Mixing COVID-19 vaccination shots: Too much, too soon, doctors say  

However, there is very little research on whether an individual can be given one dose each of two different vaccines where a two-dose regimen is involved.

Published: 05th April 2021 05:50 AM  |   Last Updated: 05th April 2021 10:37 AM   |  A+A-

Covishield and Covaxin

Covishield and Covaxin

Express News Service

BENGALURU: As cases across India rise worryingly, there is curiosity about whether or not an individual can be given one dose each of two different vaccines.

If it were possible, it could speed up the vaccination process, help overcome supply bottlenecks, and to some extent reduce wastage of doses, health professionals say.

However, there is very little research on whether an individual can be given one dose each of two different vaccines where a two-dose regimen is involved.

Currently, India has given emergency-use approvals for the use of Covishield and Covaxin, both of which have two-dose regimen.

While Covishield, developed by Oxford University, uses adenovirus (which causes cold in chimpanzees), Covaxin uses a dead virus to induce immunity. 

“While there have been several people who wondered if the two vaccines that are available in India — Covishield and Covaxin can be taken (in combination). The answer is no for now,” said Dr V Ravi, renowned virologist and nodal officer for INSACOG lab at Nimhans.According to him, no scientific data available till now, although attempts are on to study this.

The United Kingdom’s National Health Service is currently looking for participants for a study on the effects on the immune system when an individual is primed with one particular vaccine (the first shot) and is boosted with another (second shot), he said.

Called Com-COV, the study involves researching the effectiveness of the vaccines developed by Oxford University and Pfizer when they are combined. Neither of the vaccines uses SARS-CoV-2, and so, one cannot contract Covid-19 from the vaccines.

“The data could be interesting. The concept of mixing vaccines, which is also called heterologous prime boost, is not new to pandemics. For many years this has been investigated, with the hope that potent combinations against a range of viruses such as influenza, HIV and Ebola can be found,” said a senior virologist from Manipal.

According to Dr Ravi, who is a member of the international scientific advisory board for Sputnik V, a study on the Russian vaccine is under way.

Gamaleya Institute, manufacturer of Sputnik V, has partnered with pharmaceutical company AstraZeneca. They have registered a pair of clinical trials in which volunteers will receive one dose each of Oxford University’s vaccine and Sputnik V.

However, this is under review. 

Interestingly, an expert panel has permitted Hyderabad-based vaccine maker Bharat Biotech to administer a third dose of Covaxin to some of volunteers in its ongoing clinical trials.

The approval, a result of the Hyderabad-based vaccine maker’s proposal to use an additional booster dose, would allow it to test the ability of Covaxin to prompt an immune response that could last a few years.


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