Immune cell residency in the nasal mucosa and COVID-19 severity across the age range (preprint)

Severe coronavirus disease of 2019 (COVID-19) positively correlates with age (Centers for Disease Control), develops after progression of infection from the upper airway to the lower respiratory tract (LRT), and can worsen into acute respiratory distress syndrome (ARDS). Why children seem to be less likely to develop severe disease remains unclear. As the nasal mucosa (NM) is the first site of contact and defense for respiratory pathogens such as SARS-CoV-2 before dissemination to the LRT, we hypothesized that differences in this tissue across the age range may help explain the disparity in COVID-19 severity. To this end, we profiled NM samples across the lifespan in health and disease. We find that global transcriptomic changes including the expression of SARS-CoV-2 and coronavirus-associated receptors and factors are not correlated with age or the novel virus type, since pediatric NM cells mount similar antiviral response to both SARS-CoV-2 or Influenza B. Rather, we find immune cell residency in NM decreases dramatically with age especially cells of the innate immune system. This includes a resident-memory-like T cell subset with antiviral properties. These observations give plausible biological explanation to the observed clinical differences in disease spectrum and provide a foundation for future experimental studies.

Antibody responses boosted in seropositive healthcare workers after single dose of SARS-CoV-2 mRNA vaccine (preprint)

Current guidelines recommend that individuals who have had COVID-19 should receive the identical vaccine regimen as those who have not had the infection. This includes two doses of the mRNA platform vaccines (BNT162b2/Pfizer; mRNA-1273/Moderna) that are approved for use in the United States. In this brief report, we show that after a single dose of the Pfizer SARS-CoV-2 vaccine, individuals that had prior SARS-CoV-2 infection had significantly higher antibody levels than individuals that had no history of infection. This provides the rationale for changing vaccination policy to deliver only a single dose to individuals with recent SARS-CoV-2 infection that may free up additional doses for individuals that have no preexisting immunity to the virus. Future study of other immune parameters such as T cell response and durability of immune response should be rapidly undertaken in individuals that had COVID-19 prior to vaccination.