The United States on Wednesday promised to buy 500 million more COVID-19 vaccine doses to donate to other countries as it comes under increasing pressure to share its supply with the rest of the world. #UnitedStates #COVID #Vaccines #US #News #Reuters Subscribe: http://smarturl.it/reuterssubscribe Reuters brings you the latest business, finance and breaking news video from around the globe. Our reputation for accuracy and impartiality is unparalleled. Get the latest news on: http://reuters.com/ Follow Reuters on Facebook: https://www.facebook.com/Reuters Follow Reuters on Twitter: https://twitter.com/Reuters Follow Reuters on Instagram: https://www.instagram.com/reuters/?hl=en