Why test for COVID-19 antibodies?
Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) is the viral strain that causes coronavirus disease 2019 (COVID-19).
Following infection, the immune system may generate antibodies to fight the infection. These are made at different times in different people and may take several days to appear, in rare cases (<5%) produce no antibodies. Detection of these antibodies indicates the person has been infected with COVID-19, but without testing there is no way to know.
With COVID-19, recent studies suggest that the protection provided by antibodies against the SARS-CoV-2 virus that causes it may decline rapidly following infection. A study in patients who had been hospitalised with COVID-19 found that weeks after infection, 10% of patients did not have detectable levels of antibodies. Another found that within 2-3 months, antibodies could not be detected in 40% of patients.
There is still debate that even if antibodies can be detected, whether or not they can prevent reinfection and, if so, what levels are required to provide that protection. Infection with a contagious disease doesn’t necessarily lead to complete protection against reinfection. As COVID-19 is a new infection this information is subject to change as research into the virus continues.
As the science develops so will our understanding of the virus. Currently regular repeat antibody testing enables a base-line to be established and to monitor changes over a period of time whether that is at an individual, workforce or general population level.