Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. US Drugmaker Begins Late-Stage Testing of Single-Dose COVID-19 Vaccine in US VOA News U.S. pharmaceutical giant Johnson & Johnson has begun late-stage human trials of a single-dose COVID-19 vaccine in the United States. Dr. Paul Stoffels, Johnson & Johnson's chief scientific officer, told reporters Wednesday that 60,000 participants have begun receiving the vaccine across 215 locations in the United States, as well as internationally in Argentina, Brazil, Chile, Colombia, Mexico, Peru and South Africa.Dr. Stoffels said Johnson & Johnson moved into the late-stage trial after seeing positive results from its combined Phase 1 and 2 trials in the U.S. and Belgium. The Johnson & Johnson vaccine is the fourth potential coronavirus vaccine undergoing large-scale Phase 3 testing in the United States, joining Moderna, AstraZeneca and a joint effort by Pfizer and German-basedBioNTech. All four efforts are being developed under the Trump administration's [1]Operation Warp Speed coronavirus vaccine initiative, which aimsto deliver 300 million doses of an approved vaccine by January 2021. Because it can be administered by a single dose, Johnson & Johnson's vaccine has significant advantages over the other three potential vaccines, which require two doses. The single-dose vaccine would not have to be kept frozen in ultracold temperatures, making it easier to utilize in a mass immunization campaign. U.S. President Donald Trump hailed the announcement from Johnson & Johnson on Twitter Wednesday. "Big news. Numerous great companies are seeing fantastic results. @FDA must move quickly!," he wrote, referring to the U.S. Food and Drug Administration, which would give final approval to any new vaccine. Big news. Numerous great companies are seeing fantastic results. [2]@FDA must move quickly! [3]https://t.co/2pDrmRPOxc -- Donald J. Trump (@realDonaldTrump) [4]September 23, 2020 President Trump told reporters at the White House Wednesday that he may reject a proposal by the FDA to implement a set of strict new guidelines for emergency authorization of a new COVID-19 vaccine, saying it sounded "like a political move." The new rules, first reported Tuesday byThe Washington Post,would require drug makers to observe participants in late-stage clinical trials for at least two months after they receive a second and final dose of an experimental vaccine. If the new rules are adopted, an emergency authorization would come well after the November 3 presidential election, the date the president has constantly predicted such a vaccine would become available. Trump's threat to reject the proposed new guidelines from the FDA came hours after the agency's head vowed that"science will guide our decisions" as the agency decides whether to give full or emergency authorization to a coronavirus vaccine. References 1. https://www.hhs.gov/about/news/2020/06/16/fact-sheet-explaining-operation-warp-speed.html 2. https://twitter.com/FDA?ref_src=twsrc%5Etfw 3. https://t.co/2pDrmRPOxc 4. https://twitter.com/realDonaldTrump/status/1308740116643491842?ref_src=twsrc%5Etfw .