According to a study published in journal Cell, the strongest T cell responses were present in individuals who recovered from severe Covid-19 infection, while even mild cases of Covid-19 lead to robust memory T cell responses to SARS-CoV-2. The memory T cell is one of the key components that helps in preventing recurrent episodes of the virus.
Senior author of the study, Marcus Buggert of the Karolinska Institutet in Sweden, stated: “It is critical to determine if exposed or infected people, especially those with asymptomatic or very mild forms of the disease who likely act inadvertently as the major transmitters, develop robust adaptive immune responses against SARS-CoV-2.”
Most studies on the protection of the body from Covid-19 are focused on generating neutralising antibodies.
But the researchers in their study noted that the effect of the antibodies tends to wane over a period of time. Moreover, they are not detectable in all patients, particularly those with mild symptoms of Covid-19.
For their research, the team examined Covid-19 virus-specific T cell and antibody responses in more than 200 individuals from Sweden across the full spectrum of exposure, infection and disease.
In line with expectations, all 23 individuals who recovered from severe Covid-19 developed both SARS-CoV-2 specific antibody and T cell responses.
“Our findings suggest that the reliance on antibody responses may underestimate the extent of population-level immunity against SARS-CoV-2,” Buggert maintained.
“The obvious next step is to determine whether robust memory T cell responses in the absence of detectable antibodies can protect against Covid-19 in the long term,” the authors said.