Pharmaceutical company Pfizer believes their COVID-19 vaccine may be finished by the end of October. They’re already manufacturing the vaccine, so they’ll be ready to go if the vaccine works and the government approves.

Pfizer head Albert Bourla told CBS’s “Face the Nation” that their studies and trials will wrap up by Halloween. “We started already manufacturing and we have already manufactured hundreds of thousands of doses, so just in case we have a good study readout, conclusive and FDA, plus the advisory committee feels comfortable that we will be ready," he said.

READ: Promising Coronavirus Vaccine Resumes Trials After Brief Pause

Still, they aren’t done studying the vaccine yet. The Phase Three trial is expanding from 30,000 participants to 44,000. Bourla says that they’ll hopefully have results at the end of next month. “We have a good chance that we will know if the product works by the end of October,” he said.

Pfizer did not accept federal funding for their coronavirus vaccine development. They will eat the cost of the “hundreds of thousands of doses” if the study doesn’t turn out as they hope.

Bourla believes rejecting federal funding gives scientists more freedom.

“I wanted to liberate our scientists from any bureaucracy,” he said. “When you get money from someone that always comes with strings. They want to see how we are going to progress, what type of moves you are going to do. They want reports. I didn't want to have any of that. I wanted them — basically, I gave them an open checkbook so that they can worry only about scientific challenges, not anything else. And also, I wanted to keep Pfizer out of politics.”

Still, Bourla couldn't predict when the vaccine would be on the market. Other professionals expect a vaccine to be available in 2021, likely in the first half of the year.

Until a vaccine is ready, the CDC continues to recommend wearing masks and social distancing to prevent the spread of COVID-19.