Pfizer/BioNTech COVID-19 vaccine effectiveness drops after 6 months, study shows

Michigan Oct 5 (U.S.): The effectiveness of the Pfizer Inc/BioNTech SE vaccine in preventing infection with the coronavirus has fallen to 47% from 88% six months after the second dose, according to data published on Monday considered by US health agencies. When deciding on the need for booster doses.

The data, published in The Lancet medical journal, was previously published in August before peer review.

The analysis showed that the vaccine’s effectiveness in preventing hospitalization and death remained high by 90% for at least six months, even against the highly contagious delta variant of the coronavirus.

Researchers said the data suggest the decline is due to waning efficacy, rather than more infectious variants.

Researchers from Pfizer and Kaiser Permanente studied the electronic health records of nearly 3.4 million people who were members of Kaiser Permanente Southern California between December 2020 — when the vaccine first became available — and August 2021.

“Our type-specific analysis clearly shows that the (Pfizer/BioNTech) vaccine is effective against all current variants of concern, including Delta,” said Louis Godard, senior vice president and chief medical officer of Pfizer Vaccines.

One potential limitation of the study was the lack of data on adherence to concealment and occupational guidelines in the study population, which may affect the frequency of testing and the likelihood of exposure to the virus.

Vaccine efficacy against the delta variant was 93% after the first month, and decreased to 53% after four months. Against other coronavirus variants, efficacy has fallen to 67% from 97%.

“To us, this suggests that delta is not a surrogate for escape that completely avoids vaccine protection,” said study leader Sarah Tartoff of Kaiser Permanente Southern California.

“If that’s the case, we may not have seen high protection after vaccination, because in this case vaccination won’t work. It will start low, stay low.”

The authors cautioned that testing of variants is more likely to fail in vaccinated individuals, which may lead to an overestimation of the efficacy of the variants identified in the study.

The U.S. Food and Drug Administration has authorized the use of a booster dose of the Pfizer/BioNTech vaccine for older adults and some Americans at risk of infection. Scientists have called for more data on whether reinforcers should be recommended for everyone.

HF