What do we know about the efficacy of Chinese vaccines so far?

On June 20, China reached a milestone administering over 1 billion Covid-19 vaccine doses, in what has been an extraordinary inoculation drive accounting for almost 40 percent of 2.5 billion jabs worldwide.

The vast majority of the vaccinations were developed by state-owned companies Sinopharm and Sinovac, with hundreds of millions of doses shipped to more than 80 countries.

Back in May 2020, Chinese President Xi Jinping kicked off Beijing’s vaccine diplomacy campaign by pledging its Covid-19 vaccines would be a “global public good,” and promising developing countries “vaccine accessibility and affordability.”

A year later, and it seems to have delivered on that promise.

But doubts over the efficacy of its vaccines are now starting to surface in countries which have relied on them.

Indonesia is struggling with its worst Covid-19 outbreak to date, after registering over 21,000 daily infections earlier in the week. Driven by new variants like the Delta strain, its latest surge has overwhelmed hospitals and burial sites.

Chinese-manufactured vaccines make up nearly 60 percent of Indonesia’s confirmed dose orders. Sinovac, which was deemed halal by the country’s top Islamic body, accounts for 90 percent of the 104 million doses it had received as of June.

However, concerns are growing after more than 350 doctors and healthcare workers have come down with infections the last month, and at least ten out of 26 doctors died despite being fully vaccinated with Sinovac.

Olivia Herlinda, policy director at the Centre for Indonesia’s Strategic Development Initiatives, told TRT World that coming to any conclusion on Sinovac’s effectiveness is difficult given the vaccination rate is still low, and those who have gotten Sinovac shots are mostly health workers and a low proportion of under 60s.

The fact of the matter is, like many other developing countries, Indonesian health authorities know that only China can supply the necessary doses that will allow it to inoculate 70 percent of the population, and achieve herd immunity within the year.

For now, Herlinda said the government doesn’t have much room to maneuvre with demand growing and supply limited.

“Until we have sufficient data regarding the efficacy, we think Indonesia has very limited options but to continue using what is available now while waiting for other vaccines to arrive,” she observed.

“The government has to push forward stronger and provide more access to any vaccines we have now to the most vulnerable groups.”

Dr Pawin Numthavaj, a clinical epidemiologist at Ramathibodi hospital in Thailand, told TRT World that Thai authorities are “still considering Sinovac because it’s easier to procure”.

He said the government had recently been looking for other manufacturers’ vaccines, but that it was a little too late with lengthy production wait times. The earliest arrival would be by the end of the year.

Apart from Indonesia, the cases of Bahrain, Chile, Mongolia and the Seychelles are starting to fuel uncertainty as well.

With 50 to 68 percent of their populations fully inoculated, all four countries have been ranked among the top ten with the worst outbreaks in the past week. Each had primarily administered Sinopharm and/or Sinovac shots.

“There are many possible reasons for this, and we need detailed epidemiological investigations to understand and explain what is going on otherwise we are just guessing,” Dr Fiona Russell, epidemiologist and vaccinologist at the University of Melbourne, told TRT World.

She said it might include questions on whether cases are emerging among unvaccinated or undervaccinated people, or due to lack of vaccine effectiveness against a particular variant, or if coverage in the population and at a subnational level is low, meaning the herd immunity threshold has not been attained.

Dr Jin Dongyan, a virologist at the University of Hong Kong, said for many countries dependent on Chinese vaccines, it is turning out to be a double-edged sword.

“On one hand, the Chinese vaccines are good and have saved lives in countries where most people have no access to any other vaccine,” he told TRT World.

Even if less successful at infection prevention, there is enough evidence to prove it has helped prevent severe cases and deaths, Dongyan added.

But when comparing the efficacy of different vaccines, the Chinese options come up short.

“It is true that the Chinese vaccines are much less effective in preventing infection or transmission when compared to Pfizer and Moderna. There is no doubt about that,” Dongyan argues.

“Breakthrough infections in fully vaccinated individuals with Pfizer or Moderna in Israel and the US are much rarer. The disease patterns are very different.”

Dr Bulent Sekerel, Director of Hacettepe University’s Faculty of Medicine, agrees. He told TRT World that emerging data shows inactivated vaccines like Sinovac and Sinopharm are less effective compared with its vector (AstraZeneca and Sputnik) and mRNA (Pfizer and Moderna) counterparts.

Sekerel said the data on Chinese vaccines for Turkey, which is using Pfizer and Sinovac for its vaccination drive, has not been shared with the public nor health experts as of yet.

He also highlighted the scientific data for Chinese vaccines is presently “scarce” and “less reliable”.

That Chinese vaccine manufacturers don’t have the same level of transparency as Western manufacturers, combined with an absence of peer-reviewed publications, has made it hard for policymakers to adequately evaluate them.

Sinopharm and Sinovac did not respond to TRT World’s request for comment.

In clinical trials, Sinopharm efficacy in preventing symptomatic infection was a combined 78 percent in Bahrain, Egypt, Jordan and the UAE; Sinovac’s was 51 percent in Brazil, 67 percent in Chile, 65 percent in Indonesia, and 84 percent in Turkey.

Both Pfizer and Moderna efficacy rates were over 90 percent.

For efficacy against severe outcomes like hospitalisation, Sinovac registered 100 percent in Brazil and Turkey, and 85 percent in Chile.

Sinopharm registered a 79 percent efficacy against hospitalisation.

Although non-peer reviewed, the Uruguayan government released a study last month showing Sinovac reduced infections by 61 percent compared to 78 percent for Pfizer, while lowering hospitalisations by 92 percent and deaths by 95 percent.

The UAE, which achieved high inoculation coverage early on largely due to Sinopharm, has also experienced a recent spike in infections. Along with Bahrain, the UAE announced last month it would be offering a Pfizer booster dose six months after two Sinopharm doses.

A Pfizer booster is potentially a good idea, says Dongyan. Interim data from some trials support the safety and efficacy of a mix-and-match approach, including an ongoing study in Hong Kong, he adds.

“In principle, the risk should be minimal or very low. It is similar to vaccinating people who have been infected with SARS-CoV-2 with one dose of Pfizer.”

And because the existing immunity in previously infected people should be even stronger than in people fully vaccinated with Sinopharm, Dongyan believes the side effects of the mix-and-match approach “should not be stronger than vaccinating previously infected people.”

At the moment, the Chinese Foreign Ministry maintains there is no link between the recent outbreaks and its vaccines by citing the World Health Organization, which approved Sinovac for emergency use in June.

The ministry emphasised its vaccines are meant to target severe disease rather than transmission, and are “safe” and “have played a good role” in many countries’ epidemic prevention efforts.

One of the barriers for many developing countries acquiring mRNA vaccines is a lack of extensive cold-chain infrastructure, where doses must be stored at around -80 C. 

Sinovac and AstraZeneca on the other hand, can be kept in standard refrigerator temperatures.

As a post-pandemic world begins to take shape, countries suffering rising infections in spite of high inoculation rates could point to a scenario where many dependent on Chinese vaccines end up seeing their populations only partially protected for the foreseeable future.