Jahnavi Sarma
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Written By: Jahnavi Sarma | Published : April 20, 2021 11:40 AM IST
अगर बूस्टर डोज को अप्रूल मिला तो पहले ये कमजोर इम्युनिटी वाले लोगों को लगाई जाएगी.
Since the beginning of the COVID-19 pandemic in 2019, the virus may have produced thousands of variants. But most of these variants disappeared. Some, however, survived. Mutations like the UK (B117), South Africa (501Y.V2) and Brazil (B11248) variants mutated in such a way that it helped the virus survive and reproduce. The COVID-19 virus is still mutating, it is producing many new variants and spreading alarmingly across the world. Experts are of the opinion that while the available vaccines may be able to hold fort against these new variants, it is not yet known how long our immunity will last. Hence, a third booster vaccine or an annual vaccine may be the key to protecting people against the virus.
A health expert from Amrita Institute of Medical Sciences, Kochi, told IANS that emerging data suggests that there is a likelihood that immunity may wane over time and given the increasing trend in the emergence of virus variants of concern, there is a high likelihood of booster doses. A third booster will help since new variants are emerging and not much is known about duration of immunity against the virus. Whatever immunity people are gaining with the vaccines, a booster will definitely help.
Currently, all the vaccines require two-doses to be administered, two, three, or four weeks apart, through the intramuscular route. However, a third booster vaccine or an annual vaccine dose like other flu shots may become the normal and help immunity to last longer. However, it remains to be seen when it would be most appropriate to administer the third booster, Menon said.
A booster shot is "a repeat dose of a vaccine that you've already received to literally boost your immunity. US pharmaceutical major Pfizer's CEO Albert Bourla, in a recent statement, announced that Covid vaccine recipients will "likely" need a third dose between six to 12 months after they're fully vaccinated. He also suggested the need for yearly vaccinations against coronavirus.
According to experts, the third booster dose creates virus-fighting memory in the immune system. As a result, it can create a greater and more long-lasting immune response. But it must be noted that the existing vaccines are also well able to suppress the new variants. According to the World Health Organisation, all approved vaccines are expected to provide at least some protection against new variants as protection is mediated by broad immune responses involving both arms of immunity - humoral (antibody dependent) and T cell dependent.
While the Pfizer and Moderna vaccines have shown a reasonable effect against the mutants, the South African and Brazilian mutants are worrisome. Most of the current vaccines, including Oxford- AstraZeneca vaccine, work well against the UK variant but not against the South African mutant. The efficacy in South Africa variant of this vaccine is just 10 to 15 per cent. But it works well against the Brazilian variant and efficacy is around 40 to 50 per cent. India's indigenous vaccine Covaxin has not been tested against these variants and there is no research yet on this.
According to senior personnel of Genestrings Diagnostic Centre, changes or mutations in the virus cannot make vaccines completely ineffective. In the event that any of the current vaccines prove to be less effective against one or more variants, it will be possible to change the composition of the vaccines to protect against these variants.
(With inputs from IANS)
