Pfizer Inc announced on Tuesday, July 28, that people may need multiple doses or shots of the COVID-19 vaccine to keep the immunity levels enough to ward off novel coronavirus infection.

The company further said that other developed countries will not receive any concession or discount when it comes to the price for its coronavirus vaccine than what it charged the U.S. under a contract which was announced last week.

Pfizer and German biotech BioNTech SE signed a $2 billion deal with the U.S. government recently to provide doses for 50 million people for its COVID-19 vaccines that it is testing at the moment. The COVID-19 vaccine price for a two-dose treatment course was set at about $39.

“All the countries that are developed right now will not receive a lower price for the same volume commitment than the U.S.,” Pfizer Chief Executive Albert Bourla said during a conference call on Tuesday.

Furthermore, Pfizer executives said that people are expected to receive multiple doses over a period of time to maintain immunity against the novel coronavirus. According to them, it may be important to continue this practice over the years to achieve the desired level of herd immunity globally.

The executives further said since there is a possibility that the virus may mutate or immunity may decrease over time, there is a need for multiple shots over years for optimum protection.

On Monday, July 27, BioNTech and Pfizer announced the commencement of a large-scale study and late-stage trial of their mRNA vaccine candidate to demonstrate its efficacy.

The companies are known to be in touch with the European Union and its several member states concerning the supply of COVID-19 vaccine.

Bourla said that even though a deal with the EU would be much easier, it is still in talks with independent member states just in case no agreement is reached with the EU.

Pfizer La entrada principal de Pfizer en New York City, Agosto 31, 2003. Reuters/Jeff Christensen JC