A new study finds a booster dose of the Sinovac SARS-CoV-2 vaccine is highly effective at preventing severe or fatal disease among individuals 60 years old or older, the New York Times reports.
Researchers from the University of Hong Kong examined the effectiveness of one, two, and three doses of the Sinovac vaccine to that of the Pfizer-BioNTech vaccine among Hong Kong residents. As they report in a preprint posted to MedRxiv, the researchers found that among people 60 years old and older two doses of the Sinovac vaccine was 74.1 percent effective in preventing severe disease and death, as compared to 88.2 percent for the Pfizer-BioNTech vaccine.
A booster dose bumped that up. Three doses of either vaccine led to 98.1 percent effectiveness in protecting against severe disease, the researchers found.
Andrew Morris from Sinai Health and University Health Network in Toronto, tells the Times that the findings are in line with those from other studies suggesting the Sinovac generates lower neutralizing antibodies than mRNA-based vaccines.
"I think what we'll see is in countries that have relied heavily on Sinovac, if they don't have boosting — especially with an mRNA booster, or even with Sinovac — they're probably going to struggle with high rates of infection with this latest BA.2 wave," he adds there.
The World Health Organization recommended in October that people 60 years old or older who received the first two doses of the Sinovac SARS-CoV-2 vaccine seek a third dose.