Pfizer Gears Up to Issue Third COVID Shot; What We Know So Far

Pfizer released data on Wednesday that suggests a third dose of its COVID-19 vaccine co-developed with BioNTech can "strongly" increase someone's protection against the Delta variant.

The company posted the data online, which details how effective its vaccines are against the highly contagious coronavirus variant when a third booster shot is administered. The research finds that getting a third dose of the vaccine at least six months after the second dose produced significant amounts of neutralizing antibodies the work against the Delta and Beta variants.

Antibody levels against the Delta variant in people ages 18 to 55 who received a booster are greater than five-fold than after a second dose, according to the research. For people ages 65 to 85 who received a third dose, the data shows antibody levels are greater than 11-fold than following a second dose.

The research claimed there is an "estimated potential for up to 100-fold increase in Delta neutralization post-dose three compared to pre-dose three."

Covid-19 Vaccine
Pfizer research released on Wednesday states a third dose of its COVID vaccine strongly boosts protection from the Delta variant. In this photo, a nurse administers the Pfizer/BioNTech COVID-19 vaccine at a mobile vaccine clinic on July 16, 2021, in Los Angeles, California. Frederic J. Brown/AFP/Getty Images

The data, which has not been peer-reviewed or published, also showed that antibody levels are much higher after a third dose against the original coronavirus variant and the Beta variant, which was first detected in South Africa.

Pfizer had previously announced that clinical trials are scheduled to start for booster shots in August.

Earlier this week, the Centers for Disease Control and Prevention (CDC) announced new recommendations that even vaccinated people should wear masks indoors in parts of the U.S where the coronavirus is surging due to the Delta variant.

The nation is currently averaging more than 57,000 COVID-19 cases a day and 24,000 COVID-19 hospitalizations. The CDC said last week that the Delta variant is believed to account for 83 percent of sequenced COVID-19 cases in the United States. In areas of the country with low vaccination rates, the variant may be responsible for 90 percent of the cases.

Most new infections in the U.S. are said to be coming from unvaccinated people. However, "breakthrough" infections can occur in vaccinated people, though these infections are said to generally cause milder illness.

During a July 20 Senate hearing, CDC Director Dr. Rochelle Walensky said that when earlier strains of the virus were the dominant cause of infections, vaccinated people who had breakthrough infections were found to have low levels of the virus and were thus deemed unlikely to spread the virus much. She also cited the new 83 percent, noting it represented "a dramatic increase" from 50 percent of sequenced cases that were documented during the week of July 3.