HONG KONG and BEIJING – China’s Sinovac Biotech Ltd. delayed releasing trial data from its Coronavac COVID-19 vaccine while the National Medical Products Administration (NMPA) accepted an NDA from China National Biotec Group (CNBG) for its own vaccine, BBIBP-CorV.

On Dec. 24, the NMPA accepted an NDA for BBIBP-CorV, a traditional inactivated whole virus vaccine candidate developed by CNBG’s Beijing Institute of Biological Product. CNBG is part of China National Pharmaceutical Group (Sinopharm). Just three days earlier, the NMPA had announced that a 60-day review would be waved for COVID-19 vaccines and would, instead, be approved and marketed right away.

The first COVID-19 vaccines are now expected to hit the market by the end of 2020 or in January. CNBG’s vaccine was approved in the United Arab Emirates and Bahrain earlier this month.

Even as CNBG’s vaccine gets closer to the market, it could be some weeks yet before Sinovac’s Coronavac, seen as one of the leading products in China, gets to the finish line. 

Coronavac, an inactivated whole virus vaccine based on a strain of SARS-CoV-2 isolated from a patient in China, is being tested in at least four trials outside China, including a large phase III in Brazil. On Dec. 23, Brazil’s Butantan Institute said Coronavac had surpassed 50% efficacy but did not release any further details, saying Sinovac had asked for another 15 days to analyze trial data from Brazil and from other sites. Sinovac is running a trial in Indonesia and another case-driven, randomized, double-blinded and placebo-controlled trial in Turkey. In Indonesia, another randomized, observer-blind, placebo-controlled trial with an estimated enrollment of about 1,620 patients is being run by PT Bio Farma. Sinovac is also testing the vaccine in Chile in a randomized, double-blined, placebo-controlled study of about 2,300 participants.

Butantan, a government-backed research institute, is running the Brazil trial involving 13,000 participants and will be in charge of domestic manufacturing and distribution. Butantan said the delay was not linked to efficacy.  

“The results of phase III reveal that we have reached a number of effectiveness above what is necessary,” Dimas Covas, director of the Butantan Institute told BioWorld. “Now, the idea is to make this data compatible with the results of clinical tests of the same vaccine that are being carried out in other countries.”

The institute said the phase III trials have shown that the vaccine is effective, “exceeding the WHO-required rate,” but did not release specific details.

Brazil continues to lay the groundwork to distribute Coronavac widely once it is approved. Another batch of about 500,000 doses of Coronavac arrived in Sao Paulo on Dec. 28 from China. Butantan expects to receive another 1.5 million doses on Dec. 30.

“We reached the end of 2020 with approximately 11 million vaccines on national soil, guaranteeing Butantan's commitment to making the immunizing agent feasible for the Brazilian population so that, as soon as [the vaccine is] registered by Anvisa, vaccination can start," said Covas.

“It was good of Sinovac to delay the announcement until all of the data in all of their trials is compiled and analyzed,” Jerome Kim, the South Korea-based director general at the International Vaccine Institute (IVI), told BioWorld. “You would want nothing less from an agency charged by the government with ensuring the safety and efficacy of vaccine products for use in its citizens.”

Doubts about Chinese vaccines

The delay in releasing data could sow doubts about the quality of Chinese vaccines, particularly in places like Brazil where the issue has been politicized. Those doubts were exacerbated in November when Anvisa, Brazil’s regulator, briefly suspended the Coronavac trials.

Brazil’s President Jair Bolsonaro also publicly expressed doubts about the Chinese vaccine during a Facebook address on Dec. 24, when he said the government would not take any responsibility for the vaccine.

Even with the limited data available, some vaccine experts are confident about Chinese vaccines.

Although Coronavac has yet to receive approval from any regulatory authority, Brazilian regulators visited Sinovac's manufacturing facilities in China and gave it a GMP certification, paving way for a marketing approval.

“These vaccines [by Sinovac and Sinopharm] are all quite promising,” He Gongxin, the former chief representative at the Shanghai office of Gilead Sciences Inc., told BioWorld. “The key will be the results after mass vaccinations and how long efficacy lasts.”

For the time being, Coronavac is the only vaccine that will be immediately available in Brazil, but widespread distribution will not be possible until regulatory approval. 

Officials from Brazil’s state of Sao Paulo said that the vaccine had not reached the 90% efficacy threshold and that there were more than 170 COVID-19 cases among some 13,000 trial participants, but did not break that down among participants that received the vaccine or a placebo.

Where’s the data?

The difference in the availability of data from Chinese vaccine developers like Sinovac and North American or European developers like Pfizer Inc. and Biontech SE has been stark. Pfizer/Biontech were relatively quick to release data from a trial involving 36,523 people showing that its vaccine was 95% effective. Sinovac has, to date, kept late-stage trial data under wraps.

Nevertheless, results from a phase I/II trial of Coronavac released in November in The Lancet suggested Coronavac generated antibody responses within 28 days of a first immunization after administering two doses 14 days apart. The randomized, double-blind, placebo-controlled tested the safety, tolerability, and immunogenicity of the vaccine. The results showed that Coronavac was well tolerated and induced humoral responses against the SARS-CoV-2 virus, which supported the approval of the vaccine’s emergency use of in China and in three phase III studies.