When asked on CBS Evening News when the 'general public' can get vaccinated against COVID-19, Dr Fauci predicted there will be enough doses by April.
'That will likely be within the first quarter of 2021 by let's say April of 2021'.
He noted that that prediction assumed approval processes go smoothly for all vaccines in development in the US.
Currently, trials for Johnson & Johnson's, AstraZeneca's and Inovio's shots are all paused for safety concerns.
Top US infectious disease expert Dr Anthony Fauci believes the average American could realistically have a coronavirus vaccine by April, he said Wednesday.
'That will likely be within the first quarter of 2021 by let's say April of 2021,' Dr Fauci told CBS Evening News.
His predicted timeline does not fit with President Trump's. At campaign rallies this week - after his own bout with coronavirus - Trump promised his supporters that that vaccines are coming 'very soon.'
Dr Fauci added that the public getting access to COVID-19 vaccines by April was the best case scenario.
'That would be predicated by the fact that all of the vaccines that are in clinical trials have proven to be safe and effective,' he added.
As of now, trials for three experimental vaccines - made by AstraZeneca, Johnson & Johnson and Inovio - are paused due to potential safety issues, although experts say these holds are not necessarily cause for concern.
Dr Fauci's comments also underscored the importance that not just one, but all vaccine candidates succeed.
The goal of Operation Warp Speed, the White House's program to fund and speed the development of coronavirus vaccines, is to amass 300 million doses of vaccines, with the first doses available by January 2021.
Warp Speed has contracted with several vaccine makers - including leaders Moderna, Pfizer, AstraZeneca and Johnson & Johnson for hundreds of millions of doses of each of their shots.
But top health officials, including Department of Health and Human Services (HHS) Secretary Alex Azar have made more modest estimates of 100 million doses by year end, 'pending FDA authorizations, he said in congressional testimony.
Moderna has said it can make 20 million doses by year-end.
Pfizer, a giant in the pharmaceutical world, believes it can make 100 million doses by year-end.
Their efforts would be complicated by stockpiles of vaccines made by equally enormous Johnson & Johnson and AstraZeneca, the latter of which is producing a vaccine designed by Oxford University.
But trials for both AstraZeneca's and Johnson & Johnson's vaccines are now on hold, due to safety concerns.
FDA rule changes make it effectively impossible for even the farthest-ahead trials to have enough data to submit to regulators for emergency approval before the November 3 election - the date President Trump had eagerly pushed to have a vaccine by.
Even if the paused trials resume quickly and all goes smoothly, the first doses of vaccines will not go out to everyone in the US simultaneously.
Currently, most experts advising the Centers for Disease Control and Prevention (CDC) recommend the shots go to healthcare and front-line workers first, and that people with underlying conditions like heart disease and diabetes be vaccinated early.
Older people, who account for the vast majority of COVID-19 deaths will be toward the front of the line for vaccines as well.
Healthy young adults will have to wait until at-risk groups have all been inoculated before it will be their turn for COVID-19 vaccination.
The CDC said Wednesday that it may not recommend children get vaccinated in the the first wave of shot roll-outs at all.
And the World Health Organization said on Wednesday that it may be as late as 2022 before young, healthy people can get their vaccines.
Despite the delays, Fauci's prediction that the general population could be vaccinated by the end of Q1 is still in line with his comments to Congress last month that the US could have enough coronavirus vaccine doses for all Americans by April.