Study: Antibody levels 2.4 times higher after COVID-19 booster

The Yomiuri Shimbun

16:00 JST, January 28, 2022

People who had received a third dose of Pfizer Inc.’s COVID-19 vaccine had 2.4 times the level of antibodies compared to when they received their second dose, according to a team of Japanese researchers.

Overseas studies have already demonstrated that a third shot is more effective in preventing the onset of the disease and the severity of coronavirus symptoms.

The same results have been confirmed in tests conducted to Japanese people by the Kawasaki Medical School in Kurashiki, Okayama Prefecture, which released its findings on Thursday.

Health care workers have been offered booster shots since December. As of Wednesday, 3.15 million people, or 2.5% of the population, had received a third vaccine shot.

The research team examined antibody levels in 500 health care workers aged 20-79. A comparison of samples taken on two occasions — four weeks after the second and third shots — showed antibody levels were 2.4 times higher after the third dose.

A survey of 250 booster recipients revealed that 36% suffered fever, compared to 31% after the second shot. However, fewer people said they suffered pain, redness or swelling in the injection area following their third vaccination.

“Adverse reactions after booster shots seem to be on roughly the same level as those seen after the second dose,” said Shin Ohira, a research team member who specializes in infectious diseases.