Transcript for Pfizer reportedly faced early supply chain obstacles
And now to the massive task of rolling out the vaccine and convincing Americans and really people all over the world that it is safe. "The Wall Street journal" reporting today that Fizer had initially wanted a larger rollout, but had concerns, problems with their supply chain. Tonight, pfizer indicating this will not effect the doses expected here in the U.S. By the end of the year. ABC's gio Benitez tonight with late reporting. Reporter: Tonight, as the first doses of this life-saving vaccine are distributed, that news about pfizer's supply just S moments ago. "The Wall Street journal" reporting pfizer already dealt with early supply chain obstacles. The company slashed itial projections of doses in half this year, from 100 million to 50 million doses worldwide, after finding raw materials in production that didn't meet its standards. Pfizer stressing the problems have been fixed and will still hit its target of 20 million doses in the U.S. By the end of the month. Tonight, Dr. Anthony Fauci raising alarms, saying the uk cut corners and rushed the approval of pfizer's vaccine. They kind of ran around the corner of the marathon and joined it in the last mile. Reporter: Later apologized, and hoping the convince Americans the vaccine is safe, Fauci saying the fda is carefully reviewing the data. If we had jumped over the hurdle here quickly and inappropriately to gain an extra week or a week and a half, I think that the credibility of our regulatory process would have been damaged. Reporter: States and cities preparing for the biggest and most complicated vaccine rollout in American history. New York governor Andrew Cuomo today unpacking a sample box of pfizer's vaccine, which must be stored at minus 94 degrees, holding up a vile, each containing five doses. The box can only stay open for no more than 90 seconds. This is the weapon that is going to win the war, and that is the light at the end of the tunnel. Reporter: New York City officials say 50 hospitals have cold storage capacity to store a total of at least 1.5 million doses. The other herculean challenge? Convincing Americans to get vaccinated. We need to be very transparent with patients. Reporter: Dr. Victoria Smith participated in the pfizer trial in Louisiana. One of the reasons why I wanted to participate was to be a model of participation and have my own example be a model of the safety of the vaccine and the process. Reporter: And tonight, convincing people is a priority, but delivering a vaccine will be a challenge like never before. This is the biggest logistical challenge that the industry in general has ever faced. Reporter: ABC news getting an inside look at united's cold storage facility at Chicago's o'hare airport. The vaccines will be in refrigerated shipping containers and those can be stored in even bigger refrigerators like this. Fascinating look today from gio and he joins us live from Chicago. And gio, I wanted to get back to that reporting about pfizer's concerns about is up Bly chain issues. The company tonight stressing that those concerns have been resolved, saying pfizer will deliver the promised number of doses by the end of the year? Reporter: David, that's right. Pfizer had some early issues, but say they corrected that months ago and still on track to deliver those 20 million doses in the U.S. By the end of the year. Of course, that's if the fda gives them that green light and that could happen within just a few weeks, David. All right, gio Benitez live from Chicago tonight.
This transcript has been automatically generated and may not be 100% accurate.