New Delhi: A study published by ICMR and National Institute of Virology, Pune shows that people with both doses of Covishield vaccine have higher immunity against the Delta variant of the coronavirus.
It also said that COVID-19 recovered individuals who were administered Covishield had higher neutralizing responses against the Delta variant.
“The study demonstrated that the breakthrough cases and the COVID-19 recovered individuals with one or two doses of Covishield vaccine had relatively higher neutralizing responses against the Delta variant in comparison to the participants who were administered either one or two doses of Covishield,” it said.
A comparative assessment of Covishield vaccinated individuals were conducted and sera under this study were grouped into five categories: People who took one dose, those who were administered two doses, COVID-19 recovered people who got one dose, COVID-19 recovered individuals who received two doses and breakthrough COVID-19 cases.
An increase in NAb titers was observed for both B.1 and Delta variants in the sera of the participants who had completed two vaccine doses relative to one dose.
Neutralizing antibody titers against B.1 and Delta variants were highest among breakthrough participants which may be due to spike-specific T-cell responses.
A titer is a test that measures the presence and amount of antibodies in the blood.
The study found that significantly lower NAb titers were observed for the Delta relative to B.1 variant. However, NAbs in breakthrough participants and the COVID-19 recovered individuals with one or two-dose vaccination had relatively higher protection against Delta in comparison to the vaccines with one or two-dose vaccination.
Long-term follow-up of participants could help to understand the impact of natural infection and vaccination on long-term protection from SARS-CoV-2 offered by Covishield.
It is important to track the breakthrough infections for immune escape mutants, the report said.
