In San Francisco, California, only half of reachable COVID-19 index cases between April 13 and June 5, 2020, reported >1 close contacts, 84% of whom were notified of their exposure. Of notified contacts, 45% were tested for SARS-CoV-2 infection; 26%…

This study provides reasonably strong evidence that Trump 2020 campaign rallies caused a substantial number of COVID-19 cases in the US counties where they took place, although the precise number of cases caused is difficult to estimate. The methods were…

Although in-person voting for the U.S. presidential election concluded on November 3, 2020, there will be a handful of runoff elections around the U.S. through January 2021, including a high-profile election in Georgia. This study surveyed 522 election poll workers…

New Zealand is one of the only countries in the world to achieve rapid, sustained success in containing its COVID-19 epidemic. This paper broadly describes how the extinguishing of the epidemic coincided with a rapidly amplified series of nationwide non-pharmaceutical…

In Arizona, a spike in COVID-19 cases coincided with the relaxation of both a statewide stay-at-home order and business closures; daily case growth plateaued and was reversed following the introduction of local mask mandates, re-closure of non-essential businesses, and additional…

This survey, conducted once before the COVID-19 pandemic (October 2019) and once during the pandemic (June 2020), indicated that self-reported handwashing behaviors increased among U.S. adults. Handwashing rates improved particularly after coughing, sneezing, or blowing one’s nose, as well as…

The number of daily trips taken by residents of major Chinese cities correlated highly with the estimated reproductive number of SARS-CoV-2 in the early part of the epidemic, but the correlation declined, and even became negative in mid-February 2020 after…

In two neighboring North Carolina counties, no close contacts were identified in a large proportion of confirmed COVID-19 cases, over one-fourth of enumerated close contacts were unreachable, and there was a long delay between case identification and contact notification. When…

This study compared two protocols for facility-wide SARS-CoV-2 testing at 28 long-term care facilities: 1) testing that occurred in response to reported cases; and 2) preventive testing of residents and staff before any reported cases. Preventive testing was associated with…

Test, trace, and isolate protocols are a crucial part of the UK COVID-19 response. In this large survey, available as a preprint and thus not yet peer reviewed, knowledge of COVID-19 symptoms was fairly poor, and there was a large…

In one Chinese hospital, the proportion of COVID-19 patients who wore eyeglasses was considerably lower than a historical estimate for the prevalence of myopia in another Chinese province. The authors speculate that eyeglasses may provide some protection from SARS-CoV-2 infection,…

This proof-of-concept study, available as a preprint and thus not yet peer reviewed, evaluated uptake and effectiveness of SwissCOVID, a decentralized digital contact tracing application (i.e., app) that maintains individual user privacy, using multiple independent data sources from Switzerland. Results…

This preprint, which has not yet been subjected to peer review, used both case counts and deaths in an age-specific model of SARS-CoV-2 transmission in New York City. The authors estimate that the reproduction number of the virus decreased dramatically…

This study demonstrates that the introduction of universal masking, followed by universal testing/isolation algorithm for suspected COVID-19 cases, in a tertiary care facility were associated with reductions in the rate of healthcare workers’ exposures to unmasked individuals and to aerosol-generating…

In contrast to a recent report of high attack rates of SARS-CoV-2 among children and staff in a Georgia overnight summer camp, this report of over one thousand attendees of four Maine overnight camps did not identify any secondary transmissions…

This study, which was available as a preprint and thus had not yet been peer reviewed, uses county-level SARS-CoV-2 testing data to show that the Sturgis motorcycle rally likely led to substantial increases in cases in the local community where…

This study reported on results of a new protocol for channeling incoming prisoners through a standardized protocol of testing and quarantine. In contrast to the mass outbreaks seen in many other U.S. correctional facilities, only two cases were observed after…

This study finds that people in Germany are more likely to wear masks given a mandatory mask policy rather than a voluntary one, and that such a mandatory policy would be viewed as more fair.

This study, available as a preprint and thus not yet peer reviewed, evaluated the impact of 13 different non-pharmaceutical interventions on the time varying reproductive number across 130 countries and territories through June 2020. Impact was assessed using a wide…

In this study of healthcare workers providing SARS-CoV-2 counseling to thousands of asymptomatic family contacts of infected cases in India, 12/62 tested positive before the introduction of plastic face shields, but 0/50 tested positive after face shields were introduced. Masks,…

This study conducted qualitative in-depth interviews with 30 informal settlement dwellers receiving food assistance in Tshwane, South Africa during a COVID-19 lockdown. Interviews revealed the deleterious economic, social, and health-related impacts of COVID-19 lockdown policies on low-income households and communities.

Incidence of SARS-CoV-2 infection was high in Padua, Italy during the spring of 2020. This study documents universal screening and testing of newborns, parents, and staff at a neonatal ward in Padua during this period. Five parents and staff members…

In the U.S. state of Maine, the overwhelming majority of COVID-19 contacts who participated in symptom monitoring opted to do so with an automated system using text messages or the web. Contacts who did not participate were not enumerated, making…

This study found that adherence to self-isolation measures among Japanese workers experiencing cold-like symptoms was low despite guidelines to self-isolate if ill. Availability of work-from-home options, paid sick leave, and home delivery options of groceries and other necessities are likely…

This study objective was to describe the prevalence of SARS-CoV-2 among pregnant women presenting to the hospital for delivery. Using universal testing, 375 women were tested for infection across four hospitals, of which 71 tested positive (18.6%), and 64 of…

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…

Younger respondents, compared to older respondents, perceived higher risks for SARS-CoV-2 infection, death, and hospitalization due to COVID-19 for all age groups. Those that perceived greater average COVID-19 risks for others were more likely to favor stricter lockdowns. Those that…

This analysis of smartphone geolocation data associated with 6,644 nursing homes across 23 U.S. states, published as a working paper and not yet peer reviewed, showed that facilities are highly connected, with 7% of phones appearing in a given facility…

As other studies have shown, wealthier counties and census tracts were markedly more likely to be able to socially distance compared to less wealthy counties and census tracts.

In a time-series analysis accounting for variation in population composition and timing of other non-pharmaceutical interventions (e.g., shelter-in-place orders, suspension of mass gatherings), substantial COVID-19 incidence and mortality reductions were attributed to school closures. These were most effective when implemented…

This is a contact tracing study based in Trento, Italy, published as a preprint and thus not yet peer reviewed. There were 2,812 cases and 6,690 contacts. There was an overall secondary attack rate of 13.3%, with the highest secondary…

Face coverings worn by the general public likely limits the spread of COVID-19; however, there is limited real-world data on their effectiveness. This study shows that face coverings resulted in no onward transmission from two hair stylists with COVID-19 symptoms…

Between April and May, 2020, cloth face covering use outside the home increased by nearly 15% and across demographic groups in a representative online sample of U.S. adults. Theorized antecedents of behavior change (e.g., perceived social norms, personal agency, outcome…

This study compared the proportion of symptomatic health care workers (HCWs) testing positive for COVID-19 before and after universal masking policies were implemented within the health system. Before universal masking, the positivity rate was increasing rapidly, and following universal masking,…

Physiological data derived from wearable technology in 24 US COVID-19 patients revealed latent physiological disturbance patterns—including heightened heart rate, decreased physical activity, and increased sleep duration—prior to symptom onset. A wearable technology detection algorithm correctly identified physiological abnormalities associated with…

Contact tracing conducted by the Seoul Metropolitan Government and the Seoul Metropolitan Police Force due to an outbreak of COVID-19 among those who attended nightclubs in the Itaewon area from April 30 to May 6, 2020 resulted in 246 cases…

The study shows that with a 14-day lockdown in the Italian city of Vo’, the prevalence of SARS-CoV-2 infection decreased from 2.6% to 1.2% in the general population. 42.5% of those that tested positive reported minimal or no symptoms consistent…

This study, available as a preprint and thus not yet peer reviewed, conducted direct observations of 12,588 individuals in Baixada Santista, Brazil. The study found suboptimal (<50%) and inappropriate (42.7%) face mask use in public settings.

Little evidence has emerged so far regarding the effectiveness of mask-wearing (on the part of infected individuals) in reducing transmission of SARS-CoV-2. In this small study from China, people with COVID-19 who reported wearing masks before they felt symptoms infected…

In this US-based study, state-level mask mandates were associated with a decline in the growth rate of COVID-19 cases; this estimated effect grew larger with time after the mandate. Actual mask use was not measured, and results rely on trends…

This study, available as a preprint and thus not yet peer reviewed, found that among users of a symptom tracking app for COVID-19 who regularly reported their symptoms until either hospitalization or symptom improvement, those reporting more symptoms within five…

Using setting- and disease-specific social contact data from the UK, authors demonstrated that combined test and trace strategies could reduce SARS-CoV-2 transmission more than self-isolation or mass testing alone (60-65% reduction compared to a 2-30% reduction). App-based contact tracing was…

This study, a preprint and thus not yet available for peer review, presented direct observation of 3,271 patrons exiting grocery stores in 20 Wisconsin counties. It revealed fewer than half of shoppers donned face coverings in public with substantial variability…

An online survey administered to 502 adults in the United States showed suboptimal knowledge of safe and appropriate household cleaning and disinfection practices. The survey also demonstrated concerning levels of unsafe cleaning and disinfection behaviors, resulting in adverse but minor…

While masks most likely prevent community spread of COVID-19, this highly flawed paper provides no evidence on mask effectiveness at the population level. The study also provides no information to demonstrate that airborne transmission-- let alone “long-range airborne transmission”-- is…

This major study of national, regional, and local non-pharmaceutical interventions in China, the United States, Italy, South Korea, Iran, and France estimated that the combination of all infection control measures substantially slowed the growth of the COVID-19 epidemic. Over 60…

This study provides credible estimates that by May 4, 2020, the 11 European countries in this study had achieved control of the COVID-19 epidemic by bringing the reproduction number below 1, after 3.2% to 4.0% of the population had become…

This pilot study in eight homeless shelters in Canada demonstrated the apparent effectiveness of aggressive testing and control measures in preventing a large-scale outbreak. Several of the measures may be applicable in a variety of congregate settings: reducing bed density,…

This case-control study from Spain and Italy, available as a preprint and thus not yet peer reviewed, provides the first large-scale evidence of host genetic influence in severe COVID-19 disease, and identifies biological targets for further investigation. This analysis was…

The declaration of a public health emergency on February 23, 2020, and implementation of various physical distancing measures on March 23, 2020 in the absence of a national lockdown, corresponded to substantial reductions in COVID-19 transmission in South Korea, suggesting…

Active surveillance using text-messaging may be an effective and efficient way to monitor exposed asymptomatic contacts to COVID-19. This study assessed the potential utility of such an automated text-messaging monitoring system in Ireland. While the overall response rate to daily…

To date, there is no evidence from randomized trials regarding the effect of wearing face masks on the risk of acquiring infection from SARS-CoV-2. In the absence of this urgently needed data, this systematic review and meta-analysis provides evidence, with…

This study was available as an online working paper, and thus was not yet peer reviewed. Black Lives Matters protests in urban areas resulted in a net increase in social distancing within the community. Protests did not result in increased…

Using daily laboratory-confirmed case counts, this study evaluated the association between control measures implemented in China and the spread of COVID-19 beyond Wuhan. Control measures such as the Wuhan travel ban and implementation of Level 1 Emergency response were associated…

Results from this study, available as a preprint and thus not yet peer reviewed, suggest that even relatively small changes in the timing of stay-at-home measures at the beginning of the COVID-19 epidemic in the United States could have made…

During the first seven weeks of a symptom monitoring program for inbound travelers to the United States from China and Iran, the California Department of Health reviewed and forwarded 12,061 traveler records, many containing errors or omissions, to 51 health…

Correctional/detention facilities are at greater risk of COVID-19 outbreaks due to the confined physical spaces, high contacts between inmates, and logistical and security issues that make it difficult to implement recommended distancing measures. This study does not report details of…

An epidemic model of COVID-19 spread in Germany revealed noteworthy reductions in COVID-19 epidemic growth following the implementation of sequential non-pharmaceutical interventions, including suspension of large public gatherings, business and school closures, and a nationwide contact ban.

Among 18,401 users of a symptom-tracking app in the UK and US, the loss of smell and taste (as well as cough, fatigue, and skipped meals) was strongly associated with a positive SARS-CoV-2 test result. Although a symptom-based predictive model…

In this study available as a preprint and thus not yet peer reviewed, social distancing in the 25 U.S. counties with highest COVID-19 incidence was correlated with a decrease in the growth rate of COVID-19 cases, with an estimated 9…

An online survey published as a preprint and thus not yet peer-reviewed, found that US adults expressed a high willingness to test for COVID-19 at home, at drive-through test sites, and at clinics if they developed illness symptoms, with a…

Early evidence from a large online survey conducted in four European countries and the United States suggests a high willingness to install or keep a digital contact tracing application on a mobile device, with few differences across sub-populations (i.e., age,…

Preliminary results from this study of real-time COVID-19 symptom data collected through an app suggests that app-based symptom tracking may be useful for predicting spikes and drops in new cases several days in advance of other more traditional measures (e.g.…

This study used comprehensive data from China on population mobility patterns and SARS-CoV-2 case detection to estimate the individual and combined impact of non-pharmaceutical interventions (NPIs) on SARS-CoV-2 spread. Results showed that rapid detection and isolation of cases through contact…

In a survey of households in China in which one member was diagnosed with COVID-19, mask use — both by the infected individual and by uninfected family members, both before and after symptom onset — appeared to provide protection against disease…

This is an important non-peer reviewed study with important flaws. The question of whether children infected with SARS-CoV-2 can transmit the infection as readily as adults is crucial to decisions about school closures and societal re-opening. Although the authors report…

Adolescents and young adults, particularly those aged 20-24 years, represented an increasing share of reported COVID-19 cases in Germany during late March and early April, 2020. Although results are consistent with this age group exhibiting less adherence to social distancing…

As a result of social distancing measures, total interpersonal contacts dropped significantly in China, and mixing among school-aged children was almost entirely eliminated. The study estimates that school closures by themselves would reduce peak incidence by a considerable amount, though…

California has experienced a lower COVID-19 case and mortality burden relative to other states (e.g., New York) with early community transmission, leading to speculation about the role of statewide policy in the evolution of the epidemic. These results suggest that…

This study evaluated the effect of the Wuhan travel ban on the spread of COVID-19 within Mainland China and internationally. Using airport closures and airline suspensions, results from this model suggest that reducing long-range travel from Wuhan by up to…

This study convincingly shows that a large, diverse package of surveillance and containment measures effectively suppressed transmission of both COVID-19 and influenza in Hong Kong. However, it is not possible to disaggregate effects of any particular intervention, which limits the…

Local, state, and national policies designed to encourage physical distancing preceded substantial but variable reductions in the percentage of residents leaving home each day in New York, San Francisco, Seattle, and New Orleans. The marginal impacts of these policies on…

This study estimated that a coordinated, nationwide policy encouraging individuals to stay at home would have considerably decreased the number of COVID-19 cases in the US. Stay-at-home and shelter-in-place ordinances likely achieved peak effectiveness in mitigating COVID-19 transmission nearly one…

This small study provided limited new information given our current state of knowledge. It is clear that additional precautions (wearing gowns, N95 masks, eye protection, and using air-purifying respirators) are needed to prevent health care workers from acquiring COVID-19 from…

Statewide social distancing measures in the United States have been effective at reducing the daily growth rate of COVID-19, but further analyses are needed to understand which measures were most effective.

Adherence to social distancing recommendations in the United States, as measured by reductions in daily travel, was associated with socioeconomic status, race/ethnicity, and voting patterns. It is not clear how representative the data are, and unmeasured confounding may be present.

Using mathematical modeling, the authors show that containment policies and social distancing measures effectively slowed the growth in confirmed COVID-19 cases in China.

Using survey data, this study showed that in-person contacts dramatically declined following implementation of strict social distancing measures in the UK, to levels that would substantially slow epidemic growth. Participants in this study were recruited by email and may have…

This study highlights an overlooked cost of school closures: possible increases in COVID-19 mortality associated with health care workers leaving work because of increased child care burden. The model ignores several potentially important dynamics, and is reliant on assumptions with…

The severe lockdown measures put in place in Wuhan and all other cities in Hubei province in China, enacted early in the epidemic, slowed the exportation of COVID-19 from mainland China, but were insufficient to stop transmission globally. The author's…

Reduced movement in the greater Seattle area has been observed, with more people staying at home, presumably in response to the broad array of social distancing measures progressively announced since March 5, 2020. Reduced movement does not necessarily equate to…

Our take — This non peer-reviewed study found that social distancing drastically reduced transmission in Wuhan and Shanghai. Modeling suggests that school closures can significantly reduce overall transmission and disease burden, even though susceptibility to infection was lower among school-aged…

In Singapore, implementing aggressive surveillance and containment measures (e.g., compulsory quarantine for all asymptomatic close contacts) for SARS-CoV-2 was associated with a steep drop in the time between symptom onset and case isolation between the beginning of January and the…

Mobility out of Wuhan led to strong transmission chains in other parts of China. The strict ban on travel in or out of Wuhan reduced transmission in the early stage of the outbreak, when importation was the dominant source of…

This modeling study used data from China, Italy, and the UK to determine the potential impact of non-pharmaceutical interventions on the epidemic in the US and UK. Population-wide social distancing was found to be the most impactful intervention, and models…