Express press service
BENGALURU: Antibody levels and duration of immunity vary in people recovering from Covid-19, finds a study published in The Lancet. Entitled “Dynamics of SARS-CoV-2 Neutralizing Antibody Responses and Duration of Immunity: A Longitudinal Study,” published March 23, the study monitored neutralizing antibodies in patients up to six months after onset. symptoms.
Dr Ravindra Mehta, senior consultant and head of respiratory and interventional pulmonology at Apollo Specialty Hospitals, said that in some people, antibody levels dropped quickly, but lasted longer in others. In some patients the levels fluctuated and in others the antibodies were present for up to six months. “The persistence of neutralizing antibodies was associated with the severity of the disease and the sustained level of pro-inflammatory cytokines, chemokines and growth factor,” the study said.
That means those who had a severe infection, along with inflammation caused by cytokine storms, were found to have antibodies for up to six months, Dr Mehta said. “In people who had a milder infection or who were asymptomatic, the antibody levels were low. However, T cell immunity, which is long-term cellular immunity, was present in people despite the disappearance of neutralizing antibodies, ”he said.
The rate of decline in antibody levels suggests that reinfection is likely in subsequent waves, limiting the viability of a herd immunity strategy before an effective vaccine, according to the study. “Collective immunity depends on the availability of antibodies in a community, but antibodies decline over time. If the infection is rapid, the T cells are often not able to remember the antibody response because the B cells, which are the neutralizing antibodies, take over to fight the current infection, ”said Dr. Sheela Chakravarthy, Director of Internal Medicine at Fortis Hospitals. .
“Since we don’t know the response of memory T cells, it’s best to get vaccinated. They will produce neutralizing antibodies and booster doses can be given, ”she said. The study found that patients with persistent antibodies were older and had more comorbidities, including hypertension.