In the first phase of the COVID-19 pandemic , antibody testing was proposed by several countries as a means of gathering data on the spread of the virus and/or , to inform strategies to ease restrictive measures , and test and trace programmes ( Baraniuk 2020 ) particularly to identify the source of clusters of infections ( Normile 2020 ) . In the UK , the Prime Minister said antibody testing was a potential ' game - changer ' ( BBC 2020 ) . The presence of antibodies indicates an individual 's immune system has responded to the virus . Antibody tests differ from antigen tests that determine whether someone is currently infected . In the case of this virus , at the time this study was conducted in April / May 2020 , scientists and the public had little understanding of the longevity of antibodies , and whether they provided immunity to reinfection or transmission . The current ( January 2021 ) knowledge is that antibodies are maintained for at least eight months ( Dan 2021 ) and for at least three months in those who had mild COVID-19 symptoms ( Rodda 2020 ) . There is evidence that people can be re - infected ( Parry 2020;Hall 2021 ) and work continues to gain a greater understanding of antibodies and immunity . Interim findings from a large cohort study of COVID-19 antibody - positive and antibody - negative UK health workers found antibodies , produced in response to a previous infection , provided 83 % protection against reinfection for five months ( Hall 2021 ) . Although the findings have been welcomed , the sample consists primarily of women under the age of 60 and it is too early to determine immunity against the new variants of the virus ( Ledford 2021 ) . The cohort study will follow participants for 12 months to provide further data on how long immunity lasts and the degree to which someone with immunity can transmit the virus to others ( Hall 2021 ) .