US considers approving 4th dose of Covid-19 vaccine

The US Food and Drug Administration (FDA) is considering licensing a fourth dose of the Covid-19 vaccine (second booster dose) this fall.

According to a source familiar with the matter, the planning is still in the early stages. The licensing process will depend on ongoing research. Scientists need to determine if the fourth dose improves the ability to protect users, reducing the risk of severe and severe disease after Covid-19 infection.

The FDA has begun reviewing the data to make a decision. Two vaccines under consideration for approval are Pfizer and Moderna. The question now is whether a fourth dose of the vaccine should be given to the general public, or only to specific age groups, and whether a specific vaccine that targets Omicron is needed.

According to experts, the second booster dose could be the start of an annual Covid-19 vaccination program. If a new strain appears, it is likely that the US will apply this strategy.

A fourth dose of the vaccine in the fall can be helpful because it coincides with the annual flu shot. The potential drawback of this strategy is that it causes many people to tire of routine vaccinations after the first dose, while others hesitate to have too many vaccines. Currently, about 65% of the US population is fully immunized, according to the Centers for Disease Control and Prevention (CDC). About 43% received booster injections.

People are injected with a booster dose of vaccine in the Bronx city, USA, January 2022. Photo: NY Times

However, the proportion of older adults and those at risk of contracting the virus has increased, many of whom are eager to receive a fourth dose.

After studies found that vaccine protection diminished over time, health authorities began recommending booster doses to the hesitant group. According to experts, booster doses can improve immunity that has weakened several months after the first vaccination.

The basic course of the Pfizer and Moderna vaccines is two doses, given several weeks apart. The CDC recommends a third dose of Pfizer injected at least 5 months after the second dose.

Experts have long debated whether a fourth dose of vaccination is needed, especially against highly transmissible strains such as Omicron or new strains emerging in the future.

Some studies have shown that the protection of mRNA vaccines after the third dose is generally still strong, but hospitalization rates in the community have been higher. In November-December 2021, after the dominant Omicron strain in the US, the ability to protect users from hospital admission of three doses of vaccines decreased from 91% to 78%.

Thuc Linh (According to WSJ)


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