Bourla added that he thinks people may need to be immunised against coronavirus annually.
Recently, updated from clinical trials showed that the Pfizer vaccine was more than 90 effective at preventing COVID-19 six months after the second dose.
Findings included a 91.3% vaccine efficacy against COVID-19, and over 95% efficacy against severe disease.
The head of the Pfizer pharmaceutical company has warned that people will probably need a third dose of his laboratory's Covid-19 shot within six to 12 months of vaccination, adding that annual booster shots may also be required.
"We need to see what would be the sequence, and for how often we need to do that, that remains to be seen", Bourla told CNBC in an interview recorded on April 1.
"A likely scenario is there will be likely a need for a third dose somewhere between six and 12 months and then from there would be an annual revaccination", he said at the event, as cited by The Hill.
"There are vaccines that's like polio that one dose is enough, there are vaccines like pneumococcal vaccine that one dose is enough for adults and there are vaccines like flu that you need every year", Bourla said.
The Ministry, in a video posted on its social media platform video, conveyed the message that getting vaccinated against COVID-19 will protect the health of individuals and other members of the community.
Multiple victims at high school shooting in Tennessee
Police said they responded to the school around 3:15 p.m. and when they encountered a male with a gun, shots were fired. One person was detained for further investigation, officials said. "This wasn't a school shooting .
Bourla also highlighted the importance of reducing the number of potential virus carriers and expressed optimism that vaccines will be an important tool in the battle against the extremely contagious coronavirus variants.
"And again, the variants will play a key role".
The over-80s, clinically extremely vulnerable, health and social care staff and care home workers were the first to be vaccinated against coronavirus in December and the first weeks of this year.
"We don't know everything at this moment", he told the House Coronavirus Crisis Subcommittee.
Ms Walensky said some of these infections have occurred because the vaccinated person did not mount a strong immune response.
About 144 volunteers will be given the third dose, mostly those who participated in the vaccine's early-stage U.S. testing a year ago.
In the United States, health officials are already preparing for booster doses to be issued between nine and twelve months after people are fully vaccinated.
"I think for planning purposes, planning purposes only, I think we should expect that we may have to boost".