Hi, and welcome to COVID quickly, a scientific American podcast series. This is your fast track update on the COVID pandemic. We bring you up to speed on the science behind the most urgent questions about the virus and the disease. We demystify the research and help you understand what it really means. I'm Tanya Lewis. I'm Josh fishman. And we're a scientific American senior health editor. Today we're going to discuss what we really know about BA 5 reinfection. And we'll talk about one factor worldwide that is kept infections low. Trust in people around you. I'm hearing more and more stories about people getting reinfected with COVID, just a month or two after recovering from an earlier bout. Are those just stories or is reinfection really more common now with the BA 5 variant running around? I've been hearing those stories too, and it's true that BA 5 is better at evading our immune responses from past infection or vaccination than any variant we've seen so far. But the truth is, a prior infection does still give you some immunity, especially a prior omicron infection, a preprint study done in Qatar that has not yet been peer reviewed, found that a prior infection with a non archon variant gave people about 15% protection from symptomatic BA 5 or BA four are related variant. And 28% protection against any infection with those variants. Okay, that's something. What help does a prior omicron infection give? Those people had significantly more protection against reinfection with BA four or 5. 76% against symptomatic infection, and nearly 80% against all infection. In other words, if you had omicron in the winter of the spring, you're fairly well protected against getting it again now. That's right. And while it's certainly possible you could have had an earlier version of omicron and still get unlucky enough to catch BA 5, you're unlikely to catch the exact same variant twice in a short span of time. Well, that's good news. What about vaccination? How well does that protect you? Well, we already know the vaccines do a great job of protecting against severe disease in all the variants we've seen so far. But the booster shots are also critically important. Antibodies from vaccination weighing over time, making us more susceptible to infection. Thankfully, boosters can top up that protection even against omicron. The CDC conducted a recent study when BA two and related variants were circulating. It found that people over 54 months after a first booster were just 55% protected against being hospitalized with COVID. But after a second booster, that protection jumped up to 80%. Sounds like you're telling us now is a good time to make sure you're up to date on your booster shots. Absolutely. The reason we're seeing more reinfections with BA 5 is partly due to its immune invasiveness, mutations in its spike protein that help its sidestep antibodies to prior variants. And it's partly due to the fact that more people have simply had COVID by now, and their immunity may have waned since they first got infected. So it's a bit hard to compare the risk of reinfection with different variants. But in general, if you've had COVID or gotten boosted recently, it is safe to say you probably have some protection against reinfection and especially against severe outcomes. Throughout the pandemic, we've all been wondering why some people get infected and others don't. Age, immune system reactions, mask wearing, they all make a difference. But you've been looking at another surprising factor. Trust. It's true, Tanya. All of the things you mentioned do affect risk on an individual level. But looking across countries, the ones that have done best during the pandemic, keeping infection rates and death rates down, are the ones in which people have the most trust in one another, and in their governments. Trust is more important than how rich a country is or how many hospital beds it has or whether it had a good pandemic preparedness plan. That's wild. Trust really makes that big a difference. It does. Trust me. You just had to go there, didn't you? Yep. But let me explain it. The info comes from a study published in February in the medical journal the lancet. The authors looked at a 177 different countries and made dozens of comparisons about populations, governments, and healthcare systems. They looked at the period from the very start of the pandemic in early 2020 to when the delta wave peaked in the fall of 2021. Most of the differences in COVID outcomes just couldn't be explained by typical factors. I mean, you know the U.S. had one of the highest infection and death rates in the world. But it also had high per person income, lots of hospitals, and healthcare workers, and a government that functions pretty well. Okay, some of the time, and at least when compared with a lot of other places. But that stuff didn't really matter. Not so much. Countries like the Philippines and the Dominican Republic and Vietnam, which don't have U.S. type resources, had much lower infection and death rates during the time of the study. What places like Vietnam did have the authors say, was a really high level of trust in their government and in the people down the street. When you say trust, what exactly do you mean? How did they measure it? Good question. It was through big surveys. Several years of them, all around the world, and in these surveys people were asked basically how much they trusted officials and everyone else to do the right thing. But couldn't those answers be skewed? I mean, people in countries with a third terran governments might be scared to give an honest answer, right? You are right. But there are places like Denmark without such fears where people said they had really high levels of trust. And then there are places like the U.S. where people aren't scared of surveys and still had much lower levels of trust. In fact, the researchers estimate that if every country on the planet had levels of interpersonal trust like Denmark, global infections would have been 40% lower. That's 440 million fewer infections. Wow. But trust is a social thing, part of a relationship. How does it fight a virus? In a few ways, trust makes it easier for officials to communicate with people about the best protective measures. Strategies that engage communities that involve them in solutions help build that trust. High levels are linked to high vaccination rates and also to people agreeing to restrictions on moving around. Low trust and you get the bad patchwork of behaviors and anger that we've seen here. Between people neighbor to neighbor, trust makes people confident everyone is trying to protect one another. Not to harp on Denmark, but Siam just reported on crowd behavior in that country during the pandemic. People said they were comfortable gathering because they believed their neighbors wouldn't go out if they felt ill. And were likely to be vaccinated, which, indeed, they were. That makes sense. But in several of those high trust countries, such as Denmark and Vietnam, infections have spiked recently. Well, new virus variants are highly transmissible wherever you go. Countries relax protective measures and infections have gone up. We're definitely going to need better coronavirus vaccines. But some injections of trust would help too. Now you're up to speed. Thanks for joining us. Our show is edited by Jeff del vicio and tulika Bose. Come back in two weeks for the next episode of COVID quickly. And check out Siam dot com for updated and in depth COVID news.