(Reuters) – A booster shot of the Pfizer/BioNTech COVID-19 vaccine appears to provide strong protection, at least in the short term, according to data from Israel.
The odds of testing positive for the coronavirus were much lower in adults who received a third dose of the vaccine than in people who got their second dose more than five months ago, the data showed.
Researchers with Maccabi Health Services reviewed data on PCR tests performed in more than 306,000 adults after the Pfizer/BioNTech booster dose became widely available. Roughly half the tests were done in people who had received a booster and half in people who had received only the standard two doses, with at least five months since the second dose.
Overall, 1.8% of tests were positive in the booster group, versus 6.6% among those with only two doses, the researchers reported last week in JAMA Internal Medicine.
After taking participants’ various risk factors into account, the researchers estimated that between four and nine weeks after receipt, the third shot was associated with an 86% reduction in the odds of testing positive for the virus. Results were similar when they compared subsets of closely matched recipients of two or three doses.
The vaccine’s waning of protection over time “seems to be counteracted in the short-term by a third dose,” but longer monitoring is needed to see how long the protection will last, the researchers said.
SOURCE: https://bit.ly/3oCrLS1 JAMA Internal Medicine, online November 30, 2021.
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