Vaccine Central

Delaying Pfizer’s second dose boosts immune response: new study

INDIANAPOLIS (WISH) — Holding off on Pfizer’s second shot for three months was shown to produce more antibodies against COVID-19 than when recipients were vaccinated at the three-week interval, according to a new study by United Kingdom researchers.

The country announced Dec. 30 it would delay second shots by 12 weeks in an effort to ration supply, but the lag also ended up being beneficial in terms of immune response. 

Researchers assessed 175 vaccine recipients older than 80. Some received their second doses three weeks later while others received it from 11-12 weeks later. Those forced to wait presented an antibody response 3.5 times higher than their counterparts.

“This study supports a growing body of evidence that the approach taken in the U.K. for delaying that second dose has really paid off,” said co-author Gayatri Amirthalingam in a news release.

The epidemiologist also said the results could “inform vaccine scheduling decisions in other countries.” The study was a first of its kind. 

“They made the strategic decision early on to vaccinate as many people as they could with one dose to get some protection to nearly everyone,” Dr. Christopher Doehring, vice president of medical affairs at Franciscan Health, told News 8. “There was some concern about what level of protection people would get with only one dose … but bottom line is this is encouraging.”

Doehring says while antibody levels are a good outcome measure, more research is needed to determine if this dosing protocol prevents COVID-19 hospitalizations and deaths. Until then, he recommends sticking to the current three week time-frame based, which is based on clinical trial results. 


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