Brazilian regulator Anvisa said in a statement that it had decided “to discontinue the clinical study of the CoronaVac vaccine after a serious adverse incident” on October 29.
He did not say where the event took place or what happened, citing privacy rules. Usually, incidents that result in suspension of trials involve death, potentially fatal side effects, severe disability, hospitalization, birth defects, or other clinically significant events.
The Butantan Institute, the medical research institute that coordinates the vaccine trials in Brazil, said it was “investigating in detail what happened” and was at the disposal of the regulatory agency. Brazilian to provide any necessary clarification on any adverse incidents that clinical trials may have presented.
The vaccines from Sinovac, Pfizer and Oxford are all in Phase 3 trials, the last stage of testing before regulatory approval.
All are being tested in Brazil, the country with the second highest death toll from the pandemic after the United States, with more than 162,000 people dying from COVID-19.
Trials of the Oxford vaccine were suspended in September after an incident involving a volunteer in the UK, but then resumed.
Dimas Covas, the head of Butantan, said the decision was linked to a death, but added that he found the regulator’s announcement strange “because it is a death unrelated to the vaccine.”
“As there are more than 10,000 volunteers at the moment, deaths can occur… It is a death that has nothing to do with the vaccine and as such, this is not the time to stop the trials, ”Covas told local television station Cultura.
Butantan is expected to hold a press conference on Tuesday at 11:00 a.m. (2:00 p.m. GMT). Sinovac did not immediately respond to requests for comment.
CoronaVac has been caught up in a messy political battle in Brazil, where its most visible supporter has been Sao Paulo Governor Joao Doria, one of the loudest opponents of Jair Bolsonaro, the country’s right-wing president.
Bolsonaro has rejected the Sinovac vaccine candidate as lacking credibility.
Last month he abolished a plan by his own health minister to purchase 46 million doses of CoronaVac, claiming the Brazilian people “would not be anyone’s guinea pig” and calling the drug “Joao Doria’s Chinese vaccine” .
Doria, who is expected to challenge Bolsonaro in the next presidential election in 2022, said her state will import and produce the vaccine and that a public immunization program in Sao Paulo could be rolled out as early as January.
The Sao Paulo state government said in a statement that it “regrets learning of the decision from the press, rather than directly from Anvisa,” and was waiting with the Butantan Institute for more information on ” the real reasons for the suspension ”.
Bolsonaro instead pushed for the vaccine developed by the University of Oxford and the pharmaceutical company AstraZeneca.
Anvisa told AFP news agency she had no comment beyond her statement announcing the stay, that a stay of trials was standard procedure in such cases.
Bolsonaro faces criticism for his handling of COVID-19, which he dismissed as a ‘little flu’ opposing lockdown measures and relentlessly promoting hydroxychloroquine despite studies showing it to be ineffective against sickness.
Sinovac, Pfizer and Oxford vaccines are all in Phase 3 trials, the final stage of testing before regulatory approval, and are all being tested in Brazil.
Sinovac’s vaccine is one of three experimental COVID-19 vaccines that China is using to inoculate hundreds of thousands of people under an emergency use program. A Chinese health official said on October 20 that no serious side effects were seen in clinical trials.
The Brazilian trial was the first of Sinovac’s large late-stage trials to start. Advanced stage trials are also being conducted in Indonesia and Turkey. Indonesian state-owned company Bio Farma said on Tuesday its Sinovac vaccine trials “were going smoothly.”
Edwin G Pringadi, a spokesperson for Bio Farma, said there were no plans to cancel clinical trials, involving around 1,600 people in the Indonesian province of West Java. Indonesia has the highest death toll from COVID-19 in Southeast Asia.