Study questions effectiveness of Chinese vaccine

BUDAPEST, Hungary — A new study suggests that a Sinopharm vaccine offers poor protection from COVID-19 among seniors, raising questions for dozens of countries that have given the Chinese company’s shots to their most vulnerable populations.

A survey of blood samples taken from 450 people in Hungary at least two weeks after their second Sinopharm dose found that 90 percent under 50 years old developed protective antibodies.

But the percentage declined with age, and 50 percent of those over 80 had none.

The study by two Hungarian researchers was posted online this week but not yet reviewed. Three outside experts said they had no problems with the methodology of the study of the vaccine developed by Sinopharm’s Beijing Institute of Biological Products.

“This is very, very worrying that these people, who are high-risk, have a poor antibody response,” said Jin Dong-yan, a Hong Kong University virologist who was not affiliated with the study.

Antibody levels are not a direct measure of how protected a person is from COVID-19, but there is evidence they are a good proxy. One expert cautioned that the choice of test kits could have limited the accuracy.

But the study’s findings have value and are the first public, scientific attempt to analyze the effect of the Sinopharm vaccine in the senior population, said Wang Chenguang, a former professor at Peking Union Medical College and an immunology expert.

China’s National Health Commission declined to comment, saying it would respond only to studies by governments or major research institutions.

The vaccine was given a greenlight by the World Health Organization in May and is being used in more than 50 countries.