Brazil’s health regulator said on Monday (9 November) that it had suspended clinical trials of a China-made coVID-19 vaccine because of an “adverse reaction” in a volunteer, dealing a blow to one of the most advanced vaccine candidates.
The setback for a CoronaVac vaccine being developed by Sinovac Biotech came on the same day that Pfizer, the US giant, said its vaccine candidate had shown 90 per cent efficacy, sending global markets soaring and raising hopes the outbreak was over.
Sinovac, Pfizer and Oxford are all in phase III trials, the final testing phase before regulatory approval.
Anvisa, the Brazilian regulator, said in a statement that it had “ruled to suspend clinical trials of the coronavirus vaccine” after a severe adverse reaction on October 29.
The company said it could not specify what had happened because of privacy rules, but such incidents included deaths, potentially fatal side effects, severe disabilities, hospitalizations, birth defects and other “major clinical events.”
Central Brasileira DE Noticias, a Brazilian CBN radio station, said on 9 November that the suspension was due to the death of volunteers, although this has not been confirmed by Anvisa. According to information obtained by CBN, the volunteers who died were not themselves infected with coronavirus, and the cause of their death was not known.
However, the Instituto Butantan in Sao Paulo, the public health centre co-ordinating Brazil’s vaccine trials, said it was “surprised” by the decision.
The institute “is investigating in detail what happened” and is “providing the necessary clarification, with the permission of Brazilian regulators, of any adverse events that may have occurred in clinical trials,” it said.
In response to the suspension of vaccine testing by Brazilian health authorities, sinovac insiders said that they were “still in the process of communicating”.
The CoronaVac vaccine is involved in a messy political battle in Brazil, and its most visible supporter is Joao Doria, the governor of Sao Paulo state and the chief rival of Jair Bolsonaro, the far-right President.
The Sao Paulo state government said in a statement that it “regrettably learned of the decision from the media rather than directly from Anvisa,” the regulator, and was waiting with the Butantian Institute in Sao Paulo for more information “on the real reasons for the suspension.”
Bolsonaro calls CoronaVac a vaccine from “another country” and is pushing for a rival vaccine developed by Oxford University and Astrazeneca.
Last month, Mr Bolsonaro vetoed his health minister’s plan to buy 46m doses of CoronaVac, saying that “the Brazilian people will not be anyone’s guinea pigs” and calling it “The Chinese vaccine of Joao Doria”.
Doria announced earlier on Monday that the first 120,000 doses of coronavirus would arrive in Sao Paulo on November 20.
His state reached an agreement with Sinovac to buy a total of 46 million doses of the vaccine, of which 6 million are produced in China and the rest in Sao Paulo. Last week, Sao Paulo broke ground on a factory to make vaccines domestically.
The Folha DE Sao Paulo newspaper quoted an unnamed Doria ally as saying: “State officials are worried that Bolsonaro will use the technology to decide to delay the timetable for the vaccine for political reasons.”
Anvisa, the regulator, told AFP it had no comment beyond its statement announcing the moratorium. Stopping the tests is standard procedure in such cases, the statement said.
Bolsonaro has been criticized for his handling of the outbreak, including playing down the virus, opposing lockdown measures and promoting hydroxychloroquine despite studies showing it was ineffective against COVID-19.