Coronavirus Immunity in COVID-19 Patients May Not Last More Than Two Months, Finds New Study

Initial results from an antibody testing study have revealed that COVID-19 antibodies remain stable in the blood of the majority of infected individuals almost two months after diagnosis and possibly longer.

However, the study, led by researchers and clinicians at St George’s, University of London (London, UK) in collaboration with colleagues from other institutions, did not detect antibodies in everyone exposed to the virus, thus opening discussions on how best to interpret antibody and viral tests. These findings answer questions on how long people can remain immune after exposure to COVID-19 and provide insights into how different age and ethnic groups respond to infection.

In the study, the researchers analyzed antibody test results from 177 individuals diagnosed with COVID-19 infection from a viral test and measured the levels of COVID-19 antibodies in their blood. The results showed that in patients with an antibody response, the levels remained stable for the duration of the study (almost two months). The study also showed that those patients with the most severe infections having the largest inflammatory response were more likely to develop antibodies. The researchers have attributed this to antibody responses working in parallel with an inflammatory response to severe disease, or that a higher viral load could lead to greater stimulation of the inflammatory and antibody development pathways.

Between 2 and 8.5% of patients did not develop COVID-19 antibodies at all which, according to the researchers, may be due to the fact that the immune response in these patients could be through other immune response mechanisms, such as different antigens or T-cells. Another reason could be that relatively mild infections may be restricted to particular locations in the body, such as within mucosal cells of the respiratory tract, where antibody responses are instead dominated by a secretory immune system. The study also found that being of non-white ethnicity was associated with a higher antibody response, just as older patients and those with other conditions, such as with hypertension and being overweight were also more likely to have an antibody response.

“Our results provide an improved understanding of how best to use viral and antibody tests for coronavirus, especially when not every person exposed to the virus will have a positive response. We need to understand how best to interpret the results from these tests to control the spread of the virus, as well as identifying those who may be immune to the disease,” said Professor Sanjeev Krishna, corresponding author on the paper from St George’s, University of London.

“With the number of infections in the UK going down, we now have the very welcome challenge of attempting to carry out more tests to understand whether other factors are associated with an immune response, such as viral load and genetic factors. We hope that by sharing our data at an early stage, this will accelerate progress towards effective use of test results around the world.”

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St George’s, University of London