The researchers not only discovered a possible protective effect against re-infection with COVID-19, but also found that the measurement of antibodies can be an accurate tool to monitor the spread of the virus in society.
Surviving a severe COVID-19 infection could provide long-term protection from re-infection for affected individuals, according to a new study led by researchers at Massachusetts General Hospital (MGH). The study was published in the English language journal “Science Immunology”.
When people survive a severe COVID-19 infection, they appear to have a long-lasting immune response against the virus. This raises the hope that people who are infected with the virus will develop long-term protection against re-infection.
Gaps in knowledge regarding antibody reactions
Does COVID-19 provide protection against a new infection?
It is known that the immune system produces special proteins called antibodies in response to the SARS-CoV-2 virus that causes COVID-19. However, the researchers report that there is still a large knowledge gap regarding the duration of these antibody reactions.
The research group therefore took blood samples from 343 people with COVID-19, most of whom had severe cases of the disease. The blood samples were collected up to four months after the onset of symptoms. The blood plasma was isolated and applied to laboratory plates coated with the receptor binding domain (RBD) of the virus’ spike protein, which attaches to cells and causes infection.
Traceable spread of the virus
The team investigated how different types of antibodies bind to RBD in plasma. The results were then compared to blood samples taken from more than 1,500 people before the pandemic.
The research group found that the measurement of an antibody called immunoglobulin G (IgG) was very accurate in identifying infected individuals when they showed symptoms for at least 14 days.
“This means that people are very likely to be protected for this period,” study author Dr. Richelle Charles of Massachusetts General Hospital explained in a press release.
The team also found that IgG levels remained elevated for four months and were associated with the presence of protective neutralizing antibodies, which also showed a slight decrease in activity over time.
“We can now say that if a patient had IgA and IgM responses, he was probably infected with the virus within the last two months,” concludes Dr. Charles. The findings on the duration of the immune response by IgA and IgM will also help to obtain more accurate data on the spread of SARS-CoV-2, the study author added.
In another finding, the team showed that people infected with SARS-CoV-2 had immunoglobulin A (IgA) and immunoglobulin M (IgM) responses that were relatively short-lived and decreased on average to low levels within two and a half months or less.
WashingtonNewsday Health and Wellness.