Pfizer’s COVID-19 vaccine effectiveness drops after 6 months: study

The effectiveness of the Pfizer Inc /BioNTech SE vaccine in stopping an infection by the coronavirus dropped to 47% from 88% six months after the second dose, in line with knowledge printed on Monday that U.S. well being businesses thought of when deciding on the necessity for booster photographs.

The info, which was printed within the Lancet medical journal, had been beforehand launched in August forward of peer assessment.

The evaluation confirmed that the vaccine’s effectiveness in stopping hospitalization and demise remained excessive at 90% for at the very least six months, even in opposition to the extremely contagious Delta variant of the coronavirus.

The info means that the drop is because of waning efficacy, quite than extra contagious variants, researchers mentioned.

Researchers from Pfizer and Kaiser Permanente studied digital well being information of roughly 3.4 million individuals who have been members of Kaiser Permanente Southern California between December 2020 – when the vaccine first turned accessible – and August of 2021.

“Our variant-specific evaluation clearly exhibits that the (Pfizer/BioNTech) vaccine is efficient in opposition to all present variants of concern, together with Delta,” mentioned Luis Jodar, senior vp and chief medical officer at Pfizer vaccines.

A possible limitation of the examine was a scarcity of knowledge on adherence to masking tips and occupations within the examine inhabitants, which may have affected frequency of testing and probability of publicity to the virus.

Vaccine effectiveness in opposition to the Delta variant was 93% after the primary month, declining to 53% after 4 months. In opposition to different coronavirus variants, efficacy declined to 67% from 97%.

“To us, that implies Delta shouldn’t be an escape variant that’s fully evading vaccine safety,” mentioned examine chief Sara Tartof with Kaiser Permanente Southern California’s Division of Analysis & Analysis.

“If it was, we might in all probability not have seen excessive safety after vaccination, as a result of vaccination wouldn’t be working in that case. It could begin low, and keep low.”

Testing for variants is extra more likely to fail in vaccinated people, which may result in overestimation of variant-specific effectiveness within the examine, the authors cautioned.

The U.S. Meals and Drug Administration has licensed the usage of a booster dose of the Pfizer/BioNTech vaccine for older adults and a few Individuals at high-risk of getting contaminated. Scientists have referred to as for extra knowledge on whether or not boosters needs to be advisable for all.

(Reporting by Manas Mishra in Bengaluru; Enhancing by Invoice Berkrot)

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