Sinovac Booster Gives Elderly Stronger Protection Against Omicron, Study Finds

Two doses of the Chinese Sinovac vaccine gave the elderly only moderately high levels of protection against severe illness and death from Covid-19. But a third dose significantly boosted their defenses. new study by scientists from Hong Kong.

Based on patients infected during the current devastating Omicron wave in Hong Kong, the study serves as a cautionary tale for mainland China, where Sinovac is the backbone of the country’s vaccination program. Many older people have yet to receive booster shots.

The study found that for people aged 60 and over. Two doses of Sinovac were 72% effective against severe or fatal Covid-19 and 77% effective against Covid-related death. The same study found them to be 90% effective against severe or fatal Covid and 92% effective against death among Hong Kong residents of the same age group. These levels of protection were lower than those provided by two doses of Pfizer-BioNTech.

The study found that the Sinovac booster helped significantly, being 98 percent effective against severe or fatal Covid in people aged at least 60.

Yanzhong Huang

Yanzhong Huang, the global health expert at the Council on Foreign Relations, said the results highlight the urgent need for mainland China to accelerate its lagging support campaign. “The government needs to do a lot of work to make sure this population segment gets extra shots,” he said.

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

Because people with comorbidities in Hong Kong were more likely to resist vaccination. They said it’s also possible that those who chose to get vaccinated or revaccinated were healthier in the first place, inflating estimates of how protective the vaccines were initially.

Sinovac, a privately-held Chinese vaccine company, is one of only 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.

A new study highlights the potential implications for China, which has relied heavily on Sinovac and is battling its biggest Covid outbreak in two years. More than 87 percent of the Chinese population has been vaccinated. But just over half of people aged 80 and over received two shots. Less than 20 percent of people in that age group received a booster. National Health Commission Vice Minister Zeng Yixin recently said.

A new study out of Hong Kong has received funding from the China Centers for Disease Control and Prevention in what one of the study’s co-authors described. This week is an attempt to understand the relative effectiveness of vaccines. It has been posted online as a preprint but has not yet been reviewed by fellow scientists for publication in a scientific journal.

The study showed that the Sinovac vaccine works the same as the Pfizer vaccine in young people. Even without a booster dose. In people younger than 60, two doses of Sinovac were about 92% effective against severe or fatal Covid. At the same time, two doses of Pfizer were about 95% effective.

None of the vaccines provided sufficient protection against mild to moderate Covid. Although Pfizer offered more than Sinovac, a booster dose significantly increased the level of security. During the latest wave, people in Hong Kong mainly were infected with a sub-variant of Omicron known as BA.2. Like other versions of Omicron, BA.2 has infected many vaccinated people.

The wave in Hong Kong has been killing people at a rate faster than almost any country since the outbreak of the coronavirus. Largely the result of low vaccination rates among older residents. Nearly 90 percent of the people who died during the latest wave were not fully immunized. Suggesting that making the vaccines most vulnerable is more important than a particular brand of vaccine.

Like Hong Kong, mainland China has succeeded mainly in suppressing pre-Omicron transmission of the virus. He is leaving its populations with very weak immunity from previous infections. Sinovac vaccines have also played a critical role in protecting people from severe Covid. Especially in poorer countries. The vaccine is used in 49 countries, including South America and Africa.

But concerns about the protection it offers have already prompted the World Health Organization to recommend in october that recipients aged 60 and over receive a third dose in October.

Dr. Andrew Morris

Dr. Andrew Morris is 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 are consistent with laboratory studies suggesting Sinovac produces lower levels of neutralizing antibodies than mRNA vaccines. Like Pfizer.

“I think we will see that in countries that have relied heavily on Sinovac. They don’t have booster immunizations — especially with an mRNA booster or even Sinovac. They are likely to struggle with high rates of virus infection. This latest wave of BA.2,” he said.

Dr. Morris said the results in Hong Kong, like those of other vaccine studies. Protection weakens over time. It also depends heavily on how long it has been since people were vaccinated.

Chinese leaders could take the latest study results on the effectiveness of third doses of Sinovac as an encouraging sign. That Chinese vaccine can remain the focus of their immunization campaign, said Dr. Huang of the Council on Foreign Relations.

“Now Chinese leaders don’t have to face intense pressure to approve BioNTech’s vaccine,” he said.

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