Over 150,000 restaurants, hotels in 8 US states are coronavirus super-spreaders, can trigger second wave: Study
As businesses across the US start to reopen in phases, researchers warn that full-service restaurants, hotels, and fast-food outlets could become super-spreaders — where people are most likely to get infected with Covid-19 — during the coronavirus pandemic, triggering a potential second wave. Around 156,307 individual businesses in eight states have been identified by researchers as super-spreaders.
Businesses with more visitors that stay for longer and are more densely packed are likely to have higher risks of transmission, shows analysis. This may have important implications for states and policymakers as it will enable them to help plan how to reopen these "super-spreader businesses" in the safest way possible, says the team. It includes experts from Beth Israel Deaconess Medical Center, Boston, Pennsylvania State University, Pennsylvania, University of Pennsylvania, Philadelphia, and Janssen Research & Development, New Jersey.
"There is a pattern to the events and places that have a high risk of transmission that can be deemed as super-spreaders. They are often indoor events with people in extremely close proximity to each other for a long duration of time. The risk of transmission in a closed establishment is 18.7 times higher than in an event in an open-air establishment. Even though the public and states are ready to reopen the economy, experts cautioned on the resurgence of the virus and death tolls if we open our economy prematurely," says the team in their findings.
They add, "Given the empirical evidence on the potential impact of super-spreaders in the spread of Covid-19, it is crucial to evaluate which businesses, events, establishments, and industries should reopen first and which ones may have a higher risk of spreading the virus."
The study focused on 187 counties in 8 states, with a total population of 73,894,989. This includes Massachusetts, Rhode Island, Connecticut, New Hampshire, Vermont, Maine, New York, and California. The researchers examined traffic to 918,094 businesses from January 1, 2019, to May 31, 2019. They also analyzed Covid-19 cases in these counties from January 22, 2020, to May 22, 2020.
The team created a Covid-19 business transmission risk index, which was built using data on visitors per square foot, frequency of visits and the average duration of visits. Visitors per square foot account for how densely visitors are packed into businesses. The researchers found that higher densities of super-spreader businesses are associated with higher rates of Covid-19 cases.
"This classifies 156,307 individual businesses as super-spreaders out of a total of 918,094 businesses. In our sample, there was an average of 28.83 cumulative cases of Covid-19 per 10,000 by May 22, 2020. The average density of super-spreader businesses in a county was 16.29 per 100 businesses. On average, 18.55% of a county was above the age of 65, 84.86% was white, 2.95% was black, and 8.96% was below the federal poverty line. The average population density of a county was 299.49 people per square mile."
The most common type of super-spreader business in the sample is full-service restaurants. “These are restaurants where you are seated, typically have a server, and pay after your meal is completed. There are 116,605 full-service restaurants in our sample,” says the study.
The second most common type of super-spreader business is limited-service restaurants with 26,196 in the sample. These are restaurants where one may pay at a counter before the meal. This would include fast-food, delicatessens, sandwich shops, takeout restaurants, and pizza delivery. The third most common type of super-spreader business are hotels (except casino hotels) and motels with 13,432 of these businesses, says the analysis.
“Our results suggest that an increase in super-spreader businesses by 1 percentage point results in a 5% increase in Covid-19 cases, all else equal. Businesses that are more densely packed may have a higher risk of Covid-19 transmission. The average duration of visits accounts for the length of time visitors are spending in a business. Businesses, where visitors linger for longer periods of time, could be riskier for Covid-19 transmission than businesses where visitors are quickly in and out of the business," the findings state.
The team says that knowing the density of super-spreader businesses will be very useful for policymakers. When planning to reopen, policymakers can consider more options to help restaurants reopen while mitigating the risk to the public, they explain. "This could include more outside seating, limitations on the number of visitors at a time, and monitoring traffic to potential super-spreader businesses. This study can also be useful for hospital decision-makers. Knowledge of the density of super-spreader businesses and monitoring traffic to these businesses may help hospitals prepare for a potential second-wave if traffic increases to these businesses very quickly," say researchers.
Over 1,681,410 coronavirus cases have been reported in the US as of May 27, and more than 98,920 have died in the Covid-19 pandemic, according to data compiled by Johns Hopkins.