Protective Antibodies Persist for Months in Survivors of Serious COVID-19 Infections
In This Article
- Little is known about how long antibodies last in response to SARS-CoV-2 in the body
- Researchers found that measuring immunoglobulin (IgG) was highly accurate in identifying infected patients
- Massachusetts General Hospital researchers found that IgG levels remained elevated in COVID-19 patients for four months and were associated with the presence of protective neutralizing antibodies
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Since the initial spread of COVID-19, there has not been consensus on how long antibody responses to SARS-CoV-2 lasts. According to a new study led by researchers at Massachusetts General Hospital, patients who survive serious COVID-19 infections have long-lasting immune responses against the virus (up to four months in this study), offering hope that survivors can develop protection from reinfection.
Researchers obtained blood samples from 343 patients with COVID-19, most of whom had severe cases. The blood samples were taken up to four months after a patient's symptoms emerged. The blood's plasma was isolated and applied to laboratory plates coated with the receptor-binding domain (RBD) of the virus's spike protein, which attaches to cells, leading to infection. The team studied how different types of antibodies in the plasma bound to the RBD.
They found that measuring immunoglobin G (IgG) was highly accurate in identifying patients who had symptoms for at least 14 days and that IgG levels in these patients remained elevated for four months. Richelle Charles, MD, physician-investigator in the Division of Infectious Diseases at Mass General, said that this indicates that key antibody responses to COVID-19 do persist.
In another finding, Dr. Charles and colleagues showed that infected patients had immunoglobin A (IgA) and immunoglobin M (IgM) responses that declined to low levels within about two and half months or less on average. If a patient has IgA and IgM responses, they were likely infected with the virus within the last two months.
Jason B. Harris, MD, a pediatric infectious disease attending at MassGeneral Hospital for Children, said that knowing how long antibody responses last is essential before using antibody testing to track the spread of COVID-19.
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