By Varun C. Anipindi

People infected with SARS-CoV-2 can experience a wide range of outcomes, ranging from asymptomatic infection to severe disease and death. While emerging evidence indicates that antibodies may represent a major correlate of protection, the specific mechanisms by which they influence overall disease outcomes is unknown.  In this pre-print, not yet peer-reviewed, Kaplonek et al. conducted an in-depth profiling of the humoral immune response to infection in a large cohort of individuals with asymptomatic, moderate, or severe disease during the acute phase of infection (0-12 days post-symptom onset)1.

Key points

  • Those who survived severe COVID-19 generated robust and highly coordinated acute antibody responses early post-infection, compared to patients that succumbed to COVID-19.
  • Antibodies generated against the conserved S2 subunit (non-RBD binding portion of the spike protein) may represent a key biomarker in distinguishing survivors and non-survivors of COVID-19.
  • Cross-reactive immunity to the S2 subunit of seasonal coronaviruses, such as OC43, (an immune response raised against the proteins of a virus that provides some level of immunity to a different virus) may be associated with the rapid maturation of SARS-CoV-2 specific antibodies, which was linked to better disease outcomes.
  • These S2-specific antibodies have the capacity to interact with Fc receptors (receptors on the surface of phagocytes involved in clearance of pathogens from the body) and may represent a key correlate of protection against death or symptomatic COVID-19 disease.

Kaplonek P, Wang C, Bartsch Y, et al. Early cross-coronavirus reactive signatures of protective humoral immunity against COVID-19. bioRxiv. 2021;2021.05.11.443609. Published 2021 May 12. doi:10.1101/2021.05.11.443609