Efficiencies and upgrades in the production process have helped vaccine maker Pfizer double its output of coronavirus vaccine in the past month, a spokeswoman for the company told CNN Monday.

While the company did not give any production figures to support the estimate, spokeswoman Amy Rose said Pfizer expects production time to be cut nearly in half, from 110 days to an average of 60 days for one batch of Covid-19 vaccine.

One batch is equal to between 1 million to 3 million doses, Pfizer says.

Producing the genetic material that forms the basis of the vaccine initially took 16 days, but will soon take just nine to 10 days, Rose said.

Pfizer CEO Albert Bourla said last week the company expects to deliver 200 million doses of its vaccine to the United States by the end of May.