are expressing skepticism about Russian President Valdimir Putin's claim that his country was the first to develop a safe and effective coronavirus vaccine.

National Institute of Allergy and Infectious Diseases, said Tuesday he hopes Moscow has "actually definitively proven that the vaccine is safe and effective.

“I hope that the Russians have actually definitively proven that the vaccine is safe and effective,” says Dr.

Health Secretary Alex Azar said during a visit to Taiwan Wednesday that the push to develop a COVID-19 vaccine is "not a race to be first.".

is combining the powers of its government, economy and biopharmaceutical industry to "deliver as quickly as we can for the benefit of the United States' citizens, but also for the people of the world, safe and effective vaccines.".

He pointed out that four of the six companies under contract have reported testing results showing they produce more antibodies for the virus than people who have survived COVID-19, without severe side effects.

Azar said two companies' vaccine candidates have entered the third phase of trials while the Russian vaccine is just now embarking on that stage with no information having been disclosed.

process should enable the production of a "gold-standard, safe and effective vaccine" available in the tens of millions of doses by the end of the year

But Russian Health Minister Mikhail said Wednesday that accusations that Russia's vaccine is unsafe are baseless and stem from competition, Russia's Interfax news agency reported, according to the Reuters news service.