[ti:Fast-spreading Omicron Sub-variant Raises Concerns] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]An Omicron sub-variant of the COVID-19 virus [00:05.96]is spreading fast in many parts of the world [00:10.12]and raising concerns for experts. [00:14.16]This week, the Centers for Disease Control and Prevention [00:19.48]reported that BA.2, a sub-variant of Omicron, [00:25.60]has caused 35 percent of all new cases in the United States. [00:32.24]In the northeastern states, [00:35.24]including New York, New Jersey and Massachusetts, [00:40.64]BA.2 has made up more than half of the cases. [00:47.32]The total number of infections, however, has been decreasing [00:52.96]and officials around the country have lifted measures [00:57.64]such as required cloth face coverings and social distancing. [01:05.52]The Omicron variant of the virus was first reported [01:10.12]last November in South Africa. [01:13.96]It has three main sub-variants known as BA.1, BA.2 and BA.3. [01:23.92]Scientists believe they all appeared at the same time [01:29.32]but Omicron BA.1 was linked [01:33.04]to most of the cases reported over recent months. [01:38.48]Last month, the World Health Organization (WHO) said [01:46.08]reported cases of Omicron BA.2 [01:50.24]have been increasing in comparison to BA.1. [01:55.68]The health agency found that although BA.2 could spread faster, [02:02.24]it does not make people sicker than BA.1. [02:07.72]By Tuesday, the WHO wrote in its weekly report [02:13.20]that BA.2 had overtaken all other versions of the virus [02:19.56]in Southeast Asia, the Eastern Mediterranean, [02:24.08]Africa, the Western Pacific and Europe. [02:29.64]In Britain, the Office for National Statistics also reported [02:36.08]that cases of BA.2 infection [02:39.76]had outnumbered other versions by early March. [02:45.68]Dr. Anthony Fauci is the U.S. government's top infectious disease expert. [02:54.52]He told ABC's This Week program that the U.S. would likely [03:01.36]see an increase of infections like Britain. [03:07.00]Fauci said: "They have BA.2. [03:11.12]They have a relaxation of some restrictions such as indoor masking." [03:19.08]Additionally, immunity from vaccines [03:23.04]and past infections was also decreasing. [03:27.96]Dr. Eric Topol is head of Scripps Research Translational Institute. [03:36.52]He told the Associated Press, [03:39.24]"It's inevitable we will see a BA.2 wave here." [03:45.12]However, Ali Mokdad, a professor [03:49.52]at the Institute for Health Metrics and Evaluation (IHME) [03:56.04]at the University of Washington [03:59.20]does not expect a big increase in the U.S. in the coming weeks. [04:06.12]He wrote on Twitter: "Our models do not suggest [04:10.60]there will be much of an increase in the US in the next weeks, if at all. [04:18.16]However, it is possible that the rapid return [04:23.04]to pre #COVID19 behavior and the spread of BA.2 [04:29.92]could see a short period of increasing case numbers." [04:37.04]And an early study in Qatar also suggests [04:41.56]that vaccines from Pfizer-BioNTech and Moderna [04:46.96]will work against both Omicron sub-variants. [04:52.00]The results suggest that the level of protection against BA.2 [04:58.16]is about the same as for BA.1. [05:03.12]I'm Mario Ritter, Jr. 更多听力请访问51VOA.COM