Highly Pathogenic Avian Influenza Has Made the Jump to Mammals and That is Very Scary

Had a very scary telephone call this morning with a number of my technical and business colleagues discussing various aspects of the news that highly pathogenic avian influenza (HPAI-H5N1) has apparently made the jump to mammals with confirmed or suspected cases in dairy cattle herds across the country and several people who had been in close contact with said cattle are said to have symptoms of the flu though there has been no official confirmation of either humans with symptoms or any confirmed human infections. Rumors are flying that beef cattle have also been infected though there has been no confirmation of that of which I, nor anyone on the call, was aware. The persons taking part in this particular call were some of the most well connected to all aspects of the dairy and beef industries as any in the world, so if it were known, they would have known it. I don't take much comfort from that fact however, and was very disturbed to learn this morning in the very first email I opened in my overflowing inbox that cases, or at least symptoms, in humans working with the infected dairy cattle had also been reported. If this is in fact accurate then we have the possibility that highly pathogenic avian influenza has not only made the jump to mammals in the form of dairy cattle, but that this particular variant of the H5N1 strain also has the ability to be transmitted from cows to humans. This is scary stuff and I will admit I am much more nervous about this then I ever was about Covid19. Highly pathogenic avian influenza is not called that for nothing. It is in fact highly pathogenic. Fatality rates in susceptible bird populations regularly reach 99%. The jump to mammals is a thing that has always been highly feared but felt unlikely to occur due to the ridiculously high virulence of HPAI. In addition to limiting the spread of the virus the high lethality rate means that it has historically been under very little evolutionary pressure to mutate and thus potentially gain the ability to more readily infect a non- avian species. This is very unlike seasonal flu in humans which is under a ton of selective pressure and mutates left and right. Thus the reason we need a new flu vaccine every year. The fatality rate in infected humans is closer to 50% which might sound like a good thing, but is actually probably a net negative as it gives the virus more time to spread. That said for a human to become infected takes a ridiculously high exposure as the virus is not at all well adapted for survival and replication in humans and there has never been a confirmed case of human to human transmission. If that ever were to change, thankfully we always have optimal virulence to save us from a human species level extinction catastrophe even in the worst case scenario.

To be 100% clear there is no indication or even suspicion of human to human transmission at this time. I only mention it as an educational factoid and cheap plug for my very old article on the topic. Sorry I don't have references to cite for my numbers but I got them from a highly knowledgeable colleague with tons of real world experience in the area of highly dangerous pathogens research so I do believe they are accurate. If they are not expect a full retraction and apology in short order. I waited until the very end of the day today hoping I would get some good news suggesting that there had been some mistake and this was much ado about nothing. Unfortunately as of roughly 10:00PM PST that news has not been forthcoming and I need to call it a night. Here's hoping my inbox has better news awaiting me tomorrow morning.