Pharmaceutical companies Pfizer and BioNTech SE said Tuesday that they are beginning trials of an experimental coronavirus vaccine known as BNT162. Doses of the vaccine were given to healthy volunteers at the medical schools of New York University and the University of Maryland. 

The companies said that if the vaccine turns out to be effective in trials, it could possibly be made available for U.S. distribution by this fall. The vaccine began experimental trials in Germany last month. 

The vaccine uses the messenger RNA technology that attempts to help humans develop an immune response to the virus. 

“With our unique and robust clinical study program underway, starting in Europe and now the U.S., we look forward to advancing quickly and collaboratively with our partners at BioNTech and regulatory authorities to bring a safe and efficacious vaccine to the patients who need it most,” Pfizer CEO and Chairman Albert Bourla said in a statement. “The short, less than four-month time frame in which we’ve been able to move from preclinical studies to human testing, is extraordinary.” 

President Trump, in a Fox News town hall on Sunday, said he was confident that an effective vaccine for the virus would be developed by the end of this year.

Dale Fisher, chair of the World Health Organization Global Outbreak Alert and Response Network, has called Trump’s comments “a bit premature,” and suggested that a vaccine would not be ready until the end of next year. 

Biotech firm Moderna is developing a vaccine with the cooperation of the U.S. government, with trials already having begun in March. Moderna recently signed a deal with Swiss pharmaceutical company Lonzo AG to produce one billion doses a year of the vaccine. 

Companies around the world are racing to find a cure for the virus. As of Tuesday at 2:30 p.m. ET, there are over 3.6 million cases of the virus in the world, with the global death toll over 254,000.