The resignation of Congo’s health minister in the midst of the country’s worst Ebola outbreak could clear the way for a second experimental vaccine to be deployed. But the new shot would likely take months to win the trust of frightened locals and show results, health officials say, according to Reuters.

Oly Ilunga, who opposed using the vaccine developed by U.S. pharmaceutical giant Johnson & Johnson, resigned as minister on Monday after being bumped off the Ebola response team.

The World Health Organization recommended the two-dose shot to complement a vaccine by U.S. drugmaker Merck, which has proved highly protective but is in relatively short supply.

Proponents, including medical charity Medecins Sans Frontieres (Doctors Without Borders) and the Wellcome Trust, said the new vaccine could be deployed to areas not yet affected by Ebola to create a firewall against the virus, which the WHO declared an international health emergency last week.

But Ilunga said the J&J vaccine had not been proven effective and could confuse people in eastern Democratic Republic of Congo, where wild rumours are hampering the response.

“Congolese have the right to have the gold standard, the best vaccine,” he told Reuters on Thursday, in his first public comments since resigning. “They don’t need to be the subject of experimentation.”

“You can’t have a group of promoters, producers of the vaccine (and) university researchers wanting to introduce the vaccine without contacting the health authorities,” he said, without elaborating further.