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Study finds mixing vaccines ‘highly effective’ against Covid; experts call for ‘larger analysis’

Dr Ravi Shekhar Jha said that mixing of vaccines is not recommended as "every vaccine is made differently and may react differently for different people".

By: Lifestyle Desk | New Delhi |
October 19, 2021 6:20:46 pm
vaccinesEven though Covid-19 vaccines have been developed in a short time and are being given EUA, we haven't cut short the trial and have a good amount of safety data from their phase-2 and phase-3 trials. (File)

A new Lancet study has said that mixing Covid-19 vaccines can be ‘highly effective’, leading to ‘lower risk of infection’. Published in The Lancet Regional Health – Europe journal, the study noted that since the use of AstraZeneca’s vector-based vaccine was halted for people younger than 65 years of age due to safety concerns, people in Sweden who had already received their first dose were recommended an mRNA vaccine as their second dose.

“Our study shows a greater risk reduction for people who received an mRNA vaccine after having received a first dose of a vector-based, as compared to people having received the vector-based vaccine for both doses,” said Peter Nordstrom, a professor at Umea University, Sweden said, reported PTI.

The study, that included seven lakh individuals, also noted that during a 2.5-month average follow-up period after the second dose, the study showed a 67 per cent lower risk of infection for the combination of AstraZeneca and Pfizer vaccine shots. However, for people who received two doses of the AstraZeneca vaccine, known as Covishield in India, the risk reduction was 50, the authors said stating that it was valid to even the Delta variant.

Is it safe and better?

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Stating that the mix of vaccines started in Europe due to “due to non-availability or shortage of vaccines”, Dr Manoj Sharma Senior Consultant Internal Medicine Fortis Hospital Vasant Kunj, New Delhi, said “there is not enough data anywhere in the world to decide if this is a good idea”. “We don’t have any compelling reason to mix or match as we don’t have shortage. We also don’t have enough data to comment about it and how it will fare in the long run,” he told

In a video podcast dated September 17, 2021, Dr Katherine O’Brien from World Health Organization spoke about the efficacy of a few clinical trials combining with a first dose, either AstraZeneca or an mRNA vaccine and then the second dose, with switching over to the other product. “What we know about the safety is that the amount of reaction in your arm and some of the general short-term reactions that people get, not feeling well or a low grade fever are generally speaking the same, whether you mix and match or whether you use the same regimen. So we do have safety evidence on this,” she said.

Dr Ravi Shekhar Jha, additional director and head of department pulmonology, Fortis Escorts Hospital, Faridabad said that mixing of vaccines is not recommended as “every vaccine is made differently and may react differently for different people”. This is just one such study, the scope needs a larger analysis, he opined.

A small Indian Council of Medical Research study also found that vaccine mixing is safe, and offers better immunity. The researchers of the study among 18 participants, found that a combination of Covishield and Covaxin shots is safe and, in fact, offers better immunogenicity than two doses of the same vaccine. However, they made it clear that the evidence is very limited and called for multi-centre randomised clinical trials to conclusively prove the findings. The study has been accepted for publication in the International Journal of Travel Medicine.


However, Dr Shuchin Bajaj, founder director, Ujala Cygnus Group of Hospitals believes it is a “good development” nonetheless. “It is giving us hope that we can also work on some other diseases based on this module of mixing the vaccine technologies because mostly till now we have only one kind of vaccine for diseases. Usually we do not develop another kind of vaccine when one vaccine is working well for a disease,” he said.

He further described that one of the first principles of the branches of medicine is giving two medicines rather a maximum dose of one. “For instance, if you have high blood pressure, we prefer to add one more medicine to the first medicine if the blood pressure is not controlled, instead of increasing the first medicine dose to the maximum. This ensures that the side effects are lower because the lower the dose, the lesser is the side-effect,” he added.

Also, if WHO is to go by, more evidence needs to be generated.


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📣 The above article is for information purposes only and is not intended to be a substitute for professional medical advice. Always seek the guidance of your doctor or other qualified health professional for any questions you may have regarding your health or a medical condition.

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First published on: 19-10-2021 at 06:20:46 pm

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