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.
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.
The study recommended citizens to remain updated with the latest vaccines in order to prevent severe illness and hospitalizations caused due to Covid-19. US president Joe Biden’s top medical advisor Anthony Fauci also highlighted that a fourth dose could be needed to better people who mount weaker immune responses.
Israel earlier in January was the only nation which recommended a fourth dose to all its adults to enhance protection against Covid-19. In Israel, only the elderly, the immuno-compromised and the population over the age group of 60 years are the only ones who are eligible for the fourth dose.
The Israeli health ministry made the recommendation based on the finding that those who were administered with the fourth vaccine shot or booster were three-to-five times as protected against serious illness and twice as protected against infection. The study included 400,000 Israelis who received the fourth vaccine and 600,000 who received three doses.