China’s CanSinoBIO says its vaccine may be less effective over time, but ‘booster shot’ improves its efficacy to over 90%

A single-shot Covid-19 vaccine by CanSino Biologics has shown a decrease in efficacy over time, the manufacturer has said. Getting a “booster shot” six months after the first jab, however, propels its efficacy to over 90%.

The Chinese vaccine manufacturer CanSinoBIO provided an update on its vaccine during an online presentation late on Wednesday. Its chief scientific officer, Zhu Tao, said receiving a second jab of the vaccine six months after being inoculated with the single-shot solution had shown promising results during tests.

“A booster shot six months later led to a seven-times to 10-times increase in neutralizing antibody levels, so we expect in this case efficacy could reach over 90%,” Zhu stated.

While the first shot’s efficacy may fall over time, it is still believed to be some 50% effective or more five to six months after inoculation. Nonetheless, more clinical trials data is needed in order to provide more precise estimates, Zhu warned.

The company published first interim trials data back in February, with the vaccine showing a rather modest efficacy of nearly 69% in preventing asymptomatic Covid-19. Its efficacy then steadily dropped over time, measuring some 65% four weeks after the inoculation.

So far, CanSinoBIO’s vaccine has been approved only by a handful of countries, including China, Pakistan, and Mexico. Last week, it also received emergency use approval in Hungary, becoming the second Chinese-made vaccine to be greenlit by the European country.

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