Mixing Covishield And Covaxin – Does It Work Better?

UPDATE: As of the beginning of 2022, an additional study was carried out by AIG Hospitals in Hyderabad that confirmed the information below. A mix of Covaxin and Covishield vaccines was shown to leave the body with more virus-fighting antibodies than simply getting two doses of the same vaccine. The test was conducted by using Covaxin first and Covishield second as well as the converse of the same. In both cases, this mixed vaccine regime showed a much higher antibody response (up to 4 times more) than two doses of the same vaccine. Also, one of the hopeful results from this study states that mixing these vaccines is safe for humans. Read on to learn more:

Introduction

Earlier, Covaxin was said to be better at protecting the new Delta variant of the SARS CoV2 virus. These claims were made by Bharat Biotech for their inactivated virus type vaccine but there wasn’t enough review available on these claims.

Although it may come across as a bit unorthodox, there have been ideas floating around for a while now regarding mixing vaccines for better potency. At the forefront of this idea were the first two vaccines being given out on a massive scale in India, Covaxin and Covishield. The latest results from ICMR shows that mixing these two does in fact produce better results.

The immune response to COVID-19 vaccines may wane over time. Booster shots are a safe and effective way to extend protection against variants of concern.

Dr. Ashish Bajaj, M.B.B.S., M.D. in Clinical Pharmacology and Toxicology

How Does Covishield And Covaxin Work By Themselves

Fundamentally, Covishield and Covaxin work in different ways. Covaxin works by using an inactivated form of the whole SARS CoV2 virus, which has no potential to affect or infect the body. This kind of Whole-Virion Inactivated vaccine has been used for decades. In fact, this is one of the first forms of large scale vaccines since modern vaccines were developed.

Covishiled uses only a small part of the virus, a spike protein that can be found on the virus surface. This spike protein is used by the virus to enter into human cells, it is also one of the prime ways our immune system can identify the intruder. By replicating just the spike protein and injecting it into the blood, the body can recognize the virus and destroy it. All this, without any risk of contracting the disease since there is no actual virus present.

Both Covaxin and Covishield are excellent vaccines, considering the ridiculously short development times. And both also require two shots for the best results. But it has been thought for some time now that mixing the vaccines, i.e., one shot each of Covishield and Covaxin (or vice versa), may in fact show better results than just one vaccine on its own. 

Spike-protein neutralizing antibodies are the ones which kill and neutralize the virus after vaccine administration. It was found that after mixing covaxin and covishield there was 4 times more response elicited by body as compared to 2 doses of same vaccine in a hospital based study at AIG hospitals.

Dr. M.G. Kartheeka, MBBS, MD(Pediatrics)

What Were The Results Of The Test?

Conducted in Uttar Pradesh, the test was a result of happenstance when 18 individuals received a mix of dosages instead of getting one vaccine twice. Initially, there was a lot of worry in the public regarding the adverse effects of mixing vaccine types. 

As per the ICMR, these 18 individuals were tested against 80 individuals who received the conventional, two doses of 1 vaccine type (40 each of Covishield and Covaxin). Not only were all three of these groups found to be better protected and show greater immunogenicity in general but the group with mixed vaccines showed even better results than the other two groups. 

Effectiveness against the Alpha, Beta and Delta variants was strong and their antibody response was also superior to those who received only one vaccine type. 

Mixing vaccines may enhance the immune response, and it increases flexibility for when people need a booster dose but doses of the vaccine they first received are not available, the same is authorized by the U.S. Food and Drug Administration (FDA).

Dr. Ashish Bajaj , M.B.B.S., M.D. in Clinical Pharmacology and Toxicology

But Is Mixing Covishield And Covaxin Safe?

The safety of mixing vaccines was also looked into by this test, to review its viability for use in the general public. The good news is that no adverse effects were noticed in the short or long term. Pain at the injection site (the upper arm in most cases) was detected, however, this issue is common in other vaccines as well. 

The findings from this study are extremely important in light of the Delta and other variants, since combining Covishield and Covaxin has a better response against them. But not only does a mixed vaccination elicit a better immune response, but it is also a new pathway for vaccinating more people. 

With over a billion people requiring vaccination in the country, the ability to mix and match with Covishield and Covaxin may open up better coverage for vaccinating the country. To move forward and make this a serious option, a broader study across multiple centres will be required. Till then, we can all breathe a sigh of relief at the good news and hope for the best. 

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