COVISHIELD accounts for 85% of the COVID vaccine doses in India
Now that we are almost done with the double doses of COVID vaccination, it's time to move on to the booster shots or the precaution doses as it is called in India. These doses are said to enhance the memory of the immunity and offer a longer protection to the body against the COVID infection.
In India, various vaccines have been approved for use- of which COVISHIELD, COVAXIN and Sputnik V are used for vaccination drives. The other approved vaccines are: Covovax, ZyCoV-D, the mRNA vaccine developed by Gennova pharmaceuticals, CORBEVAX.
COVISHIELD accounts for 85% of the COVID vaccine doses in India
AstraZeneca's vaccine manufactured by Serum Institute of India, COVISHIELD, accounts for 85% of the vaccine doses given in the country.
The Astrazeneca vaccine, which is known as COVISHIELD at home, is a recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 Spike (S) glycoprotein. Following administration, the genetic material of part of coronavirus is expressed which stimulates an immune response.
In India, COVISHIELD is also being considered as the suitable booster shot though research studies have shown it to be having the lowest neutralizing potential on the Omicron variant.
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Astrazeneca is not considered a “good candidate” for booster shot outside
Many countries have preferred not to use AstraZeneca as a booster shot citing research studies. Though AstraZeneca was the most-used vaccine for first and second jabs in the UK, its use as a booster has been scaled back. Instead the tee on Vaccination and Immunisation (JCVI) has recommended mRNA vaccines for boosters. The AstraZeneca vaccine uses an adenovirus vector instead of mRNA.
Studies have shown that a booster shot of the mRNA vaccine developed by the Pfizer is 95.6 per cent more effective than AstraZeneca. A similar result was also obtained for the mRNA vaccine of Moderna.
"mRNA vaccines provide a strong booster effect, regardless of whether the primary course was with the Pfizer-BioNTech (BNT162b2/ Comirnaty) or the AstraZeneca (ChAdOx1-S/Vaxzevria) vaccine," the UK JCVI had said in September 2021.
To find out the best method of immunising people after the first two shots, a vaccine trial called COV-BOOST was conducted by multiple research centres.
Citing the study, Professor Linda Bauld from Edinburgh University told a leading journal that the mRNA based vaccines, both Pfizer and Moderna, were the most effective as booster jabs. She however said that some people may still receive the AstraZeneca vaccine if they are allergic to the ingredients in the mRNA vaccines. She explained that AstraZeneca exposes people to a modified version of the virus while mRNA creates specific proteins which subsequently trigger the immune system to produce antibodies to attack the virus.
Which countries do not use AstraZeneca for booster shot?
Several European countries have also stopped the use of AstraZeneca: Denmark, Norway, Austria, Estonia, Latvia, Lithuania and Luxembourg.
Is COVISHIELD efficient as a booster dose?
The COVISHIELD manufactured by the Serum Institute of India, is based on the same patent technology as the Astrazeneca vaccine. While other countries have stressed upon mixing of vaccines and introduced mRNA vaccines for better protection, in India COVISHIELD is still the best candidate for booster inoculation.
COVISHIELD accounts for 85% of the COVID vaccines administered in the country. Though several vaccines have been approved by the government, Bharat Biotech's COVAXIN, which is the country indigenous COVID vaccine and COVISHIELD account for 99% of the inoculations.
The country's first mRNA vaccine is yet to be rolled out. As of February, 2022 the mRNA vaccine prepared by Gennova Pharmaceuticals was continuing the clinical trial. Gennova has been funded with ₹125 crore from the Department of Biotechnology (DBT).