Biology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the humoral immunoresponse: a systematic review of evidence to support global policy-level actions and research.

Background: Both population-level epidemiological data and individual-level biological data are needed to control the coronavirus disease 2019 (COVID-19) pandemic. Population-level data are widely available and efforts to combat COVID-19 have generated proliferate data on the biology and immunoresponse to the causative pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, there remains a paucity of systemized data on this subject.

Objective: In this review, we attempt to extract systemized data on the biology and immuno-response to SARS-CoV-2 from the most up-to-date peer-reviewed studies. We will focus on the biology of the virus and immunological variations that are key for determining long-term immunity, transmission potential, and prognosis.

Data Sources And Methods: Peer-reviewed articles were sourced from the PubMed database and by snowballing search of selected publications. Search terms included: "Novel Coronavirus" OR "COVID-19" OR "SARS-CoV-2" OR "2019-nCoV" AND "Immunity" OR "Immune Response" OR "Antibody Response" OR "Immunologic Response". Studies published from December 31, 2019 to December 31, 2020 were included. To ensure validity, papers in pre-print were excluded.

Results: Of 2 889 identified papers, 36 were included. Evidence from these studies suggests early seroconversion in patients infected with SARS-CoV-2. Antibody titers appear to markedly increase two weeks after infection, followed by a plateau. A more robust immune response is seen in patients with severe COVID-19 as opposed to mild or asymptomatic presentations. This trend persists with regard to the length of antibody maintenance. However, overall immunity appears to wane within two to three months post-infection.

Conclusion: Findings of this study indicate that immune responses to SARS-CoV-2 follow the general pattern of viral infection. Immunity generated through natural infection appears to be short, suggesting a need for long-term efforts to control the pandemic. Antibody testing will be essential to gauge the epidemic and inform decision-making on effective strategies for treatment and prevention. Further research is needed to illustrate immunoglobulin-specific roles and neutralizing antibody activity.