewhat similar results in the main analysis, but the protective association between social distancing and test positivity was not observed. However, even in these analyses, temporal relationships cannot be established. Self-selection into the study and self-reporting of behaviors and test results may introduce bias, underestimating the association between behaviors and infection rates if individuals with perceived “riskier” behaviors are less likely to participate, inaccurately over-report non-pharmaceutical interventions, or are less likely to report testing positive.

Value added

In this study, a rapid and cost-efficient online survey tool was used to evaluate the association between social distancing, mask use, and SARS-CoV-2 test results.

This review was posted on: 14 August 2020