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Study: Delaying Pfizer 2nd dose increases protection for older people

Syringes containing the Pfizer-BioNTech COVID-19 vaccine sit in a tray in a vaccination room at St. Joseph Hospital in Orange, Calif., Thursday, Jan. 7, 2021. (AP Photo/Jae C. Hong)

Waiting for a second dose of the Pfizer COVID-19 vaccine may offer older people more protection than getting the jab on time, according to a new study.

Researchers in the U.K. looked at 175 people over the age of 80 — giving half their second Pfizer shot at the three-week interval recommended by the drug maker, and making the other half wait 12 weeks for their final dose.

They found the antibody response of those who waited was three-and-a-half times greater than in those who had the second shot within the recommended time frame.


University of Toronto infectious diseases specialist Dr. Isaac Bogoch shared the study on Twitter, saying the results are exactly what the National Advisory Council on Immunization (NACI) said would happen.

Back in March, the panel recommended second shots be delayed by up to four months to ensure more people could get a first dose, sooner.

Pfizer recommends a 21-day interval between its two shots, while Moderna recommends four weeks and Oxford-AstraZeneca advises between four and twelve weeks.