Where Do COVID Transmissions Mostly Occur?

According to CNN's Dr. Sanjay Gupta, it does not make sense that schools are being closed while restaurants, gyms, bars and churches remain open. His argument is based on the observation that while the positivity COVID test rate in New York City is above 3 percent, the rate inside schools is below 0.2 percent. In order to avoid overwhelming hospitals, it is important to curb transmission. A total lockdown obviously comes with collateral damage on the economy. For this reason, it is imperative that the measures taken be the most effective and least damaging. Our measures need to be guided by science. And science can in fact answer the question, "Where do COVID transmissions mostly occur?". Citing a paper in Nature, Dr. Gupta lists the following as high risk COVID locations: restaurants, gyms, cafes, hotels and religious gatherings.

Above copied from CNN

Looking deeper into the details of the study, one sees that these locations also affect low-income households more than those who are socio-economic advantaged. This is shown in the following graph obtained from the paper in Nature. 

Above copied from Nature
The size of each dot represents the average number of visits per capita made to the category

In Chicago, transmissions in churches are more prevalent among the low-income than among the wealthy. Visits per capita are not highest in churches, but the average transmission rate among low income is highest.  The same is true for full-service restaurants and hotels. With these commercial venues, most of the cases are most likely happening with workers, who have no real choice but to show up to work. 

Addressing the pandemic is not only a health issue, but an economic one as well. With this in mind, a more appropriate measure probably lies somewhere in the middle. Again, science likewise can offer a guide. Here is the graph showing how limiting occupancy can effectively reduce transmission.

Above copied from Nature

Capping occupancy does not always translate to the same percentage loss in visits. A 50% cap, for instance, is about a 10% loss in visits and yet, more than 25% of transmissions are avoided. To reduce the number of infections by a factor of two, a 30% cap in occupancy is needed, which translates to about 25% reduction in visits. This is where it becomes obvious that action at the Federal level is required. These venues need to cap their occupancy in order to control the spread of the coronavirus while we wait for a vaccine, but this can only be done without the risk of bankruptcy, which can be avoided by providing sufficient financial aid. These businesses and their employees need financial support for these measures to be taken. Children are not going into their classrooms. And one of the main reasons is federal inaction.