Zombie Spring nbcnews.com

Secretary of Health and Human Services Alex Azar predicted Tuesday that there would be enough Covid-19 vaccine for general public vaccination campaigns by spring 2021.

In an appearance on the TODAY show, Azar outlined what he said would be the distribution schedule for Pfizer's and other companies' experimental vaccines, none of which are approved, but Pfizer said Monday its vaccine is over 90 percent effective at preventing coronavirus infection.

Azar said the pharmaceutical giant is ramping up to deliver 20 million doses of its coronavirus vaccine monthly by the end of November.