DUBAI—A Chinese vaccine candidate showed to be 86% effective in protecting people against Covid-19 in late-stage trials, the United Arab Emirates said, a positive sign for the fight against the virus in the developing world.
However, health experts cautioned that more information was needed on the Phase 3 trials. The efficacy rate announced by authorities in the U.A.E., where the trials took place, would put the vaccine above the 50% threshold that international scientists deem necessary to protect people. Candidates developed by Moderna Inc. and jointly by Pfizer Inc. and BioNTech SE have shown to have efficacy rates of 94.5% and 95% in the final stages of testing, respectively.
The U.A.E. Health Ministry didn’t disclose how many trial participants developed Covid-19 and how many of those received a placebo or a vaccine. It also wasn’t known whether the data was peer reviewed.
The results were the first from Phase 3 trials of a Chinese Covid-19 vaccine. Nearly one million Chinese people have already received the shot, which was developed by state-owned drugmaker Sinopharm, after the government granted emergency-use authorization for it in July.
Public-health experts said that the headline figure suggested that the world had another working vaccine option, although more details were needed. Some questioned why Sinopharm hadn’t jointly presented the results.
“I think it’s great news but it’s a little unusual not to come from the study manufacturer,” said Jerome Kim, director of the International Vaccine Institute in Seoul.
Among the details that Mr. Kim said were still needed were confidence intervals that could give the public a sense of how reliable the efficacy estimate was. “There are just so many questions around the way it’s been presented.”
A U.A.E. official involved in the trial didn’t immediately respond to a request for further information. Sinopharm didn’t respond to a request for comment.
The U.A.E. said it had registered the vaccine, paving the way for its wider use, having approved it for emergency use in September. The U.A.E. government and Sinopharm haven’t disclosed the financial details of their trial partnership.
The trial began in July, involving about 31,000 volunteers and two different strains of the vaccine. The U.A.E. had previously said one-third of the trial’s participants got a placebo and the remaining two-thirds were administered one of the two strains—one developed in Beijing and another in Wuhan.
The U.A.E. said the Beijing strain was 86% effective. It wasn’t known whether an analysis was conducted on the Wuhan strain.
While some people who received the vaccine got infected, it said the shot was 100% effective in preventing moderate or severe cases of the disease. The analysis also showed 99% of participants analyzed developed antibodies against the disease.
An 86% efficacy rate makes Sinopharm’s vaccine a potential candidate for many countries in emerging markets that can’t immediately gain access to vaccines from the West. Bahrain has already approved emergency use of the vaccine, while China is also testing the candidate in Egypt, Argentina, Jordan, Peru and other countries. Countries running clinical trials generally have a head start in evaluating the vaccine for use by their own people.
While Western governments are focused on launching vaccines within their own borders, Chinese officials have talked about sharing their shot in an effort aimed in part at strengthening diplomatic ties.
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The candidate developed by Sinopharm, or China National Pharmaceuticals Group, is based on an inactivated virus, meaning that the pathogen is weakened for use on humans. It can be stored at regular refrigerator temperatures, unlike the Pfizer-BioNTech and Moderna vaccines, making it an attractive option for poorer countries lacking cold-chain infrastructure.
Hani Naja, a partner at law firm Baker McKenzie who covers health-care legislation in the U.A.E., said the health ministry doesn’t regularly green light new medicines and vaccines, as the country’s pharmaceutical manufacturers largely produce generics. But the regulator does have years of experience vetting drugs that have been approved first elsewhere, Mr. Naja said.
“It is an encouraging step,” he said. “They have been keen on making sure the vaccine is in the country as soon as possible, but also wanted to make sure it was safe.”
Sinopharm previously said that among the nearly one million Chinese people who have been vaccinated, only a few of the people experienced mild symptoms and not a single person had a serious adverse reaction.
The U.A.E. has already inoculated tens of thousands of residents with the Sinopharm vaccine since September, offering it to airport staff, teachers and government officials, including police officers, judiciary employees and 30,000 armed forces personnel. U.A.E. officials have said that none have gotten sick with Covid-19.
By contrast, Western companies sought government approvals to market their candidates to the public once clinical trials were complete.
China has three other Covid-19 experimental vaccines in late-stage trials. Brazil, which is testing Sinovac Biotech Ltd.’s CoronaVac, is expected to release efficacy results in the coming days.
Results from early clinical trials of CoronaVac showed that it induced antibodies in volunteers, although at lower levels than those seen in people who were previously infected with Covid-19.
China has had to venture overseas to conduct clinical trials on its vaccines as it has successfully controlled the coronavirus at home. Sinopharm executives have said the U.A.E. was chosen for trials due to its diverse population: Only about 10% of the country’s nearly 10 million residents are Emiratis, with the remainder largely from Asia, Europe and the U.S.
Corrections & Amplifications
An earlier version of this article misspelled Pfizer. Also, an earlier version of this article incorrectly identified Dubai’s ruler, Sheikh Mohammed bin Rashid Al-Maktoum, as crown prince in the photo caption. He is a former crown prince. (Corrected on Dec. 9, 2020)
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