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Pfizer COVID-19 vaccine protection stronger if second dose is delayed, study finds

Syringe
Posted at 1:36 PM, May 18, 2021
and last updated 2021-05-18 13:36:07-04

A study published recently and led by health experts in the United Kingdom found delaying the second dose of the Pfizer COVID-19 vaccine resulted in a stronger antibody response.

The results found antibodies were three-and-a-half times higher when the second dose was given 12 weeks after the first dose, compared to the three-week interval that is currently recommended.

The majority of people are well-protected regardless of the timing of the second shot, but some researchers think the stronger response from the delayed second shot could mean the protection lasts longer; antibody levels naturally wane over time.

The study was led by researchers at the University of Birmingham working with Public Health England and looked at results in patients who are 80 or older.

“We’ve shown that peak antibody responses after the second Pfizer vaccination are really strongly boosted in older people when this is delayed to 11 to 12 weeks. There is a marked difference between these two schedules in terms of antibody responses we see,” Dr. Helen Parry, a senior author on the study, told the Guardian.

At the end of last year, the UK announced they would delay the second dose of the COVID-19 vaccines in order to expand partial immunity for a greater proportion of the population with the first dose.

Researchers were then able to test 175 vaccine recipients’ antibody levels who waited 11-12 weeks for their second dose ofthe Pfizer vaccine.

Pfizer was not a part of this study and said in a statement to Fox News they can only speak to the three-week dosing regime that was tested in their clinical trials.

An earlier study looked at antibody results when patients delayed getting the AstraZeneca COVID-19 vaccine for 12 weeks, and found a similar bump in antibody response.

The AstraZeneca and Pfizer COVID-19 vaccines are both available in the United Kingdom.

While delaying the second dose appears to help with vaccine response, researchers stress a drop in COVID-19 infections in the UK is also because of firm lockdown measures.

“People are theoretically vulnerable between their first and second jab,” Stephen Griffin, a virologist at the University of Leeds told the journal Nature. “What’s worked in the UK is maintaining restrictions at the same time as vaccinating.”