SARS-CoV-2 infection of the oral cavity and saliva
Despite signs of infection—including taste loss, dry mouth and mucosal lesions such as ulcerations, enanthema and macules—the involvement of the oral cavity in coronavirus disease 2019 (COVID-19) is poorly understood. To address this, we generated and analyzed two single-cell RNA sequencing datasets of the human minor salivary glands and gingiva (9 samples, 13,824 cells), identifying 50 cell clusters. Using integrated cell normalization and annotation, we classified 34 unique cell subpopulations between glands and gingiva. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral entry factors such as ACE2 and TMPRSS members were broadly enriched in epithelial cells of the glands and oral mucosae. Using orthogonal RNA and protein expression assessments, we confirmed SARS-CoV-2 infection in the glands and mucosae. Saliva from SARS-CoV-2-infected individuals harbored epithelial cells exhibiting ACE2 and TMPRSS expression and sustained SARS-CoV-2 infection. Acellular and cellular salivary fractions from asymptomatic individuals were found to transmit SARS-CoV-2 ex vivo. Matched nasopharyngeal and saliva samples displayed distinct viral shedding dynamics, and salivary viral burden correlated with COVID-19 symptoms, including taste loss. Upon recovery, this asymptomatic cohort exhibited sustained salivary IgG antibodies against SARS-CoV-2. Collectively, these data show that the oral cavity is an important site for SARS-CoV-2 infection and implicate saliva as a potential route of SARS-CoV-2 transmission.
Assessment of protection against reinfection with SARS-CoV-2 among 4 million PCR-tested individuals in Denmark in 2020: a population-level observational study
The vast majority of people who recover from Covid-19 remain protective immunity from the virus for at least six months, researchers reported on Wednesday in a large study from Denmark. The study revealed protective immunity to be approximately 80–83% in people younger than 65 years. We found no difference in immunity over the study period. Among those aged 65 years and older, immunity was estimated to be approximately 47%.
Shortly after SARS-CoV emerged at the turn of the 21st century, the spike (S) protein (particularly in its prefusion [native] conformation) was identified as the immunodominant antigen of the virus. Evaluation of patients with SARS-CoV-2 revealed that binding and neutralizing antibodies primarily target the receptor-binding domain of the S1 subunit.
SARS-CoV-2 Variants of Concern in the United States—Challenges and Opportunities
. SARS-CoV-2, like other RNA viruses, constantly changes through mutation, with new variants occurring over time. Generally, when new variants become more common, they do so because of some selective advantage to the virus.
The US Regulatory System and COVID-19 Vaccines The Importance of a Strong and Capable FDA
For many in public health and medicine, the coronavirus disease 2019 (COVID-19) pandemic in the US has been a frustrating journey from one disappointment to the next: late access to testing, insufficient staff and inadequate funding for contact tracing, jumbled communications, and, at the end of 2020, a chaotic launch of vaccination efforts.