 Good morning, John. So you know how COVID-19 is a disease that is caused by SARS-CoV-2, which is a virus? It feels like it would be better and simpler if we just called that the COVID-19 virus, right? So why don't we just do that? Well, in the early 1900s, doctors started noticing something weird about some different diseases. They would sometimes have patients with shingles, a really specific disease where you get a very painful rash on just one side of your body. But then later, those patients' children would often come down with a totally different disease, chickenpox, which is like lots of different itchy bumps all over the body. So they started to think that those two diseases might be caused by the same pathogen, and they started to look for evidence of that. After a lot of work in the 1950s, it was finally confirmed separately in two different ways by two different scientists, Thomas Huckleweller and Evelyn Nicole. So this is one reason why we don't name viruses after the disease they cause. Indeed, it looks like SARS-CoV-2 might kind of cause more than one disease. There's COVID-19, and then there's like a blurry line between that and long COVID. If you wanna know more about long COVID, we did an amazing SciShow video about it. I'll put a link in the doobly-doo. The varicella zoster virus, though, which causes both shingles and chickenpox is a very clear-cut case. Children get chickenpox when they are infected by the varicella zoster virus, and that happens either through droplets in the air or through exposure to the fluid from the rash or the bumps, or more rarely, they can get it from exposure to a person with the shingles rash, which also contains the virus. Then almost all the time, quite quickly, the child's immune system will fight off the disease, and that virus will take refuge in your body for the rest of your life. It finds a place to hide, and that place is at the base of nerves near your spine. And then, as you get older, your immune system might get weakened by stress or by medication or just by getting older, and it will kinda forget about the herpes zoster virus, and that will allow it to spring forth and infect the nerve. At first, that causes like tingling and then itching and then pain as the nerves get inflamed, and this is why shingles almost always happens just on one side of the body in a specific area, because it's the individual nerve that is having the infection. The severity of the pain and discomfort from shingles, which I can now personally attest to because I'm getting over a case right now, feeling much better, but it was very, very bad. It doesn't hurt anymore, it just itches. It's one of the reasons why we vaccinate almost all children against chickenpox in the US now. This means far fewer kids are getting chickenpox, and in the future, they will be much less likely to get shingles as adults. Because you don't catch shingles. Shingles is, in effect, people might be mad at me for saying this, like long chickenpox. But other places that aren't the US are not vaccinating kids against chickenpox, and the reason why is wild and may include my individual case of shingles. In the US, 95% of adults have had chickenpox, which means that they could get shingles, but only around one in three of them will. But in 1995, we started to vaccinate pretty much every kid against chickenpox. In cases of chickenpox, among kids, of course, plummeted. And that meant that younger people, like me, were less likely to be exposed to the virus from sick kids. That exposure would be like a kind of natural vaccine that would work best for people in their 30s and 40s. Those people have fairly good immune systems. They're also more likely to be around sick kids. That would normally remind our immune systems to keep up the fight. Without those reminders, the immune system is more likely to let the virus already in our body start to replicate. And shingles slips through those cracks. And that's especially the case when combined with immune suppressant medication and stress, of which I have both. So in effect, I may have gotten shingles so that my son doesn't have to. Shingles rates kind of have to go up before they can go down. Rates of shingles in young people like me have indeed been on the rise, although it doesn't seem to be affecting the rates of shingles in older people where it is more dangerous. And that's also helped along by the fact that we now have a very effective shingles vaccine in addition to the separate chickenpox vaccine. Right now you can only get it if you're over 50 because it's in short supply, but my guess is it will be available to younger people eventually. This is just another example of how complicated disease and epidemiology and public health are. It's just all complicated and hard to figure out. And so I'm very grateful to all the people who are working to figure it out right now. And to the people who have worked to figure it out in the past, including Evelyn Nicole, who was in her 20s when she first isolated the varicella zoster virus and who died of complications from COVID-19 in 2020. John, I'll see you on Tuesday.