As the delta strain continues to infect the vaccinated and unvaccinated, the need for a booster shot is being discussed by the FDA and the administration . Breakthrough cases among the vaccinated are several times less than the unvaccinated cases (11 times less according to one study). The efficacy of mRNA vaccines, such the Pfizer-BioNTech and Moderna over time were reviewed by the Centers for Disease Control and Prevention (CDC), as they consider the feasibility of a third or booster dose.

The CDC report collected data from eighteen states between March and August 2021 and put forth the following findings:

• The Pfizer-BioNTech vaccine decreased the risk of hospitalizations due to a COVID-19 infection by 91 percent in the first four months after a person has been fully vaccinated with two doses. However, the efficacy dropped to 77 percent after this period of time.
• The Moderna vaccine faired much better as it decreased the risk of hospitalizations due to a COVID-19 infection by 93 percent in the first four months after a person has been fully vaccinated with two doses. The efficacy of the vaccine remained at 92 percent after four months.

Researchers from the nation found huge differences between the two mRNA vaccines, although they were initially thought to be interchangeable. Although they use the same technology – mRNA, they are formulated and administered differently according to Dr. Timothy Brewer, a professor of medicine and epidemiology at UCLA.

The Moderna vaccine contains 100 micrograms of vaccine while the Pfizer vaccine contains 30 micrograms which is about one third of that which is present in the Moderna vaccine. The Moderna vaccine’s two doses are given four weeks apart while Pfizer’s vaccine two doses are given three weeks apart. Brewer also said that the Moderna vaccine seemed to give higher levels of a key antibody when compared with Pfizer.

Pfizer has been looking for approval from the FDA for its third dose or booster shot. It has presented studies conducted by the company in the U.S. as well as in Israel.

As of now the FDA advisory panel has unanimously agreed that the third dose of the vaccine sold under   the brand name Corminaty by Pfizer should not be made available to all until sufficient research emerges. However, select groups should get the booster or third dose. These groups   include

• individuals who are 65 and older
• those who are at a risk of development severe disease
• those whose jobs put them at high risk of getting infected with COVID-19 including health care workers.

Source https://news.yahoo.com/big-gap-between-pfizer-moderna-034719881.html