内华达州的奶牛群感染了此前从未在牛身上出现的H5N1禽流感病毒，这一消息披露后引起病毒学家和研究人员高度警惕。而且内华达州农业部发布的消息显示，想把该病毒从美国牛群中彻底清除，并不像联邦官员之前宣称或希望的那般容易。
2月7日又一个打击接连而至，可能还更严重。美国农业部一份技术简报称，这种叫D1.1的基因型包含一种基因突变，或许会让该病毒在包括人类在内的哺乳动物体内更容易复制。
而D1.1版本病毒，正是导致路易斯安那州一名男子死亡，加拿大一名青少年住院且病情危重的病毒变种。该病毒并非去年年初以来在患病牛群中常见的B3.13基因型。
“如果该病毒继续在奶牛中传播并感染更多人，可能引发深切关注，”免疫学家、前联邦卫生官员里克・布莱特向《财富》杂志表示，“目前该突变尚未导致人际传播加强，所以迹象无法证明其传播性有所提升。不过比起在奶牛中传播的（B3.13）病毒，这种病毒一旦感染人类引发的疾病很可能严重得多。”
“该病毒蔓延已迫在眉睫，”布莱特补充道，“为预防或降低病毒蔓延的冲击，相关准备仍然不充分。”
D1.1基因型已在北美迁徙路线的野生鸟类以及哺乳动物和家禽中检测到，因此传播到奶牛身上不足为奇。但很多病毒学家认为，内华达州奶牛群中发现标志着H5N1传播的拐点，意味着人类将面临更多麻烦。
“D1.1对人类的毒性似乎更大，可能表明在公共卫生风险级别上与早期B3.13毒株相比出现了重大变化，”美国国立卫生研究院（National Institutes of Health）新发及人畜共患传染病中心主任，也是兽医学领域领军人物于尔根・里希特向《财富》杂志表示。
针对一系列邮件提问，美国疾病控制和预防中心（CDC）发言人表示，该机构仍认为该病毒对普通公众的健康风险很低。“不过，与受感染鸟类或其他动物（包括家畜），或者与受感染鸟类或其他动物污染所处环境有密切、长时间，或无防护措施接触的人感染风险更高，”发言人表示。
2月7日美国农业部指出，在检测之前内华达州奶牛并无临床感染症状，但此后有报道称奶牛已明显发病，且奶牛场附近出现大批野生鸟类死亡。
人类是否应采取预防措施？风险程度如何？美国的农场和奶牛场是否已采取缓解措施？
种种问题的紧迫性表明，接下来几周内必须高度重视及时发布联邦机构的信息及检测的最新情况，因为研究人员和卫生官员往往依赖相关信息。可惜，当前不能太过指望信息顺畅流通。
1月21日，根据特朗普政府的命令，美国卫生与公众服务部（HHS）冻结了几乎所有的对外交流，包括文件和健康指导等，直到特朗普任命的官员到任并批准放行。此举并非没有先例，但信息冻结在2月1日的截止日期之后仍未完全解除，民主党领导人开始表示不满。
特朗普指令有个重大影响，即疾病控制与预防中心发布的《发病率与死亡率周报》（Morbidity and Mortality Weekly Report）受到冲击。这份报告向来是公共卫生问题的重要信息来源。1 月 23 日，《发病率与死亡率周报》60多年来首次未能按时出版，1月30日再次停刊。2月6日虽恢复发行，《华盛顿邮报》（Washington Post）报道称其中未提及禽流感，也没有原定于1月发布的三项 H5N1 研究的信息。
此外据《华尔街日报》（Wall Street Journal）报道，特朗普政府计划裁减美国卫生与公众服务部数千名员工。报道称，政府要求公共卫生高级官员根据员工的工作重要程度排名。
由于种种措施在卫生部门各机构的影响，禽流感追踪和新药批准等可能会受到影响。2023年，特朗普提名的卫生与公众服务部负责人小罗伯特·F·肯尼迪表示，他将对联邦卫生领域的科学家说，“感谢你们对公众的服务。接下来八年左右，传染病（研究）将暂停。”
事态发展导致追踪H5N1传播的科学家和研究人员越发担忧。美国疾病控制与预防中心称，H5N1现已感染美国959个奶牛群，导致1.56亿只家禽死亡，供应短缺推动鸡蛋价格创下历史新高。
研究人员还强烈呼吁，应考虑是否使用联邦储备的禽流感疫苗为奶业工人接种，以及在奶牛场和蛋禽养殖场为一线工作人员强制配备个人防护装备。
各种决策都有赖于信息及时流通和传播，然而专家表示在这关键时刻信息沟通受限。
“想想2020年新冠疫情开始时科学家遭封口，科学传播受到操纵，现在的情况令人寒心却毫不奇怪，”疫苗研究员布莱特说，2020年他曾举报投诉特朗普政府，几个月来一直敦促卫生官员加强禽流感检测和预防措施。
布莱特说，“2020年时，疫情应对速度放缓，公众对科学和公共卫生产生不信任，结果是更多人丧生。令人痛心的是，人们并没有吸取教训，当前情况跟当时同样糟糕乃至更差，不仅是在禽流感方面，美国对众多其他事件的应对同样有问题。”
内华达州一名官员向《财富》杂志透露，奶牛感染 D1.1 病毒的新病例追溯至丘吉尔县的奶牛场，目前已有六个牛群被隔离。此前，内华达州农业局长 J・J・戈伊科切亚曾对路透社表示：“显然，我们没能做好充分准备，否则病毒也不会侵入。” 戈伊科切亚称，内华达州的养殖户应遵循 “良好的动物健康安全实践，并加强生物安全措施”。
这一切对人类意味着什么？按照萨斯喀彻温大学（University of Saskatchewan）病毒学家安吉拉·拉斯穆森的说法，内华达州的疫情并不会直接增加人传人的可能性，只是“增加了动物传人的风险，也就是从奶牛传给农场工人”。除此之外，真正让研究人员感到担忧的是D1.1的突变能力（或许B3.13尚未出现类似突变）。其适应能力可能导致病毒更容易在人际传播。
“在已知的少数人类感染病例中，H5N1病毒的新基因型D1.1会导致严重疾病甚至死亡，”布莱特说，“内华达州的病例意义重大，因为现在我们清楚地知道H5N1病毒在奶牛之间，以及从一个农场到另一个农场传播多么容易。病毒不仅能从牛奶传播到其他哺乳动物，比如老鼠和猫，还能感染人类。”
内布拉斯加大学（University of Nebraska）全球卫生安全中心主任詹姆斯·劳勒表示，近几个月来，联邦卫生机构采取了“一些积极措施”，通过全美牛奶检测战略增加检测，还对人类进行流感检测和亚型分析。
“为了更好地控制风险，我们应该加强受感染奶牛群和动物的检测与隔离，推动更广泛的人类监测和检测，加快疫苗研发与生产。”劳勒说。布莱特还表示，临床医生需要知道病毒正在传播，而且要“检测流感，而不是靠猜。”
宾夕法尼亚大学（University of Pennsylvania）病毒免疫学家斯科特·亨斯利表示赞同，“我们要密切监测D1.1病毒，因为病毒已表现出适应能力，而且能引发人类罹患严重疾病。”亨斯利还提到，“现有的H5N1疫苗储备与D1.1病毒匹配良好，有望提供高度防护。仍需加快H5N1疫苗生产，以防病毒演化到人传人。”
与此同时，里希特表示应避免喝生牛奶，因为其中可能含有受感染奶牛的活病毒，应该勤洗手，遇到类似流感的病症要报告，才可能及时检测。目前加州州长已宣布进入禽流感紧急状态，卫生官员向农场工人发放了数百万件个人防护装备，各州或许可以仿效。
不过，遏制病毒的各项努力最终很大程度上取决于准确及时的信息传播，还有政府和卫生界携手努力抗击禽流感及相关毒株。
“关于D1.1，还有很多未知之处。未来几天和几周内，我们会加班加点地研究，”亨斯利说。在抗击病毒行动中，专家们将所获知识广泛共享将是关键。（财富中文网）
译者：梁宇
审校：夏林
The disclosure that dairy herds in Nevada have been infected by a version of the H5N1 bird flu not previously seen in cows, has put virologists and researchers on high alert. Among other things, the news from the Nevada Department of Agriculture, suggests that driving the virus out of the U.S. cattle population won’t be nearly as simple as federal officials once suggested—or perhaps hoped.
On Friday came a second and potentially more serious blow: A technical brief by the U.S. Department of Agriculture reported that the genotype, known as D1.1, contains a genetic mutation that may help the virus more easily copy itself in mammals—including humans.
This D1.1 version of the virus is the same variant that killed a man in Louisiana and left a Canadian teen hospitalized in critical condition. It is not the B3.13 genotype widely found in sick cattle dating to early last year.
“This can be of significant concern if this virus continues to spread among cows and infects more people,” immunologist and former federal health official Rick Bright tells Fortune. “This mutation has not been associated with improved human transmission, so there are no telling signs of enhanced spread yet. But when this virus gets into people, it is ready to cause a much more serious disease than the (B3.13) virus that has been circulating in cows before now.
“We have never been closer to a pandemic from this virus,” Bright adds. “And we still are not doing everything possible to prevent it or reduce the impact if it hits.”
The D1.1 genotype has been detected in wild birds in all North American flyways, as well as mammals and poultry, so it isn’t surprising that it’s made the leap to cows. But its newfound presence in the Nevada dairy herds is considered by many virologists to mark a sort of inflection point in the spread of H5N1, and it could spell more trouble for humans going forward.
“Given the fact that D1.1 seems to be more virulent in humans, this could indicate a major change in terms of public health risks from the earlier scenario with the B3.13 strain,” veterinary science pioneer Juergen Richt, Director of the National Institutes of Health Center on Emerging and Zoonotic Infectious Diseases, tells Fortune.
In response to an emailed series of questions, a spokesperson for the federal Centers for Disease Control and Prevention (CDC) said the agency still deems the risk to human health for the general public to be low. “However, people with close, prolonged, or unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection,” the spokesperson said.
The USDA on Friday noted that although the Nevada cattle did not display clinical signs of infection prior to its detection via testing, such signs have since been reported, along with die-offs of a large number of wild birds near the affected dairies.
Should humans be taking more precautions? What is the scope of the risk? And are there mitigating actions that should already be in place on America’s farms and dairies?
The urgency of those questions suggests that in the coming weeks, an absolute premium should be placed upon the timely dissemination of information and testing updates from the federal sources upon which researchers and health officials often rely. But that information flow is no longer to be taken for granted.
On Jan. 21, under orders from the Trump administration, the U.S. Department of Health and Human Services (HHS) placed a freeze on almost all external communications, including documents and health guidance, until a Trump-appointed official could be installed and approve them. Such a move is not unprecedented, but when the information freeze blew past its Feb. 1 deadline without being fully lifted, Democratic leaders began crying foul.
One important casualty of that action was the CDC’s Morbidity and Mortality Weekly Report. The MMWR, as it’s known, is a critical source of information on public health issues. The MMWR failed to publish for the first time in more than sixty years on January 23rd and again on January 30th. Publication did resume on February 6th, but there was no mention of bird flu nor any information about the three H5N1 studies which were scheduled to be published in January according to the Washington Post.
Further, per the Wall Street Journal, the Trump administration is reportedly planning to eliminate the jobs of thousands of U.S. Department of Health and Human Services (HHS) employees. Senior public-health officials are reportedly being told to rank employees based on how critical their roles are.
Depending upon where those cuts land across the various agencies of the department, practices like tracing bird-flu outbreaks and approving new drugs could be affected. And Trump’s nominee to run HHS, Robert F. Kennedy Jr., in 2023 said he’d tell federal health scientists, “Thank you for your public service. We’re going to give [studying] infectious diseases a break for about eight years.”
These developments have ramped up the concern of scientists and researchers tracking the spread of H5N1, which, according to the CDC, has now infected 959 dairy herds in the U.S. and been responsible for the death of 156 million poultry, sending the price of eggs to record highs because of scarce supply.
Researchers are also loudly asking whether dairy workers should be vaccinated using existing supplies from the federal stock of bird flu vaccine, and whether personal protective equipment should become mandatory on dairy farms and egg-laying facilities for frontline workers.
This all comes back to the timely flow of information and communication—and, experts say, it is being throttled at a critical moment.
“This is chilling but not at all surprising, given the gag put on scientists and the manipulation of scientific communication in 2020 at the start of the COVID pandemic,” says Bright, a vaccine researcher who filed a whistleblower complaint against the Trump administration in 2020 and has been urging health officials for months to ramp up testing and precautions around bird flu.
“When it happened in 2020,” Bright says, “it slowed the response, sowed distrust in science and public health, and as a consequence many more people died during that time. It is horrifying that lessons were not learned, and we find ourselves in the same or worse situation–not only on H5N1, but on numerous ongoing outbreaks in the U.S.”
A Nevada official tells Fortune that the new cases of D1.1 in cows were traced to dairy farms in Churchill County, with six herds placed under quarantine. Previously, the state’s agriculture director, J.J. Goicoechea, told Reuters, “We obviously aren’t doing everything we can and everything we should, or the virus wouldn’t be getting in.” Goicoechea said Nevada farmers needed to follow “good animal health safety practices and bolster biosecurity measures” for their animals.
Where does this all leave humans? According to University of Saskatchewan virologist Angela Rasmussen, the development in Nevada doesn’t directly increase the likelihood of human-to-human transmission, but rather “increases risk of zoonotic human cases—that is, from cows to farmworkers. Beyond that, it is D1.1’s ability to mutate (perhaps in ways B3.13 has not mutated) that concerns researchers. That adaptability may allow the virus to more easily spread from person to person.
“This new genotype of H5N1 virus, D1.1 was associated with more severe illness and death in the few known human infections,” Bright says. “It (the Nevada case) is a significant event, because we now know how easily H5N1 viruses can spread among dairy cows, from farm to farm, jump from milk to other mammals, including mice and cats, and even infect people.”
Federal health agencies have taken “some positive steps” in recent months to increase testing via a National Milk Testing Strategy, and of testing and subtyping influenza in people, says James Lawler, director of the University of Nebraska’s Global Center for Health Security.
“To better control risk, however, we should aggressively ramp up testing and isolation of affected dairy herds and animals, facilitate more widespread surveillance and testing in people, and accelerate vaccine development and production,” Lawler says. Clinicians also need to know that the virus is circulating, Bright says, and to “test for influenza, not guess.”
Scott Hensley, a viral immunologist at the University of Pennsylvania, agrees. “We need to closely monitor D1.1 viruses because they have already shown the ability to adapt and cause severe disease in humans,” Hensley says. “Our H5N1 vaccine stocks are well matched to the D1.1 viruses and would likely provide high levels of protection—we need to ramp up H5N1 vaccine production in case these viruses evolve to spread from human to human.”
In the meantime, Richt says, people need to avoid drinking raw milk, which might contain live virus from infected dairy cows, wash their hands often and report influenza-like illnesses, presumably so that tests can be run. States may follow the lead of California, where the governor declared a bird flu emergency and health officials have facilitated the distribution of millions of pieces of personal protective equipment to farmworkers.
Every effort to contain the virus, though, ultimately will depend to a tremendous extent on the distribution of accurate and timely information—and a government and health community that commits to fighting bird flu and its concerning strains.
“There is a lot that we do not know about D1.1. viruses, and we will all be working overtime to learn more in the coming days and weeks,” Hensley says. It is the mass sharing of what experts learn that will be most critical in the fight.