China looks overseas for vaccine data in search for way out of Covid-19

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China has administered 2.2 billion doses of Covid-19 vaccines and fully vaccinated 72 per cent of the population, but there is still no sign of relaxing what are arguably the world’s toughest containment rules, including long quarantine periods and strict border controls.

The zero tolerance policy has largely contained the community spread of Covid-19 but it has also prevented assessment at home of how vaccination would affect the epidemic or how long vaccine immunity could protect the population.

To plug that knowledge gap, China plans sponsoring vaccine effectiveness studies in countries where Chinese vaccines are used. The data from the studies will allow authorities to update the immunisation strategy or adjust strict Covid-19 control measures.

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An Zhijie, deputy director of the National Immunisation Programme with the Chinese Centre for Disease Control and Prevention, told a forum in Beijing on the weekend that the Covid-19 Vaccines Overseas Evaluation Programme was part of the China CDC’s effort to help countries conduct real-world vaccine effectiveness studies.

“There is a need for some of our domestically produced vaccines to have effectiveness studies conducted abroad to support our domestic policymaking and widespread international use. The China CDC plans to conduct some vaccine effectiveness studies to fill in the knowledge gap and provide evidence for policymaking,” An said.

The studies will be run by a local institution or a principal investigator attached to a health authority or academic institution in the host country. China may offer grants for such investigations and give technical support if requested or provide both funding and technical support as a cooperative agreement.

China ‘could reach herd immunity against Covid-19 by end of year’

China adopted an “elimination strategy” to cope with Covid-19, relying on tough non-pharmaceutical measures to keep the virus outside its national borders while trying to find the sources of local outbreaks and eliminating community spread.

National Health Commission official Zheng Zhongwei said earlier that China would not relax Covid-19 control measures until the country had reached “a certain level” of vaccine coverage and that vaccination could guarantee the effectiveness of adjusting control measures.

The studies will prioritise investigating how vaccination with Chinese products might affect the Covid-19 pandemic. For example, they will examine how the process affects community transmission and changes the spectrum of Covid-19 cases as well as disease severity and the impact on health care systems.

“So far, we can see that most of the vaccines have a major role in preventing severe mortality and hospitalisation, but are limited in preventing infection, which has important value for our Covid-19 prevention and control strategies. We hope that overseas sites will yield some evidence of the impact of vaccination of the whole population on the prevention and control of Covid-19 and enrich our understanding of vaccine safety on a larger scale,” An said.

The studies will also explore the effectiveness of mixing vaccines to prime immune response, whether booster shots are necessary and the optimal timing, and the duration of protection because “it is very difficult to conduct such lasting studies in China”.

The studies will also focus on vaccine effectiveness among groups that are excluded from clinical trials but need to be vaccinated, such as the elderly, adolescents and people with chronic conditions or co-morbidities.

In countries where Chinese vaccines have been used – such as Brazil, Malaysia, Bahrain and Thailand – effectiveness studies were conducted but An said there was not enough data.

Why countries still want China’s vaccines despite concerns over effectiveness

While more than 400 papers on real-world Covid-19 vaccine effectiveness studies are available, including in preprint version and not peer reviewed, only 24 papers covered Chinese vaccines and none were published in a peer-reviewed journal.

“Two out of seven Covid-19 vaccines that have been approved by World Health Organization emergency use listing are Chinese vaccines but the quantity of papers is so small,” An said.

“We hope for more studies on Chinese vaccines but we are facing this challenge of not being able to study them in China because local outbreaks are always quickly contained.”

Researchers were able to study how vaccination protects against the Delta variant when it caused community outbreaks in Guangdong province in May and Jiangsu province in July, but the outbreaks were contained within a month and the size of the study was limited.

Other variants of concern such as Mu that had not been detected in China could not be studied either, An added.

For vaccine developers such studies were necessary for the products to be widely used around the world, and serve as the “core key evidence” if they were to be approved by the WHO for emergency-use listing (EUL), prequalification or eventual full approval, An added.

Two home-grown vaccines, Sinovac and Sinopharm, have been approved by the WHO for emergency use, but as part of the EUL process, they must commit to continuing to generate data to enable full licensing and WHO prequalification of the vaccine. Three more Chinese vaccines – developed by CanSino Biologics, Anhui Zhifei Longcom and a Wuhan subsidiary of Sinopharm respectively – are in the process of applying for EUL approval from WHO.

China provided nearly 1 billion doses of Covid-19 vaccines to 105 countries and four international organisations and aimed to provide 2 billion this year.

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