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Dr. Rick Bright, the ousted federal official who was previously leading coronavirus vaccine development, told Congress on Thursday a COVID-19 vaccine may take longer to develop than 18 months.

Bright testified on Capitol Hill after filing a whistleblower complaint alleging his recent ouster was retaliatory, and he was asked when he thinks there could be a COVID-19 vaccine. Experts like Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, have cited a possible timeline of between 12 and 18 months. Bright, however, wasn't so sure.

"A lot of optimism is swirling around a 12 to 18 month timeframe, if everything goes perfectly," Bright said. "We've never seen everything go perfectly. ... I still think 12 to 18 months is an aggressive schedule, and I think it's going to take longer than that to do so."

Bright also expressed concern about rushing a vaccine and cutting out steps so that we don't have a "full assessment" of its safety. The 12 to 18 month timeline is from when a given manufacturer first started developing a vaccine rather than from right now, and it refers to how long until a vaccine can be used on an emergency basis rather than until it's approved by the FDA, Bright explained.

President Trump in recent weeks has expressed confidence there will be a coronavirus vaccine by the end of 2020. Testifying before Congress earlier this week, Fauci said it's "more likely than not" there will be a vaccine within the next one to two years, and he said earlier this month having a vaccine ready by January 2021 is potentially "doable," assuming "things fall in the right place." Brendan Morrow