All India Institute of Medical Sciences (AIIMS) Director Dr. Randeep Guleria said on July 1 that more data would be required on mixing of COVID-19 vaccine doses before the practice is tried.
“More data is needed on mixing of doses. Studies show that it may be effective and little more side effects may be there. But we need more data before we can say that this is a policy that should be tried,” news agency ANI quoted Guleria as saying.
A recent study in the United Kingdom had found that alternating doses of the Oxford University-AstraZeneca and Pfizer-BioNTech vaccines generate robust immune responses against the novel coronavirus' spike IgG protein.
The study showed that both the mixed schedules of the AstraZeneca and Pfizer jabs, when given at a four-week interval, induced an immune response that is above that of the AstraZeneca vaccine.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Experts had told Moneycontrol earlier that the data from such trials is encouraging, but also called for more such studies to find out which combination works the best and with least side-effects.Read: What five experts are saying on 'mix and match' of COVID-19 vaccines
Mixing of COVID-19 vaccines is currently not allowed in India. Covishield, the jab developed by Oxford University-AstraZeneca and produced in the country by the Serum Institute of India (SII), and Bharat Biotech’s Covaxin are the two main vaccines currently being used on a large scale in India. Sputnik V, the Russian vaccine, is also being imported by Dr. Reddy's Laboratories and used for inoculations in limited quantities in the country.Follow Moneycontrol’s full coverage of the coronavirus pandemic here