American drug maker Johnson & Johnson said Friday that it's one shot vaccine prevented covid-19 in a large trial around the world. The vaccine, however, was less effective in South Africa where a worrysome variant is causing new infections. The Johnson &Johnson (J & J) trialed involved almost 44,000 volunteers. The company said vaccine work fast in the United States, with an afficacy rate of 72%. In latten American, afficacy was 66%. J & Jreported that South Africa saw the lowest afficacy rate of the vaccine at 57%. On Thursday, another American company * * reported its own covid-19 vaccine candidate was 89% effective among volunteers in Britain. But the results dropped to 49% with a small group of volunteers in South Africa. Two shot vaccines from ** and * were found to be nearly 95% effective against covid-19 in large trials. Those trials, however, were held mainly in the US and they took place before the spread of the new coronavirus variants from Britain, Brazil and South Africa. Dr. * is J & J's chief scientific officer. He noted that the World Health Organization considers a one-shot treatment to be the best choice to vacinate people during a pandemic. * also pointed to the trial's finding that the vaccine is 85% effective in preventing severe covid-19. This offers hope of helping ease the huge burden placed on healthcare system and communities. He said. Dr. * is the US government's top infectious disease expert. He said the Johnson & Johnson study was very encouraging. At a coronavirus brief thnk Friday, * called the emerging variants are wake up * for all of us. He added that the best way to prevent more coronavirus variants is by vacinating as many people as you possibly can. Johnson & Johnson say it will see US food and drug administration permission in early Feburary for emergency use of the vaccine requires a 50% or better afficacy rate for emergency use. Like other virus, SARS, COVID-2， the coronavirus that calls it caovid-19 is continuously changing. Sometimes, new varriants appera and disappear. Other times, new variants appear and spread across many countries. Medical experts are especially concerned about the 3 SARS-COVID-2 variants that came from Britain, Brizil and South Africa. The US government's Center for Disease Control and Pprevention says thety appear to spread more easily and quickly than other variants. In Britain, the coronavirus variant known B117 was first recognized in September 2020. It quickly spread throughout the country, and now it spreading throughout Europe, the United States and Canada. The voronavirus variant called P1 was first indentified in 4 travellers from Brazil who were tested at an airport near Tokyo, Japan in January. It has spread too many countries, including Germany, South Korea and the US. In South Africa, another variant called B1351 appeared in early October. It has sense spread to more than 30 countries, including Austrailia, South Korea and Ggermany. On Thursday, American Health offical reported the appearance of the South African variant in the US. They indentified 2 cases in the state of South *. The patients had no links to one another, and neither had travelled recently. The experts say this suggests community spread started with a yet an identified carrier. At this time, US Health Agency experts say there is no evidnece that new coronavirus variants cause more severe sickness or increase risk. However, sciencetists have reported that anti-bodies from a small number of people who had recovered from covid-19 were less effective against the variant from South Africa. Now, the results from J& J and ** trials confirmed that current vaccines might be less effective against the South African vaccines than others. Both * and * has since announced their testing or booster of the approved vaccines against the new variants.