New Delhi: The Indian Council of Medical Research (ICMR) has revealed in its study that the combination of Covaxin and Covishield vaccines, the two main vaccines of the COVID-19 vaccination programme, conducted on 18 people, has elicited better safety and immunogenicity results. According to the study, immunization with a combination of an adenovirus vector platform-based vaccine followed by inactivated whole virus vaccine was not only safe but also elicited better immunogenicity.
In the study, ICMR compared the safety and immunogenicity profile with those individuals who received either Covaxin or Covishield and it showed better results. The study conducted on individuals in the northern state of Uttar Pradesh in India received Covishield as the first dose followed by inadvertent administration of Covaxin as the second dose at an interval of six weeks.
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As per Dr Samiran Panda, Head of Epidemiology and Communicable Diseases, ICMR, "it was like a natural experiment when second time these individuals inoculated with different doses inadvertently." He informed that ICMR decided to conduct the study so that people would not get anxiety or vaccine hesitancy. "We went to the place and collected samples of individuals," said Dr Panda. A total of 18 participants were in the heterologous group. However, two participants were unwilling and were excluded. Among them, 11 were male, and seven were female with a median age of 62 years.
"A comorbid condition (hypertension) was reported in one (5.5 per cent) individual. In both the homologous groups, 40 individuals were included," the study said. "We compared the safety and immunogenicity profile of them against that of individuals receiving either Covishield or Covaxin (n=40 in each group). Lower and similar adverse events following immunization in all three groups underlined the safety of the combination vaccine regime. The immunogenicity profile against Alpha, Beta, and Delta variants in the heterologous group was superior; IgG antibody and neutralising antibody response of the participants was also significantly higher compared to that in the homologous groups," the study said.
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Earlier, a UK study had found that a mix-and-match approach to COVID-19 vaccines - using different brands of jab for first and second doses - gives good protection against the virus. The Com-Cov trial looked at the efficacy of either two doses of Pfizer, two of AstraZeneca, or one of them followed by the other. All combinations worked well, priming the immune system.
The Com-Cov study, which looked at giving the doses four weeks apart in 850 volunteers aged 50 and above, found that an AstraZeneca jab followed by Pfizer induced higher antibodies and T cell responses than Pfizer followed by AstraZeneca. Both of these mixes induced higher antibodies than two doses of AstraZeneca, the report said. The highest antibody response was seen after two doses of Pfizer, and the highest T cell response from AstraZeneca followed by Pfizer, it said.
(agency inputs)
