WASHINGTON DC: Speaking to reporters on Sunday, Dr. Anthony Fauci said he would not hesitate to be inoculated with the newly developed one-shot Johnson & Johnson COVID-19 vaccine.

Fauci is the well-known director of the U.S. National Institute of Allergy and Infectious Diseases, an agency of the National Institute of Health.

He encouraged all Americans to be inoculated with any of the three available vaccines.

"All three of them are really quite good, and people should take the one that's most available to them. If you go to a place and you have J&J, and that's the one that's available now, I would take it," Fauci said on NBC's Meet the Press.

On Saturday, the U.S. government approved the use of Johnson & Johnson's single-dose COVID-19 vaccine. The Johnson & Johnson vaccine is now the third to be available in the United States, along with Pfizer/BioNTech and Moderna vaccines, which require two doses and need to be shipped frozen.

The Johnson & Johnson vaccine requires no special refrigeration for shipping or storage.

While the Pfizer and Moderna vaccines initially were seen as more effective than Johnson & Johnson's vaccine, Fauci said new testing is underway and he suggested the results would be more promising for Johnson & Johnson.

He noted that Johnson & Johnson's vaccine was tested while new variants of the virus were circulating, which might have altered the test results.

Experts note that the Johnson & Johnson vaccine offers the U.S. government an important third option for immunizing large segments of the population.

Thus far, some 14 percent of Americans have received at least one dose, according to government officials.

President Joe Biden has said he expects all Americans to be vaccinated by the end of July.