[ti:Pfizer Seeks Approval of Latest Vaccine to Fight COVID-19 Variants] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]Pfizer has sought government approval [00:03.56]for a new combination COVID-19 vaccine [00:07.96]that aims to protect against new virus versions. [00:12.96]The American drug maker [00:16.08]officially requested the approval on Monday. [00:20.40]The combination vaccine seeks to target [00:24.32]new mutations of the Omicron version, [00:28.24]or variant, of COVID-19. [00:31.68]The latest mutations, or "sub-variants," [00:36.56]have been identified as BA.4 and BA.5. Omicron [00:45.12]and another virus version, Delta, [00:48.48]spread especially widely across the world. [00:52.68]Research has shown that the two sub-variants [00:57.60]are better at avoiding the protection developed in people [01:02.52]who were vaccinated or infected before. [01:06.92]The U.S. Food and Drug Administration (FDA) [01:12.16]had ordered vaccine makers [01:14.72]to target the BA.4 and BA.5 sub-variants [01:20.80]to prepare for new booster campaigns in the autumn. [01:26.96]The two most widely used COVID-19 vaccines [01:31.56]– one made by Pfizer and its partner BioNTech [01:35.84]and the other by Moderna [01:38.24]– have saved millions of lives worldwide. [01:42.32]But medical researchers have urged drug companies [01:47.20]to update their vaccines as the virus continues to mutate [01:53.28]into new variants and sub-variants. [01:56.88]Pfizer-BioNTech aims to offer updated boosters [02:02.16]to individuals 12 and older. [02:05.44]The shots could begin within weeks if the FDA [02:10.32]quickly approves the vaccine, The Associated Press reports. [02:16.20]Moderna is expected to also seek government approval soon [02:22.24]for a new combination vaccine. [02:25.36]The United States has a contract to buy 105 million [02:31.64]of Pfizer's shots and 66 million Moderna ones. [02:37.68]"It's going to be really important that people this fall and winter [02:43.76]get the new shots," Dr. Ashish Jha told reporters last week. [02:50.24]He is chief of COVID-19 policy for U.S. President Joe Biden. [02:57.52]Jha added that the new combination vaccines [03:01.96]are "designed for the virus that's out there." [03:05.80]Health officials say the BA.5 sub-variant [03:11.24]is currently causing almost all COVID-19 infections [03:16.44]in the U.S. and much of the world. [03:20.32]But health experts say there is no way to know [03:25.16]whether it will still be a threat this winter [03:29.00]or if another mutation will replace it. [03:32.72]The vaccines currently used in the U.S. still [03:37.68]offer strong protection against severe disease and death, [03:43.36]especially if people have received booster shots. [03:48.04]But those vaccines target the COVID-19 version [03:53.28]that started widely spreading in early 2020. [03:57.84]The current COVID-19 vaccines work [04:02.44]by causing the production of antibodies [04:06.08]that recognize and attack the so-called [04:09.80]"spike protein" that surrounds the virus. [04:14.16]The new combination vaccines will contain instructions [04:19.40]for both the original spike target, [04:22.48]as well as spike mutations carried by BA.4 and BA.5. [04:30.24]The Pfizer-BioNTech request comes [04:34.32]after Britain recently became the first nation in the world [04:39.04]to approve a different update to Moderna's COVID-19 vaccine. [04:45.48]While considering the U.S. approval request, [04:49.68]the FDA is expected to depend heavily [04:53.76]on scientific testing of past changes to the vaccine formula. [05:00.88]This process is similar to how vaccines [05:04.60]for the influenza virus are updated yearly. [05:09.04]They do not require large research studies. [05:14.60]Pfizer and BioNTech have said they expect [05:18.60]to start new trials involving BA.4 and BA.5 booster shots [05:25.88]in the coming weeks. [05:27.88]Moderna has begun a similar study, [05:31.36]but those results are not expected to be available [05:35.68]before a fall booster campaign. [05:38.88]In another development, Pfizer announced [05:42.76]that trials of its COVID-19 vaccine [05:46.36]showed the shots were 73 percent effective [05:50.76]in protecting children younger than 5 [05:54.44]during testing in the spring. [05:57.44]I'm Bryan Lynn. 更多听力请访问51VOA.COM