Initial data shows mRNA vaccines from Moderna and Pfizer-BioNTech retain most of their effectiveness for at least six months though further protection remains to be determined.

Walmart pharmacy technician Amber McGowan, left, gives James Williams the Pfizer vaccination at the Mississippi Urban League Building, located at the Jackson Medical Mall in Jackson, Mississippi, April 15, 2021.
Walmart pharmacy technician Amber McGowan, left, gives James Williams the Pfizer vaccination at the Mississippi Urban League Building, located at the Jackson Medical Mall in Jackson, Mississippi, April 15, 2021. (AP)

The head of Pfizer has said in an interview that people will "likely" need a third dose of his company's Covid-19 shot within six to 12 months of vaccination, while elsewhere defending the relatively higher cost of the jab.

CEO Albert Bourla also said that annual vaccinations against the coronavirus may well 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 that there will be likely a need for a third dose, somewhere between six and 12 months and then from there, there will be an annual revaccination, but all of that needs to be confirmed," he said, adding that variants will play a "key role".

"It is extremely important to suppress the pool of people that can be susceptible to the virus," he said.

Researchers currently don't know how long vaccines provide protection against the coronavirus.

Pfizer published a study earlier this month that said its jab is more than 91 percent effective at protecting against the coronavirus, and more than 95 percent effective against severe cases of Covid-19 up to six months after the second dose.

But researchers say more data is needed to determine whether protection lasts after six months.

Bourla also Thursday defended the price of his company's vaccine, saying they are saving lives and will not be sold to poor countries for a profit.

READ MORE: Can you mix and match Covid-19 vaccines?

Rising prices

"Vaccines are very expensive," Bourla said in an interview with several European news outlets.

"They save human lives, they allow economies to reopen, but we sell them at the price of a meal," he was quoted as saying.

According to data released several months ago by a member of the Belgian government, the Pfizer coronavirus jab has been the most expensive one for the European Union, along with the vaccine by Moderna.

Bulgarian Prime Minister Boyko Borissov explained earlier this week that the vaccine's price was rising as sales were being negotiated, costing as much as 19.50 euros ($23), up from 12 euros.

The prices are in sharp contrast to the vaccine produced by British-Swedish drugmaker AstraZeneca, which vowed not to make a profit on its product during the pandemic and sold it to the EU for less than two euros a unit.

Bourla did not confirm the price of the Pfizer vaccine but admitted that it was sold at a higher price to developed countries like those in the EU or the United States.

"In middle-income countries, we sell it for half the price," he said.

"In poorer countries, including in Africa, we sell it at cost."

The Pfizer vaccine, developed by the US-based company in partnership with German firm BioNTech, currently plays a leading role in American and European vaccination campaigns.

The pharmaceutical giant announced in February that it was testing a third dose of its vaccine to better combat the emerging variants.

And Bourla said Thursday the company was working on a new formula that would allow the vaccine to be stored for four to six months at a normal temperature, rather than the minus 70 degrees Celsius (minus 94 Fahrenheit) or below currently required.

READ MORE: Scientists say universal vaccine needed to fight off future coronaviruses

US readies for booster

The United States is preparing for the possibility that a booster shot will be needed between nine to 12 months after people are initially vaccinated against Covid-19, a White House official said on Thursday.

While the duration of immunity after vaccination is being studied, booster vaccines could be needed, David Kessler, chief science officer for President Joe Biden's Covid-19 response task force told a congressional committee meeting.

"The current thinking is those who are more vulnerable will have to go first," he said.

"We don't know everything at this moment," he told the House Coronavirus Crisis Subcommittee. "We are studying the durability of the antibody response.

"It seems strong but there is some waning of that and no doubt the variants challenge" that, he said.

"I think for planning purposes, planning purposes only, I think we should expect that we may have to boost."

The United States is also tracking infections in people who have been fully vaccinated, Rochelle Walensky, director of the US Centers of Disease Control and Prevention told the House subcommittee hearing.

Of 77 million people vaccinated in the United States, there have been 5,800 such breakthrough infections, Walensky said, including 396 people who required hospitalisation and 74 who died.

Walensky said some of these infections have occurred because the vaccinated person did not mount a strong immune response. But the concern is that in some cases, they are occurring in people infected by more contagious virus variants.

READ MORE: US CDC: Vaccinated people need not quarantine post-Covid-19 exposure

Source: TRTWorld and agencies