Dr. Anthony Fauci, the top United States infectious diseases expert, said an approved coronavirus vaccine could end up being effective only 50 to 60 percent of the time, meaning public health measures will still be needed to keep the pandemic under control.

Fauci said in a webinar hosted by Brown University that they still don’t know the efficacy of the vaccine.

“We don’t know yet what the efficacy might be. We don’t know if it will be 50 percent or 60 percent. I’d like it to be 75 percent or more,” Fauci said.

“But the chances of it is 98 percent effective is not great, which means you must never abandon the public health approach,” Fauci added.

The novel coronavirus has infected nearly five million people in the US and killed more than 160,000.