(NEXSTAR) — The nation’s top infectious disease expert said he expects Johnson & Johnson to apply for an emergency use authorization for its COVID-19 one-shot vaccine this month.

“If FDA (U.S. Food and Drug Administration) determines it meets their standards, the vaccine could be available this March,” Dr. Anthony Fauci said in a Twitter Q and A on Thursday.

In results published in late January, Johnson & Johnson found its COVID-19 vaccine provides good protection against the illness.

The pharmaceutical giant’s preliminary findings suggest the single-dose option may not be as strong as Pfizer’s or Moderna’s two-dose formula and was markedly weaker against a worrisome mutated version of the virus in South Africa.

But amid a rocky start to vaccinations worldwide, that may be an acceptable trade-off to get more people inoculated faster with an easier-to-handle shot that, unlike rival vaccines that must be kept frozen, can last months in the refrigerator.

“Frankly, simple is beautiful,” said Dr. Matt Hepburn, the U.S. government’s COVID-19 vaccine response leader.

Johnson & Johnson expects to supply 100 million doses to the U.S. by June — and a billion doses globally by year’s end — but declined to say how much could be ready if the FDA gives the green light.

Defeating the scourge that has killed more than 2 million people worldwide will require vaccinating billions. The shots being rolled out in different countries so far all require two doses a few weeks apart for full protection.

In late January, regulators also cleared a third option, AstraZeneca’s vaccine, for use throughout the European Union. The decision came amid criticism that the 27-nation bloc is not moving fast enough, as well as concern that there’s not enough data to tell how well the vaccine works in older people.

Johnson & Johnson studied its one-dose option in 44,000 people in the U.S., Latin America, and South Africa. Interim results found the shot was 66% effective overall at preventing moderate to severe COVID-19 cases and much more protective — 85% — against the most serious symptoms. There were no serious side effects.

“Gambling on one dose was certainly worthwhile,” Dr. Mathai Mammen, global research chief for J&J’s Janssen Pharmaceutical unit, told The Associated Press.

The Associated Press contributed to this report.