正当新冠肺炎病例和住院情况在omicron亚变异体BA.5在美国持续下降的推动下，归因于其他omicron分支的感染比例正在上升。
根据数据根据疾病控制和预防中心的数据，截至上周五，BA.5目前占新病毒病例的67.9%。
剩下的病例由BA.4.6(已在美国传播数周)以及新发现的子变异体(如BQ.1、B.Q.1.1和BF.7)组成，这些变异体主要在欧洲传播。
这些变异被认为是欧洲感染增加的原因。根据最新周报根据世界卫生组织10月12日公布的数据，整个非洲大陆记录的新冠肺炎病例超过166万例，高于2004年记录的153万例前一份报告发表于10月5日
在整个疫情过程中，欧洲一直被认为是美国未来的风向标
我们应该关注新的子变异体吗?专家告诉ABC新闻，随着我们进入更冷的天气月份并进入室内，美国可能会看到新的一波浪潮，保持警惕很重要。
波士顿儿童医院(Boston Children's Hospital)的流行病学家兼首席创新官、美国广播公司新闻撰稿人约翰·布朗斯坦(John Brownstein)博士说，“在接下来的几个月里，我认为有理由期待我们可能会看到一波秋季浪潮。”“但我认为，这一波的强度仍是一个很大的问题。”
有哪些新的子变异体?
在BA.5之后构成最多病例的亚变异体是BA.4.6。根据CDC的数据，它是omicron亚变异体BA.4的一个分支，估计占新病例的12%。
然后是更新的亚变异体，它们最近开始在美国稳步传播:BQ.1和BQ.1.1，两者都是BA.5的分支，合计占新病例的12%。考虑到截至10月1日的一周，他们仅占新病例的3%，这是一个快速的增长速度。
旧金山加州大学的传染病专家Peter Chin-Hong博士告诉美国广播公司新闻说:“它似乎是凭空出现的。”“但它并不是突然冒出来的。它最早于夏季出现在尼日利亚，然后传播到欧洲和亚洲的其他国家，现在出现在美国。”
BA.5的另一个分支BF.7也在加速发展。它占美国新增病例的5.3%，高于两周前的3.2%。
与此同时，有报道称，另一个亚变异体称为XBB，它结合了omicron变异体和其他新冠肺炎变异体的多个菌株，主要在亚洲发现。到目前为止，美国还没有发现这种病毒。
对这些较新的子变异体知之甚少。初步数据表明他们有更好地逃避免疫的突变，无论是来自疫苗接种还是先前的感染，并且可能更具传播性。
这些分支可能传播得更快的另一个原因是，人类行为已经发生了变化。旅行正在达到疫情前的水平，孩子们回到了学校，大多数限制——包括蒙面，社交距离和接种疫苗的要求——已经结束。
有一些好消息。自9月份以来，针对BA.4和BA.5的二价强化剂已在美国获得批准，适用于12岁及以上人群和5岁及以上从上周开始。早期数据表明加强剂增加了抗体反应。
A worker in protective suit stands watch as masked residents wait in line to get their routine COVID-19 throat swabs tests at a coronavirus testing site in Beijing, Oct. 18, 2022.
安迪·王/美联社
因为这些子变异体与BA.4和BA.5有关，所以增强剂至少也能对它们提供一些保护。
“我认为有一个非常合理的预期，即疫苗，特别是新的加强剂，将提供良好的保护，”布朗斯坦说。“但我们仍然缺少许多真实世界的数据，特别是考虑到BA.5和BA.4的这些新型omicron变体开始在世界各地扎根。”
“我们希望从其他国家获得合理的见解，这将有助于为未来几个月的预测提供一些信息，但这些数据仍在汇编中，”他继续说道。
Chin-Hong说，和以前的变种一样，有理由认为最危险的是保护最少的美国人。
Chin-Hong说:“对于未接种疫苗的人，65岁以上从未接种过疫苗的人，或免疫功能低下的人，如果他们不保护自己，他们可能会变得更严重，甚至死亡。”
我们应该担心吗?
布朗斯坦说，他认为公共卫生官员应该保持警惕，继续跟踪这些亚变异体的传播，但公众还不应该担心。
布朗斯坦说:“我认为现在判断担忧的程度还为时过早。”。“当然，每个人都应该关注新的变种是如何出现的，尤其是当美国和全球的疫苗接种不均衡的时候。”
他补充说，“当我们试图弄清楚(发生了什么)时，公众健康和科学家现在应该是这种担忧的主要对象。”
布朗斯坦说，如果病例激增或出现新的变种，美国人应该愿意改变他们的行为，比如再次在室内戴口罩。
根据疾病控制中心的数据每日平均新冠肺炎病例截至10月16日止为35，000英镑，平均估价为新入院人数截至10月15日为2990人。
布朗斯坦说，如果卫生保健系统因激增而不堪重负，市或州一级的官员可能会考虑屏蔽，以减少进入医院的病人数量。
布朗斯坦说:“我认为，目标明确的掩蔽，特别是在医疗机构和长期护理机构等高风险场所，将是至关重要的，因为这些场所负责保护最脆弱的人群。”“除此之外，我认为这将真正受到地方案件的推动。”
COVID subvariants: What to know and should you be concerned?
Even asCOVID-19 cases and hospitalizationsdriven by the omicron subvariant BA.5 continue to fall in the United States, the proportion of infections attributed to other omicron offshoots is rising.
According todatafrom the Centers for Disease Control and Prevention, BA.5 currently makes up 67.9% of new virus cases as of last Friday.
The remaining cases are made up of BA.4.6 -- which has been circulating in the U.S. for weeks -- as well as newly identified subvariants like BQ.1, B.Q.1.1 and BF.7, which have been spreading mainly in Europe.
The subvariants have been attributed to an increase in infections in Europe. According to thelatest weekly reportfrom the World Health Organization, published Oct. 12, there were more than 1.66 million COVID-19 cases recorded across the continent, up from more than 1.53 million cases recorded in theprevious reportpublished on Oct. 5
Throughout the course of the pandemic, Europe has been considered a bellwether of what's come in the U.S.
Should we be concerned about the new subvariants? Experts told ABC News that the U.S. may see a new wave as we enter the colder weather months and move indoors and it's important to remain vigilant.
"In the next few months, I think there's reasonable expectation that we'll probably see a fall wave," said Dr. John Brownstein, an epidemiologist and chief innovation officer at Boston Children's Hospital and an ABC News contributor. "But the magnitude of that wave, I think, is still very much in question."
What are the new subvariants?
The subvariant that makes up the most cases after BA.5 is BA.4.6. An offshoot of the omicron subvariant BA.4, it's estimated to account for 12% of new cases, according to the CDC.
Then there are newer subvariants, which have recently begun steadily spreading in the U.S: BQ.1 and BQ.1.1, Both are offshoots of BA.5 and make up 12% of new cases together. This is a rapid rate of increase considering they made up just 3% of new cases for the week ending Oct. 1.
"It seems to have come out of nowhere," Dr. Peter Chin-Hong, an infectious diseases specialist at the University of California, San Francisco, told ABC News. "But it didn't really come of nowhere. It was first seen in Nigeria in summer and then spread to other countries in Europe and Asia, and now in the United States."
Another offshoot of BA.5 that is picking up speed is BF.7. It makes up 5.3% of new cases in the U.S., up from 3.2% just two weeks prior.
Meanwhile, there have been reports of another subvariant called XBB, which combines multiple strains of the omicron variant and other COVID-19 variants and has been detected mostly in Asia. So far, it has not been detected in the U.S.
Not much is known about any of these newer subvariants.Preliminary datasuggests they have mutations that are better at evading immunity, whether from vaccination or prior infection, and may be more transmissible.
Another reason these offshoots could be spreading more rapidly is because human behavior has changed. Travel is reaching pre-pandemic levels, children are back in school and most restrictions -- including masking, social distancing and vaccinations requirements -- have ended.
There is some good news. Since September, bivalent boosters that target BA.4 and BA.5 have been approved in the U.S. for those aged 12 and older and for thoseaged 5 and oldersince last week.Early datasuggests the booster increases antibody response.
Because these subvariants are related to BA.4 and BA.5, it's likely that the booster will provide at least some protection against them as well.
"I think there's a very reasonable expectation that the vaccines, especially with the new boosters, will provide good protection," said Brownstein. "But we're still missing a lot of real-world data, especially given that these new sort of omicron variants of BA.5 and BA.4 are starting to take hold in various parts of the world."
"We'll hopefully have reasonable insight from other countries that will help inform some of the forecast for the coming months, but that data is still being compiled," he continued.
Chin-Hong said it's also reasonable to expect, as with previous variants, that those most at risk are Americans with the least amount of protection.
"For people who are unvaccinated, those over age 65 who've never gotten a booster, or people who are immunocompromised, they may become more seriously ill and die if they don't protect themselves," Chin-Hong said.
Should we be concerned?
Brownstein said he thinks public health officials should remain vigilant and keep tracking the spread of these subvariants but the public should not yet worry.
"I think it's too early to tell the level of concern," Brownstein said. "Of course, everyone should be concerned about how new variants emerge, especially when there's uneven vaccination across the U.S and then across the globe."
He added, "The brunt of that concern should be on public health and scientists right now, as we try to work out [what's happening]."
Brownstein said Americans should be willing to modify their behavior -- like masking indoors again -- if cases spike or a new variant emerges.
According to CDC data, thedaily average of COVID-19 casessits at 35,000 as Oct.16 and the average estimate ofnew hospital admissionsis 2,990 as of Oct. 15.
Brownstein said if the health care system becomes overwhelmed by a surge, city- or state-level officials might consider masking to reduce the number of patients entering hospitals.
"I think that clearly targeted masking, especially in high-risk places like health care settings and long-term care facilities, will be critical, because those places are charged with protecting the most vulnerable," Brownstein said. "Beyond that, I think it's going to be really driven by local level cases."
