Sinovac Booster Offers Older Adults Stronger Protection Against Omicron, Study Finds

Two doses of China’s Sinovac vaccine only offered the elderly a moderately high level of protection against serious illness and death fr...


Two doses of China’s Sinovac vaccine only offered the elderly a moderately high level of protection against serious illness and death from Covid-19, but a third dose significantly boosted their defenses, according to a new study by scientists in Hong Kong.

The study, based on patients infected during the current devastating crisis Omicron wave in Hong Kong, serves as a cautionary tale for mainland China, where Sinovac is a mainstay of the country’s immunization program. Many seniors have yet to receive a reminder.

For people 60 and older, two doses of Sinovac were 72% effective against severe or fatal Covid-19 and 77% effective against Covid-related deaths, the study found. These levels of protection were lower than those provided by two doses of Pfizer-BioNTech. The same study found they were 90% effective against severe or fatal Covid and 92% effective against death among Hong Kong residents of the same age group.

A booster shot of Sinovac helped significantly, proving 98% effective against severe or fatal Covid in people aged 60 and over, according to the study.

Yanzhong Huang, global health expert at the Council on Foreign Relations, said the findings underscored the urgency for mainland China to speed up its overdue recall campaign. “The government has a lot of work to do to ensure that this segment of the population gets the booster shots,” he said.

The study authors, who are scientists from the University of Hong Kong, noted that the city’s booster program started recently, making it difficult to determine how long protection from a third dose would last.

Because people with underlying health conditions in Hong Kong were more likely to resist vaccination, they said, it was also possible that those who chose to be vaccinated or boosted were healthier in the first place. , inflating estimates of initial vaccine protection. were.

Sinovac, a private Chinese company that manufactures the vaccine, is one of two manufacturers of Covid vaccines available in China. Vaccines using mRNA technology, such as those made by Pfizer-BioNTech and Moderna, are not available there.

The new study highlights the potential consequences for China, which has relied heavily on Sinovac and is battling its biggest Covid outbreak in two years. More than 87% of the Chinese population has been vaccinated. But just over half of people aged 80 and over have received two injections, and less than 20 percent of people in that age group have received a booster, Zeng Yixin, vice minister of the National Commission, said recently. of health.

The new Hong Kong study has received funding from the Chinese Center for Disease Control and Prevention as part of what one of the study’s co-authors described this week as an effort to understand comparative effectiveness vaccines. It has been published online as a preprint, but has not yet been approved by scientific peers for publication in a scientific journal.

Sinovac’s vaccine worked the same as Pfizer’s in young people, even without a booster dose, according to the study. In people under 60, two doses of Sinovac were about 92% effective against severe or fatal Covid, while two doses of Pfizer were about 95% effective.

Neither vaccine provided much protection against mild or moderate Covid, although Pfizer’s offered more than Sinovac’s and a booster dose significantly increased levels of protection. During the last wave, people in Hong Kong were widely infected with the subvariant of Omicron known as BA.2. Like other versions of Omicron, BA.2 has infected many vaccinated people.

Hong Kong’s surge is killing people at a rate faster than nearly any country since the coronavirus emerged – a result, in large part, of low vaccination rates among older residents. Almost 90% of those who died in the last wave were not fully immunized, suggesting that getting the most vulnerable vaccinated is more important than the particular brand of vaccine.

Like Hong Kong, mainland China had largely succeeded in curbing transmission of the virus before Omicron, leaving its population with very little immunity to previous infections.

Beyond China, Sinovac vaccines have also played a critical role in protecting people from severe Covid cases, especially in poorer countries. The vaccine is used in 49 countries, including South America and Africa.

But concerns about the protection it offered had already prompted the World Health Organization to recommend in october that beneficiaries aged 60 and over receive a third dose.

Dr Andrew Morris, an infectious disease specialist at Sinai Health and University Health Network in Toronto, who was not involved in the Hong Kong study, said the results were consistent with laboratory studies suggesting that Sinovac generated lower levels of neutralizing antibodies than mRNA vaccines, such as those from Pfizer.

“I think what we’ll see is that in countries that have relied heavily on Sinovac, if they don’t have a booster – especially with an mRNA booster, or even with Sinovac – they will probably struggle with high infection rates with this latest BA.2 wave,” he said.

Dr Morris said the results in Hong Kong, like those of other vaccine studies, also depended heavily on how long since people had received the injections. The protection tends to weaken over time.

The results of the latest study on the effectiveness of third doses of Sinovac could be taken as an encouraging sign by Chinese leaders that Chinese-made vaccines could remain at the center of their vaccination campaign, said Dr Huang, from the Council. on Foreign Relations.

“Now for Chinese leaders, they don’t need to face heavy pressure to approve BioNTech’s vaccine,” he said.

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Newsrust - US Top News: Sinovac Booster Offers Older Adults Stronger Protection Against Omicron, Study Finds
Sinovac Booster Offers Older Adults Stronger Protection Against Omicron, Study Finds
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