Officials seek to boost vaccines’ effectiveness

A senior Chinese official said the country’s vaccines may need to be administered in greater doses or in concert with other shots because of their low overall effectiveness.

Saturday’s comments by Gao Fu, director of China’s disease-control center, suggest China and more than 60 countries that have approved Chinese vaccines could need to adjust their distribution programs. The widespread distribution of Chinese vaccines means any changes could potentially affect hundreds of millions of people or more.

Possible steps to boost effectiveness of Chinese vaccines include changing the amount of vaccine given, the number of shots, the time between shots or the type of vaccines given, Gao said.

He also praised the possibilities offered by messenger RNA. That technology is used in the Moderna and PfizerBioNTech vaccines but not in any of the vaccines thus far approved in China.

Officials in Brazil said in January that the efficacy rate for the CoronaVac vaccine from the Beijing-based company Sinovac was just over 50 percent. By comparison, Moderna and PfizerBioNTech were found to be 90 percent effective in real-world conditions, researchers said last month.

Last month, the distributor in the United Arab Emirates of vaccines from China’s Sinopharm said it was offering a third dose in addition to the standard two-dose regimen for a “very small number” of people who were “not really responsive” to the vaccine.