CAJICA, Colombia – Authorities in Brazil released new efficacy data for Sinovac Biotech Ltd.’s COVID-19 vaccine Coronavac that surprised on the downside, suggesting the vaccine could be much less effective than initially indicated for preventing symptomatic infections. Immediately after the press conference, an aggressive campaign was launched on social media to promote vaccination and reassure the public even though Brazil's Butantan Institute, which will manufacture and distribute it, still needs to file more than a third of the documents needed, according to Anvisa. Anvisa is expected to meet to make a decision on the emergency approval on Sunday, Jan. 17.

Esper Kallas, a professor at the Department of Infectious and Parasitic Diseases at the School of Medicine of the University of Sao Paulo, said during a Jan. 12 press conference that Sinovac has three levels of assessment: 50.4% efficacy against very mild disease (a symptom with a positive PCR test), 77.9% against mild disease leading to a person seeking medical assistance, and finally 100% for severe disease. It was not entirely clear why the lower results were not included in the first data release.

On Jan. 7, Butantan released partial efficacy data and said Coronavac was 78% effective against the virus. At the time, the lower efficacy data against the mildest cases was not disclosed.

The expanded data, based on results from 9,242 participants in a phase III trial for the vaccine conducted in Brazil, were released ahead of the submission of an application to register Coronavac through an emergency pathway designed by Brazil’s main medical regulator, Anvisa.

“If we have a vaccine that has about 50% of effectiveness, we know that the most urgent thing now is a robust advertising campaign to inform people about the safety and effectiveness of this vaccine,” said Natalia Pasternak, president of the Institute of the Question of Science (IQC), who also participated in the two-hour press conference.

“The effectiveness of this vaccine in the real world will depend on how many people get vaccinated, so our bigger goal now should be to campaign for vaccination, by calling people to vaccinate, because only then we will see a real result in society,” Pasternak said.

Butantan already has supplies in hand to manufacture around 11 million doses of Coronavac and the government of Sao Paulo has distributed 75 million syringes in preparation of a vaccination campaign.

“The Butantan vaccine was able to reduce the need for hospitalization and the most severe forms of COVID-19 by 100%. It also reduced by 78% the mild cases and more than 50% of the very mild cases, when the symptoms are practically nonexistent,” said Doria. “It is what we need immediately to save lives.”

Butantan insisted that the vaccine is very safe and that the safety and efficacy was shown among trial participants with high exposure to COVID-19. Covas insisted that the phase III trials for Coronavac were among the most stringent in the world given the risk and exposure to the virus among the 13,000 health care workers that took part.

“It is a group of professionals whose infection incidence was higher than 20%. The largest incidence among all the populations at risk,” he said. “It is a population that not only is subjected to a heavy viral load, but it is also the population that challenged the vaccine more intensely. The test for this vaccine in this population is the hardest test that a vaccine may face. None of the other vaccines has been tested in populations resembling the incidence above 20%.”

Still, Tuesday's announcement of that the overall effectiveness of the vaccine candidate was lower than originally announced generated controversy in Brazil around Coronavac and not for the first time.

In December, Butantan delayed the release of the phase III results, saying that Sinovac wanted more time to analyze them and align them with results from phase III trials taking place in different countries.

Pressure to approve

“It is very likely that, if Anvisa refuses to approve the vaccine, Supreme Court judges will demand explanations,” Igor Patrick, director of communications at Observa China, an independent network of Portuguese-speaking sinologists, told BioWorld. “The second option is to trigger a section of the COVID Law, sanctioned by President Jair Bolsonaro himself in March. This law guarantees automatic vaccine approval in Brazil if the same vaccine is authorized in the U.S, EU, Japan or China. Governor Doria has already indicated that he will use this law to guarantee vaccination in Sao Paulo, if needed.”

Anvisa is also expected to consider on Sunday whether to grant an approval to Astrazeneca plc’s AZD-1222 vaccine. The Oswaldo Cruz Foundation (Fiocruz) is applying for the approval and Anvisa has said it has received 85.6% of the required documents.

“The date represents the penultimate day of the period established by the agency itself for the analysis of requests. Therefore, it is necessary to deliver, in a timely manner for analysis, the missing and complementary documents,” said Anvisa.