HYDERABAD: Heterologous booster shots have gained significance in light of the waning effect of vaccine doses, especially against different variants of the Covid-19 virus. Earlier, countries were administering homologous booster shots. However, a heterologous booster was cleared by several countries, including the US, UK, Israel, etc., for emergency use as it showed increased immunity levels and was more effective compared to homologous shots.
A study by Lancet on the effectiveness of heterologous and homologous boosters showed that the heterologous booster offers higher protection than the homologous booster. There is an increase in the immune response to the administration of heterologous booster shots on two counts – first cellular immunity and second, neutralizing antibodies.
Recently, the Indian government approved the emergency use of the COVID-19 vaccine CORBEVAX as a heterologous booster shot for all adults, making it the first such vaccine in India. Biological E’s CORBEVAX is safer and induces better neutralization antibodies against different variants of COVID-19 as a heterologous booster shot.
It can be administered as a booster shot six months after two doses of Covaxin or Covishield for all adults. Administering the CORBEVAX vaccine as a heterologous booster dose provides significant enhancement in immune response and excellent safety profile in people who have already taken two doses of either Covishield or Covaxin.
BE had undertaken a multi-centre Phase III placebo-controlled heterologous booster clinical trial among fully vaccinated 416 subjects aged 18 to 80 years. The CORBEVAX heterologous booster achieved a 5.5 to 6.7 fold (geometric mean fold rise) rise in neutralizing antibody titres. Subjects tested for neutralizing antibodies against Omicron also showcased a significant increase in antibody titres after receiving CORBEVAX as a heterologous booster shot. About 75 to 91% of these subjects showed neutralizing antibodies against Omicron Variant. The trial concluded that the CORBEVAX booster dose is safe and well tolerated, with no serious or grade 3 adverse events or adverse events of special interest during the three months of the follow-up period.
Dr. M. Raja Rao , Medical Superintendent of Gandhi Hospital, said that introducing heterologous booster shots was a step toward a much more scientific and time-sensitive vaccine policy
“Heterologous booster is a preferred choice for booster dose because it offers effectiveness against variants (Delta and Omicron), and improves cellular immune response (significant Th1 skew response),” he added.
