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COVID-19 antibody response persists longer in patients with more severe symptoms

The strength and longevity of the antibody response to COVID-19 depend on the severity of the symptoms experienced by the patient, according to a recent study conducted by icddr,b researchers and partners.
 
The researchers conducted a longitudinal cohort study between November 2020 and August 2021 in Dhaka, Bangladesh and enrolled 100 adult patients with COVID-19 aged 18 and above. 
 
Disease severity of the patients was classified as asymptomatic, mild, moderate, and severe (25 per group) based on clinical symptoms and oxygen saturation (SpO2) according to WHO guidelines. 
 
The findings reveal that patients who had shown moderate to severe symptoms of COVID-19 retain high levels of anti SARS-CoV2 IgG antibodies up to at least six months after being infected. In comparison, mild and asymptomatic individuals show lower peak antibody levels, which drop further after three months of infection.
 
Importantly, patients who received a COVID-19 vaccine (Covishield, Moderna, Pfizer, or Sinopharm) one month after infection exhibited persistent antibody responses at six months after infection, regardless of the severity of symptoms, with higher peak antibody levels in the vaccinated individuals.
 
The researchers also investigated the dynamics of different immune cell populations, including memory B cells which can rapidly produce antibodies upon reinfection, and T helper cells, which had previously been observed to be associated with disease severity and outcomes from COVID-19. All patients produced memory B cells upon infection, which suggests the potential for at least some long-term immunity against reinfection, while symptomatic patients exhibited much stronger T helper cell responses.
 
The research article titled, “Longevity of memory B cells and antibodies, as well as the polarisation of effector memory helper T cells, are associated with disease severity in patients with COVID-19 in Bangladesh,” was published in the open access scientific journal Frontiers. The research was conducted by a group of scientists led by Marjahan Akhtar, Researcher, Infectious Diseases Division, icddr,b, Dhaka, Bangladesh.
 
“While asymptomatic patients do produce antibodies against COVID-19, the decreased magnitude and longevity relative to symptomatic individuals is concerning,” Dr Marjahan Akhtar noted. “Vaccination more consistently produces strong antibody responses and should be considered regardless of prior infection status. Understanding long-term immunity to COVID-19 will be key to designing effective vaccination and booster campaigns.”
 
Article Link: https://www.frontiersin.org/articles/10.3389/fimmu.2022.1052374/full

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