Infection by SARS-CoV-2 triggers the creation of antibodies in a two-part response: 
- early antibodies (IgM)
- late antibodies (IgG)

With assistance from helper T cells, B cells differentiate into plasma B cells to produce these antibodies against the SARS-CoV-2 antigens.

Antibodies and COVID-19 

- Response occurs ~1 week after onset of symptoms
- Some may not develop long-lasting antibodies to the virus
- Convalescent plasma treatment is a viable option
- The majority of antibodies to SARS-CoV-1 do not bind to the SARS-CoV-2 virus, likely due to differences in the receptor-binding-domain

University of California, Davis

Michigan State University

Smith College

A review study presented on the pathophysiology of the COVID-19 virus and found that entry and replication by the virus into cells expressing ACE 2 receptors triggers host cell pyroptosis, generating pro-inflammatory cytokines and chemokines which recruit monocytes, macrophages, and T-cells. This results in further inflammation and creation of a pro-inflammatory feedback loop, leading to overproduction of cytokines that accumulate in the lungs, causing a cytokine storm.

Review Investigating the Immunopathogenesis of COVID-19

- B-Cell Immunity in COVID-19
- T-Cell Immunity in COVID-19
Adaptive response process
- Blood brings the cells throughout the body as normal where the B cells are working alongside t cells to go into the plasma where they produce antibodies specific to the antigen.  
- A neutralizing antibody is efficient in fully blocking the virus from entering the host cells. This helps limit the infection and relapse. 
- The overall adaptive immune response is directed by helper T cells, and cytotoxic T cells play a vital role in the clearance and cleaning of viral-infected cells
- Adaptive immune response against coronavirus requires stimulation of B cell and T cell epitopes


Adaptive Immune Response to COVID-19

Tay, M. Z., Poh, C. M., Rénia, L., Macary, P. A., &amp; Ng, L. F. (2020). The trinity of COVID-19: Immunity, inflammation and intervention. Nature Reviews Immunology, 20(6), 363-374. doi:10.1038/s41577-020-0311-8
https://www.nature.com/articles/s41577-020-0311-8

The trinity of COVID-19: immunity, inflammation and intervention

Figure: Chronology of events during SARS-CoV-2 infection.

B-Cell Immunity in COVID-19

- CD8+ T-cells: Directly attacks and kills virus-infected cells
- CD4+ T-cells: Primes CD8+ T cells and antibody-producing B cells, responsible for cytokine production
- T-cell exhaustion and reduced functional diversity lead to severe disease

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