Pfizer's chairman says it's not clear whether people who are vaccinated can still spread COVID-19

• Pfizer's CEO said it's not clear if the company's coronavirus vaccine will no longer be able to spread the virus to other people.
• Albert Bourla told NBC's "Dateline": "I think this is something that needs to be examined. We are not certain about that right now with what we know."
• Independent researchers have already made it clear that the trials used to test the vaccine did not examine its effects on transmission.
• The US could approve Pfizer's vaccine on December 10. It is already approved in the UK.

The chairman of Pfizer said it's not clear whether people who have taken the company's coronavirus vaccine will still be able to spread the virus to other people.

Albert Bourla told NBC's "Dateline" that more studies had to be done into whether someone who had been vaccines could still transmit the coronavirus.

Host Lester Holt asked Bourla: "Even though I've had the protection, am I still able to transmit it to other people?"

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

—Dateline NBC (@DatelineNBC) December 3, 2020

The vaccine was developed jointly by Pfizer and the smaller firm BioNTech.

Researchers who were not involved in the vaccine's development already highlighted how the company's trials - and those run by other companies producing coronavirus vaccines - did not assess whether the vaccine affects how the virus spreads.

It raises the possibility that vaccinated people could still pass the disease to others.

The answer to the question will have a profound effect on how authorities deal with the pandemic after a vaccine arrives.

As Business Insider's Andrew Dunn previously reported, top researchers are pitching additional studies on the topic to Pfizer and Moderna.

Pfizer and BioNTech announced last month that their vaccine was 95% effective at preventing COVID-19.

The US Food and Drug Administration (FDA ) is assembling independent experts on December 10 to evaluate the vaccine, and a decision on whether the US is authorizing the vaccine could come the same day.

The UK has already approved Pfizer and BioNTech's vaccine for use.

The top scientist advising Operation Warp Speed, the US government vaccine rollout program, predicted this week that more than 100 million Americans would be vaccinated against COVID-19 within the next 100 days.