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. More COVID-19 Vaccines in Pipeline as US Effort Ramps Up Associated Press A huge U.S. study of another COVID-19 vaccine candidate got underway Monday as states continue to roll out supplies of the first shots to a nation eagerly awaiting relief from the catastrophic outbreak. Public health experts say more options, in addition to the two vaccines now being dispensed -- one made by Pfizer and its German partner BioNTech, the other by Moderna -- are critical to amassing enough shots for the country and the world. The candidate made by Novavax Inc. is the fifth to reach final-stage testing in the United States. Some 30,000 volunteers are needed to prove if the shot -- a different kind than its Pfizer and Moderna competitors -- really works and is safe.