A study says immmunity through a single dose of vaccine after a Covid 19 infection is more potent

A study conducted by the Center For Arthritis and Rheumatism Excellence (CARE) in Kerala, the Kalinga Institute of Medical Research in Odisha, and the Amrita Institute of Medical Research in Kerala has found that immunity through a single dose of Covishied vaccine after a COVID-19 infection is more potent than immunity acquired by two shots of the vaccine or the infection alone.

The natural immunity of a Covid recovered person boosted with a dose of Covishied vaccine results in hybrid immunity. This guarantee long-lasting immunity in such persons, and more importantly, it could help India save more vaccine doses, Dr Padmanabha Shenoy, rheumatology and medical director, CARE Hospital, Kochi said.

The study headed by CARE is an ongoing process, where various aspects of the immune responses associated with COVID-19 are being analysed among 1,500 patients of the hospital.

The study found that the mean antibody titres (level of antibodies) in the group with hybrid immunity — natural immunity plus vaccine immunity from one dose — were at least 6-100 times higher than in the other three groups. It also showed that those with hybrid immunity had “the highest neutralisation potential of 83.37% as compared to 45.4% in the fully vaccinated group.” At 86.7%, the proportion of hybrid immunity patients, who had adequate neutralising antibodies — which defends cells from pathogens by neutralising them — was higher compared to other groups of patients.

“We had previously shown that patients with AIRD also form adequate humoral responses to COVID-19 infection equivalent to those in healthy controls (no co-morbidities). The current data shows that this can be augmented with a single dose of vaccine to produce a strong humoral (antibody-mediated) immune response. A major concern was whether a natural infection would produce specific neutralising antibodies. Hence, we tested in vitro the neutralising capacity of the sera of these patients and found that antibodies produced are those with neutralising capability,” said the study.

However, Dr Shenoy stressed that the purpose of the study was to introduce a vaccination policy change, and not to deter the vaccination drive. “If a person has vaccine-induced immunity, he/she has a certain level of immunity, which is good enough. In India, more than 60% of the population has been already infected. For such people, one dose of vaccine is enough,” he said.