Pfizer CEO: 'Not certain' whether someone can transmit COVID-19 after vaccination

With three promising vaccines for COVID-19 in the pipeline, there's still uncertainty about how effective they will be.

Albert Bourla, chairman and CEO of Pfizer Pharmaceutical – which has applied to the Food and Drug Administration for emergency use authorization for its vaccine – sat down with CBS's Lester Holt on "Dateline NBC" for an interview that will air Thursday night.

Holt said: "And then what about the question, Albert, of even though I’ve had the protection, am I still able to transmit it to other people?" according to transcript provided by the network.

"I think this is something that needs to be examined," Bourla said. "We are not certain about that right now with what we know.”

Biotech firm Moderna on Monday said it will ask the FDA to approve its experimental COVID-19 vaccine for emergency use. Moderna said new data showed the vaccine was 94.1% effective in its late-stage clinical trial, just under Pfizer’s efficacy rate of 95%. The Moderna vaccine was developed in conjunction with the Trump administration’s Operation Warp Speed.

“We believe that our vaccine will provide a new and powerful tool that may change the course of this pandemic and help prevent severe disease, hospitalizations, and death,” Moderna CEO Stéphane Bancel said in a statement. Bancel said last week that 20 million doses will be available by the end of the year.

The FDA’s vaccine advisory committee is set to meet on December 17 to review data from the two companies.

Meanwhile, a third vaccine is also in the pipeline. AstraZeneca and Oxford University last week said their jointly created COVID-19 vaccine has proven to be up to 90% effective and the makers claim it will be easier to distribute.

Other big pharm leaders also appeared on Holt's show. 

Stephen Hoge, president of Moderna, said that while there may be side effects from any vaccine, they greatly outweigh the danger of the virus.

“Certainly when we're seeing efficacy 94%-95%, there's great reasons for hope that these vaccines are going to be very effective and beat back the virus, but there's a chance that a year from now, three years from now, we'll see that people need a booster. Not dissimilar to what we see with other vaccines," he said.