HomeNewsTrendsHealthNew CDC study shows major drop in efficacy of booster shots after fourth month: Report

New CDC study shows major drop in efficacy of booster shots after fourth month: Report

The CDC also highlighted that this new finding indicates that additional dose or a fourth dose may be required to enhance protection.

February 12, 2022 / 08:50 IST
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The US Centres of Disease Control and Prevention (CDC) on Friday said that the efficacy of the third doses of the Pfizer and Moderna mRNA vaccines starts falling by the fourth month after being administered, news agencies reported.

The CDC also highlighted that this new finding indicates that additional dose or a fourth dose may be required to enhance protection. While countries are yet to achieve the fully vaccinated target, which means vaccinating citizens with the first two doses, and only some have rolled out boosters, this finding raises new challenges.

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The CDC study showed that protection from booster shots of the aforementioned Covid-19 vaccines in cases of Covid-induced emergencies or emergency room visits dropped from 87% in two months to 66% by the fourth month after the third dose. However, when it came to protection from hospitalizations, booster efficacy dropped from 91% in the first two months after a third dose to 78% around the fourth month, the study highlighted.


The study was conducted between August last year and January 2022 and was based on more than 241,204 visits to the hospital’s emergency section for Covid-related complications and was also based on 93,408 hospitalizations of serious nature.

COVID-19 Vaccine
Frequently Asked Questions

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How does a vaccine work?

A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

How many types of vaccines are there?

There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

What does it take to develop a vaccine of this kind?

Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
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