BEIJING, Dec. 13 (Xinhua) -- A leading Chinese immunologist on Tuesday said that not many people aged 60 and above have had adverse reactions to COVID-19 vaccination.

An elderly resident has his blood pressure checked before receiving his shot of COVID-19 vaccine at home in Beijing, May 10, 2022. (File photo: Xinhua)

Wang Huaqing, chief immunologist at the Chinese Center for Disease Control and Prevention, said the ratio of adverse reactions was lower among the elderly population (aged 60 and above) than among the younger population (aged below 60).

The ratio of severe adverse reactions among the elderly population was similar to other age groups, or below one in 1 million, he added.

Wang said it normally takes one to two weeks to develop antibodies after vaccination, and relatively high levels of antibodies are achieved four weeks after a full vaccination course.