Sinovac’s Vaccine Found Inferior to Pfizer Shot in Chile Study


Sinovac Biotech Ltd.’s vaccine was less potent than Pfizer Inc.’s at stopping Covid-19 in Chile where the two shots were used simultaneously, allowing the first real-world comparison of the two inoculations.

China’s CoronaVac was 66% effective in preventing Covid among fully vaccinated adults, compared with 93% or the jab made by Pfizer and its partner BioNTech SE.

The research shows both shots protect against severe disease. Sinovac’s inactivated inoculation, given to more than 10 million Chileans, was slightly less effective in preventing hospitalization and deaths than Pfizer’s messenger RNA vaccine, which was administered to fewer than half a million people, according to the study, published in the New England Journal of Medicine.

The research was conducted from February through May, when the alpha and gamma strains of the virus were the variants most frequently detected in Chile.

A clinical trial reported in The Lancet shows better results, pointing to 83.5% protection against symptomatic Covid and mild reactions to the shot. The interim data comes from a phase 3 trial conducted in Turkey on more than 10,000 participants.

Both sets of data -- the real-life one from Chile and the clinical study from Turkey -- suggest CoronaVac provides an effective shield against the virus.

Chile’s Ministry of Health has administered almost 14 million CoronaVac doses as of May 10, enough to fully immunize 6.36 million people. In comparison, 2.4 million doses of the Pfizer-BioNTech vaccine had been administered. Individuals 16 years or older are eligible, according to the national vaccination schedule.

Comparative effectiveness data are given below:

Covid-19HospitalizationICU admissionDeath

The study was funded by Chile’s National Research and Development Agency.

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