With the government announcing nearly 12 crore doses up for takes in the coming months, India is still running short on COVID vaccine. A research study on mixing COVID-19 doses and finding out its effectiveness in boosting the immune response to Coronavirus is being taken up to address shortfalls in single brands. The central government has set up a panel of scientists who will conduct experiments using the vaccines already available in the market and those in the pipeline, as reported.

At present, there are six COVID vaccines in the pipeline. Serum’s Covax, Zyndus Vadila’s ZyCov-D, Biological E’s Corbevax, Bio E’s version of Johnson and Johnson Covid vaccine, Genova’s mRNA vaccine and Bharat Biotech’s intranasal Covid-19 vaccine. Pfizer is also in talks with the government to bring it to the Indian market this year.

The mixing of vaccines for COVID-19 has earlier been discussed at the COVID-19 group, NTAGI and National Expert group on COVID-19 Vaccine Administration (NEGVAC).

Regarding the study on mixing COVID-19 doses, Dr Arora said, "We have heard recently that Europe, Spain and United Kingdom are also doing a study where two vaccines - Covishield and Pfizer, have been given on alternate days. Covishield as the first dose and the second dose of Pfizer or vice versa. This is called interchangeability studies".

"Two vaccines may be given in different orders for three purposes. One is that these become convenient programmatically, but more important is that it shouldn't create any safety issues and the third is to ascertain if there is an immune advantage, whether the effectiveness of this mix and matching increases the protective efficacy of the vaccines. So, all these three things have to be taken care of simultaneously," he explained further.

A study published in medical journal, The Lancet, had showed that people who were given the AstraZeneca vaccine as the first dose and Pfizer’s as the second reported more short-lived side effects. The study, however, did not say if the mixing of vaccines could help protect against the infection.

Another study in Spain found that the two vaccines given in the same order was highly effective. One of the scientists said that 1.7% of participants reported severe side effects such as headaches and muscle pain.

Studies on mixing of vaccines and the after effects - both positive and negative will go a long way in planning the immunisation programs both in the short and long run.