Commenting on the ICMR study, the Chairman of Covid Shield maker Serum Institute of India, Cyrus Poonwalla says, mixing two different vaccines is a very risky decision and must be discouraged.
He further said, “I am against the mixing of vaccines. If mixing is done and results are not good then vaccine manufacturers will blame each other for results. First of all, the vaccine authority will never give full approval because it is a very risky decision and it is a waste of time. When one vaccine is working why should we mix it up and cause complications? We should completely discourage this”
As per the study of 98 people by the ICMR, where 18 people received Covid Shield as the first dose and Covaxin as the second dose in Uttar Pradesh’s Siddhart Nagar, it was found that immunization with a cocktail of Covidshield and Covaxin was safe and the adverse effects were also found to be similar when compared to the same dose regimen.
The study says, “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.
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”.
What does the World Health Organisation say?
According to the World Health Organisation, currently, there is limited data on the immunogenicity or efficacy of a “mix and match” regimen. The AstraZeneca recommendations have been modified to indicate that either of the mRNA vaccines (Pfizer or Moderna) can be used as a second dose following a first dose of the AstraZeneca vaccine if the second dose of AstraZeneca is not available. Based on the basic principles on which vaccines work, WHO is of the view that mix and match regimens are likely to work. Though, we really need to analyse the evidence in each of these vaccine combinations before any other recommendations can be made.