Once infected, the body's immune system is expected to produce antibodies against SARS-CoV-2. These antibodies serve as the targets for immunoassay-based diagnostic kits. However, after recovery from the COVID-19, it is expected that these antibodies may still be found in the blood. For how long do they remain in the blood?
If they remain for so long in the blood of a person who recovered from COVID-19, what are the chances of such person testing positive again (if immunoassay-based testing is conducted)?
How long the antibodies to SARS-COV-2 after recovery from COVID-19 last?
According to the evidence available so far, the COVID-19 patients who have recovered may never develop antibodies, and those who develop these antibodies may not necessarily be immune (1).
The duration of SARS-CoV-2 antibodies in the studies so far have been 8 weeks (2). Longitudinal studies following COVID-19 recovered patients for a longer duration will shed further light on the minimum and maximum duration of antibodies in such patients.
HOWEVER, WHETHER THESE ANTIBODIES ARE PROTECTIVE FROM ANOTHER SARS-COV-2 INFECTION IS A BIG QUESTION MARK! (3)
1. Preprint Prevalence of IgG antibodies to SARS-CoV-2 in Wuhan - implic...
2. Preprint Evaluation of antibody testing for SARS-Cov-2 using ELISA an...
3. Article The potential danger of suboptimal antibody responses in COVID-19
Pan, Yunbao, Xinran Li, Gui Yang, Junli Fan, Yueting Tang, Jin Zhao, Xinghua Long et al. "Serological immunochromatographic approach in diagnosis with SARS-CoV-2 infected COVID-19 patients." Journal of Infection (2020).
The development of immunity to a pathogen through natural infection is a multi-step process that typically takes place over 1-2 weeks. The body responds to a viral infection immediately with a non-specific innate response in which macrophages, neutrophils, and dendritic cells slow the progress of virus and may even prevent it from causing symptoms. This non-specific response is followed by an adaptive response where the body makes antibodies that specifically bind to the virus. These antibodies are proteins called immunoglobulins. The body also makes T-cells that recognize and eliminate other cells infected with the virus. This is called cellular immunity. This combined adaptive response may clear the virus from the body, and if the response is strong enough, may prevent progression to severe illness or re-infection by the same virus. This process is often measured by the presence of antibodies in blood.