In terms of deaths per 100,000 people, there were 11 for those immunized with Sinovac and 7.8 for the Sinopharm vaccine, the state-affiliated Straits Times newspaper reported. The rate dropped for people who received messenger RNA — or mRNA — vaccines, with 6.2 deaths for Pfizer-BioNTech and one fatality for Moderna.

“These rates are only indicative since they do not account for other factors which can affect mortality, such as the age and timing of vaccination,” Ong said Monday.

While the sample size offered by Singapore is small, the data adds to concerns about the efficacy of so-called “inactivated virus” vaccines, which are in widespread use in China and much of the developing world. Such vaccines have a higher incidence of breakthrough infections and may be less effective against the highly transmissible omicron variant. (Major Chinese pharmaceutical companies, including Sinopharm and Sinovac, say they are working to create vaccines using mRNA technology.)