PremiumNew Delhi: Immunization with a combination of first dose of Covishield followed by second dose of Covaxin is not only safe but also elicits better immunogenicity, the Indian Council of Medical Research (ICMR) said on Sunday, citing its preprint research. When peer reviewed and recognized, the research may pave the way for more flexibility in mixing and matching covid-19 vaccines in India.
Immunization programme against covid-19 in India started with two vaccines Covishield and Covaxin on January 16. While Covishield is the in-country version of Oxford-AstraZeneca vaccine manufactured by Serum Institute of India (SII), Covaxin is an inactivated whole virus vaccine (BBV152) developed jointly by ICMR -National Institute of Virology (ICMR-NIV) and Bharat Biotech International Ltd.
The regime for both the vaccines initially included a second homologous booster dose following a priming dose at an interval of four weeks. With gradually emerging evidence, the gap between the two doses of Covishield was increased to 6-8 weeks and later to 12 weeks.
A group of individuals in Uttar Pradesh received Covishield as the first dose followed by inadvertent administration of Covaxin as the second dose at an interval of six weeks.
“We compared the safety and immunogenicity profile of them against that of individuals receiving either Covishield or Covaxin (40 in each group). Lower and similar adverse events following immunization in all three groups underlined the safety of the combination vaccine-regime," said the authors.
“Immunogenicity profile against Alpha, Beta, and Delta variants in heterologous group was superior; IgG antibody and neutralising antibody response of the participants was also significantly higher compared to that in the homologous groups," ICMR said in the study.
The apex biomedical research organization further maintained that the findings suggest that immunization 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.
“Overall, this study demonstrates that immunization with a heterologous combination of an adenovirus vector platform-based vaccine followed by an inactivated whole virus vaccine is safe and elicits better immunogenicity than two doses of homologous vaccination, using the same vaccines," the study said.
These findings have an important implication for the covid-19 vaccination programme wherein heterologous immunization will pave the way for induction of improved and better protection against the variant strains of SARS-CoV-2. Such mixed regimens will also help to overcome the challenges of shortfall of particular vaccines and remove hesitancy around vaccines in people’s mind that could have genesis in programmatic ‘errors’ especially in settings where multiple covid-19 vaccines are being used, the ICMR said.
There has been rising evidence of better safety profiles of mixing and matching of covid-19 vaccines. India's covid-19 working group of the National Technical Advisory Group on Immunisation (NTAGI) is also considering to allow mix and match Covishield and Sputnik V vaccines against covid-19, along with mixing of similar platform vaccines to be available in the country in due course.
According to officials in the Union health ministry, an expert panel of India’s Central Drugs Standard Control Organization (CDSCO) last week recommended granting permission to the Christian Medical College (CMC) in Vellore for conducting a clinical trial of mixing of two covid-19 vaccines—Covaxin and Covishield.
The officials reportedly said the subject expert committee (SEC) after detailed deliberations recommended granting permission to CMC for conducting the phase-4 clinical trial covering 300 healthy volunteers for mixing of covid-19 vaccines Covaxin and Covishield. The aim of the study is to assess whether a person can be given two different vaccine shots—one each of Covishield and Covaxin—to complete the inoculation course, panel said.
However, with more and more clinical trials being done in mixing and matching of covid-19 vaccines, Soumya Swaminathan, chief scientist at World Health Organization (WHO) earlier in July termed mixing and matching Covid-19 vaccines from different manufacturers as "dangerous trend" due to little data available.
"It's a little bit of a dangerous trend here. We're in a data-free, evidence-free zone here as far as mix-and-match. There is limited data on mix-and-match. It will be a chaotic situation in countries if citizens start deciding when and who will be taking a second, a third and a fourth dose," Soumya Swaminathan had said during an online briefing in Geneva.
While India’s cumulative covid-19 vaccination coverage neared 520 million, India reported 39,070 new coronavirus cases in the last 24 hours with 616 deaths. India's active caseload is currently 406,822, making 1.27% of total cases, the health ministry data shows.
With an expansion of India’s covid-19 vaccine basket, global healthcare major Johnson and Johnson has received Emergency Use Authorization (EUA) for its single-dose covid-19 vaccine Janssen in the country. India mainly has three covid-19 vaccines available for administration currently—Covaxin, Covishield, and Russia’s Sputnik V, while Moderna vaccine (mRNA-1273) also has received EUA in India recently.
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