Credible case reports of #SARSCoV2 reinfections have started to emerge, in contrast to earlier reports that were certainly just persistent PCR+s. It's important to document these and studying such cases in large numbers will inform our understanding of SARS2 immunity. However
it does not mean that recovering from #COVID19 confers no protection. With any infection or vaccine, some subset of individuals are not going to develop lasting immunity. For example, the best vaccine we have, the measles vaccine is ~95% effective. That's great! Yet, if we
vaccinate 30 million people (approx # of US SARS2 infections) against measles, we'd expect up to 1.5 million susceptible to a measles infection. I think everyone agrees recovery from #SARSCoV2 isn't as "good" as a measles vaccine, so it makes sense that some people
are getting re-infected. None of this changes my expectation that the large majority of people who recover will be protected from re-infection for a short time (maybe 6-12 months average) and have *some* protection for a long time thereafter. We are of course
detecting the reinfections associated with severe disease. That doesn't mean second infections are worse, broadly. If you recovered from #COVID19 and get a cold 6 months later, you probably aren't getting tested again. A final point. Some of these stories are accompanied by
comments like "say goodbye to herd immunity, we need a vaccine." Of course we need a vaccine! But a vaccine won't magically confer more durable immunity than infection. It's likely first generation vaccines will be an annual event, like the flu vaccine, but I think more effective
