A recent study by the Indian Council of Medical Research (ICMR) stated that combining doses of Covidshield and Covaxin can give better immunogenicity than two doses of the same vaccine. ICMR conducted this study on 98 people, of which 18 had received Covishield as the first dose and Covaxin as the second in Uttar Pradesh. These 18 individuals in Siddarthnagar, Uttar Pradesh inadvertently received Covishield as the first jab and Covaxin as the second.
The study titled ‘Serendipitous Covid-19 Vaccine-Mix in Uttar Pradesh, India: Safety and Immunogenicity Assessment of a Heterologous Regime’ reported that the immunisation with the mixing of Covidshield and Covaxin was safe. The adverse effects were found to be similar when compared to the same dose regimen. The study has been uploaded on medRxiv, a preprint server, and is yet to be peer-reviewed.
“To the best of our knowledge, this is the first study which reports the effects of heterologous prime-boost vaccination with an adenovirus vectored vaccine followed by an inactivated whole virus vaccine,” the researchers said.
Both adenovirus vector platform-based vaccine Covishield and inactivated whole virion BBV152 -Covaxin- are the main vaccines in India’s vaccination drive. There is a lot of vaccine hesitancy among the public as well as a dearth of studies to prove that the mixed dosing is safe and can yield effective results. Hence, the study was conducted against this backdrop.
The safety and immunogenicity profile of the 18 individuals against that of those receiving either Covishield or Covaxin was compared. Lower and similar adverse events following immunisation in all three groups underlined the safety of the combination vaccine regime.
“Immunogenicity profile against Alpha, Beta and Delta variants in the heterologous group was superior and IgG antibody and neutralising antibody response of the participants was also significantly higher compared to that in the homologous groups,” the study stated.
A combination of an adenovirus vector platform-based vaccine followed by an inactivated whole virus vaccine was not only safe but also elicited better immunogenicity, the study inferred.