Pfizer’s Chief Executive Officer Albert Bourla said on Friday that the drug-maker expects to be able to double the weekly number of doses of its COVID-19 vaccine it will supply to the United States in the next few weeks.

Bourla, speaking after US President Joe Biden toured his company’s vaccine manufacturing facility in Michigan, said Pfizer was currently sending out an average of 5 million doses per week and expects to “more than double that number” in coming weeks.

“We have improved our processes to double the batch size and increase yield and we have deployed more efficient lab test methods to reduce release times,” Bourla said in his remarks.

He said those measures allowed the company to reduce the time it takes to make the vaccine from 110 days to 60 days.

Bourla said that by February 17, Pfizer had supplied the United States with 40 million doses of the COVID-19 vaccine it developed with German partner BioNTech SE.

The company has agreed to supply 300 million doses to the United States by the end of July.

Bourla said Biden had challenged the company to beat that target, and it would look for ways to improve its production.