Covishield, Covaxin Combination Brings Better Immunogenicity Than Two Doses Of Same Vaccine: ICMR Study

This study by the Indian Council of Medical Research (ICMR) showed that combining these two Covid-19 vaccines elicited better immunogenicity than two doses of the same vaccine.

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New Delhi: The recipients, who received a mix of Covishield and Covaxin doses, got better immunogenicity than two doses of the same vaccine, according to a study.

This study by the Indian Council of Medical Research (ICMR) showed that combining these two Covid-19 vaccines elicited better immunogenicity than two doses of the same vaccine.

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The study also found that immunisation with combination of Covishield and Covaxin was safe and the adverse effects were also found to be similar when compared to the same dose regimen.

“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,” PTI quoted the researchers as saying.

The duration of the study involving 98 people, 18 of whom had inadvertently received Covishield as first dose and Covaxin as the second in Uttar Pradesh, was from May to June 2021.

18 individuals, under the national program, in Siddarthnagar, Uttar Pradesh, inadvertently received Covishield as the first jab and Covaxin as the second.

So, including these 18 individuals who had received one dose of Covishield and second dose of Covaxin, 40 recipients of two doses of Covishield and 40 recipients of two doses of Covaxin, were recruited in the study.

 “We compared the safety and immunogenicity profile of them (18 individuals) against that of those receiving either Covishield or Covaxin. Lower and similar adverse events following immunisation in all three groups underlined the safety of the combination vaccine-regime,” the study stated, adding "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 titled ‘Serendipitous Covid-19 Vaccine-Mix in Uttar Pradesh, India: Safety and Immunogenicity Assessment of a Heterologous Regime’ has been uploaded on medRxiv - a preprint server - and is yet to be peer reviewed.

The findings, according to the study, suggest that immunisation with 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 reactogenicity analysis was carried out based on solicited local and systemic Adverse Events Following Immunization (AEFI) reported in the three groups within seven days of immunisation.

None of the participants had any serious AEFI within 30 minutes of immunisation with the first or second dose. The most common local AEFI reported after the first and second dose was pain at injection site.

No other local AEFI such as erythema, induration, pruritis or pustule formation was, however, recorded by any of the participants. Most commonly reported systemic AEFI were pyrexia and malaise.

No other systemic AEFIs like urticaria, nausea, vomiting, arthralgia or cough was reported.

“Despite the high median age of the participants of the heterologous group (62 years) in our study, the reactogenicity profile demonstrated that mixing of the two vaccines based on different platforms is safe,” the study said.

These findings have an important implication for the Covid-19 vaccination program wherein heterologous immunisation will pave way for induction of improved and better protection against the variant strains of SARS-CoV-2.

The study also highlighted that such mixed regimens would help in overcoming the challenges of shortfall of particular vaccines and remove hesitancy around vaccines in the minds of the people.

The study, however, underscored that a multicentre Randomized Controlled Trial (RCT) needs to be carried out to conclusively prove these findings.