Researchers from the Whitehead Institute for Biomedical Research in Cambridge found that DNA copies of SARS-CoV mRNA sequences will integrate into human genome (HEK293T cells) via ancient long interspersed element (LINE)-1 retroposition mechanism to form a chimeric gene sequence in potential host genome. This finding suggests further studies are needed to understand how genome integration affects disease course, future antibody reactions, detectable levels via immunohistochemistry, and future vaccine and anti-viral therapies.

This article by a JAMA journalist discusses a series of case studies that illustrate sustained infection in immunocompromised individuals. She discusses how these individuals are often contagious for an extended period of time and cites research that shows that the virus evolved and adapted to treatment over a 3-month-long infection in an immunocompromised individual. She suggests that prolonged infections and suboptimal therapies can provide the evolutionary pressures for variants to emerge, which could produce a more transmissible virus and/or result in variants that are resistant to therapies or vaccines. She discusses how many researchers believe that the current SARS-CoV-2 variants of concern first arose in immunocompromised hosts and emphasizes that the healthcare community must find how best to treat COVID-19 in severely immunosuppressed patients to prevent further variants from arising.

A review article conducted by researchers affiliated with Harvard University, University of Michigan, and HOK Architects in Chicago, Illinois provide rational for increasing the current ventilation and filtration standards for indoor spaces levels closer to hospital standards (eTable), since SARS-CoV-2 outbreaks have been largely associated with time spent indoors and low-level ventilation. Higher ventilation and filtration rates allow for rapid removal of particles from indoor air to lessen the duration of respiratory aerosols and far-field transmission (within same room by beyond 6 feet) among room occupants. Considerations for implementing these strategies include cost, minimal impact on close-contact transmission, use in spaces where masks are not worn all the time, and scale of ventilation/filtration to the amount of occupants in the rooms. Improved ventilation and filtration strategies should be a continued emphasis in buildings even after the pandemic as a holistic risk reduction strategy.

A cross-sectional study conducted at the University of Colorado Boulder from August 27, 2020 to December 11, 2020 testing 72,500 saliva samples from non-symptomatic individuals using qRT-PCR identified 1,405 positive COVID-19 cases. Comparison to published data of symptomatic, primarily hospitalized patients showed similar distributions of viral load (Figure 2). In both this campus population and published hospitalized patient populations, just 2% of individuals were found to harbor 90% of circulating virions (Figure 3), showing an asymmetric virion distribution. Authors highlight the importance of community screening for these viral superspreaders and the need to inform them of their infections status quickly to prevent further spread.

An editorial article conducted by researchers affiliated with Columbia University Irving Medical Center in New York investigated a study performed in Sweden by Norman et al involving 88159 infants born to 87005 mothers between March 11, 2020 and January 31, 2021, in which there was a 2.6% maternal SARS-CoV-2 positivity rate. This study showed maternal SARS-CoV-2 infection in pregnancy to be associated with higher risk of newborn complications, with the risk increasing with COVID-19 disease severity. However, the incidence of positive SARS-CoV-2 PCR tests in infants was low (0.9%) with no cases progressing to pneumonia. This study provides reassuring data of low risk of neonatal infection, morbidity, and mortality, however more information is needed overall on short and long-term outcomes related to children with in utero exposure to SARS-CoV-2.