Immunity to a pathogen through natural infection is a multi-step process that usually takes place over 1-2 weeks. The body responds to a viral infection immediately with a non-specific innate response: macrophages, neutrophils, dendritic cells slow the progress of the virus.
This non-specific response is followed by an adaptive response i.e. body makes #antibodies that specifically bind to the #virus. These #antibodies are proteins called #immunoglobulins. The body also makes T-cells that recognize & eliminate other cells infected with the virus.
This MAY clear the #virus from the body; if response is strong enough, it MAY prevent progression to severe illness / re-infection by the SAME #virus. This is often measured by the presence of #antibodies in blood. Evidence on antibody responses to #SARSCoV2 infection is growing.
Most studies show that people who have recovered from infection have #SARSCoV2 #antibodies. However, some have VERY LOW levels of neutralizing antibodies in the blood suggesting that cellular immunity may also be critical for #COVID19 recovery.
Laboratory tests that detect antibodies to #SARSCoV2 in people, including rapid immunodiagnostic tests, need further validation to determine their ACCURACY and RELIABILITY. Inaccurate immunodiagnostic tests may FALSELY categorize people in two ways.
Tests may 1) falsely label people who have been infected as negative or 2) falsely label people who haven't been infected as positive. Both have serious consequences. Tests also need to distinguish between past #SARSCoV2 infections from #infection with other human #coronaviruses.
