Anti-Coronavirus vaccine antibodies fall by 30% after six months

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BEIJING, Aug 6 - Antibody levels in people that are inoculated with CanSino Biologics single dose COVID-19 vaccine fell by some 30% after six months. However a booster shot could offer a significant lift, a senior executive said late on Thursday morning.

The decline in antibodies does not necessarily mean the shots will lose their protection, though how fast they wane could still serve as an important indicator of the immune response, Zhu Tao, chief scientific officer at CanSinoBIO, said in an online presentation.

Apart from durable antibodies, researchers say that other components in a person's immune system, such as cells and B cell memory, may also contribute to protection https: www.reuters.com article US-Health - Coronavirus-variants - idUSKBN2 BM 3 BZ.

Six months after being vaccinated with CanSinoBIO shot, neutralising antibodies were at roughly 70% of the level seen 28 days after the shot, Zhu said, citing data from 35 vaccinated people.

When a second dose was given after six months, antibody levels shot up eight fold two weeks later, Zhu said, citing data from 28 people.

Five out of seven vaccinations approved in China are two-shot inactivated vaccines from Sinovac and state-backed Sinopharm which contain killed coronavirus. CanSinoBIO's shot uses a modified common cold virus known as the adenovirus to ferry genetic information of the spike protein of coronavirus into human bodies

A third booster shot of CanSinoBIO vaccine three to six months after the second shot of an inactivated vaccine generated significantly higher antibody levels compared using an inactivated vaccine as a third-dose booster, Zhu said. He cited data from about 200 participants in a clinical trial.