A new paper published in JAMA provides a lens into the changing infection rate of SARS-CoV-2. Given the growing yet controversial evidence regarding convalescent plasma to treat covid-19, the American Red Cross initiated national testing for donated plasma. All donated blood was tested for the SARS-CoV-2 antibodies between June 15 to August 23, 2020. Nearly 954,000 blood donations to the American Red Cross were tested for SARS-CoV-2 antibodies of which 1.8 percent were positive for antibodies. Donors were more likely to have antibodies to the SARS-CoV-2 virus if they were ages 18 to 24 years, Black or Hispanic, and located in the Northeast when compared to donors over the age of 55, who were White, and located in the West. The rate of positive blood donations increased weekly during the study period from 1.2 to 2.6 percent of all donated blood. Regionally, the greatest increase in the rate of positive blood donations over the study period was noted for those located in the South, an unsurprising finding. 

It is difficult to know if these findings are generalizable or represent previous infection rates within the United States. Additionally, those who donate blood may not represent the overall population of individuals who have had covid-19. Despite these limitations, these results are important insofar as they provide insight on infection rates among younger adults and ethnic/racial minorities, who are less likely to have been tested than other demographics.

The Centers for Disease Control and Prevention—and indeed the entire federal government—has had a controversial stance on school reopenings during the pandemic. In late July the CDC's recommendations downplayed the risk to children, and the administration threatened to withhold funding where schools did not reopen.  This week, the CDC released new recommendations that encourage localities to decide when reopening is right for them through a series of core and secondary indicators. The core indicators fall into two categories: community burden (new cases per 100,000 individuals over 14 days; percent of RC-PCR tests that are positive over 14 days) and mitigation strategies (consistent and correct mask usage; social distancing; hand hygiene and respiratory etiquette; cleaning and disinfection; contact tracing infrastructure). The CDC recommends using both community burden indicators and one mitigation assessment to determine overall infection risk. The document stresses that even medium or high-risk assessments do not mean an area must choose not to reopen, but that alternatives to in-person classes can be considered, and that even a low-risk region may see more infections.The document goes on to discuss each of the mitigation strategies in detail, as well as providing a breakdown of risk for different classroom modalities and sports activities.  CDC.