Some things worth noting about this. 1) it really does look like a reinfection if the sequence is that different and typical of what is circulating in Spain 1/n https://www.nytimes.com/2020/08/24/health/coronavirus-reinfection.html

2) so this shows that reinfection is possible, it doesn't tell us how common it is. That will be a function of how much immune protection exists, and exposure to the virus (depends on current prevalence) 2/n

3) Hong Kong keeps a close eye out for things like this, so it's maybe not surprising it was reported from there. Should remember that when thinking about how common reinfection is 3/n

4) Notably the second bout of infection was reported as being milder than the first. That's somewhat encouraging, as this points to some protection from the first round when it comes to symptoms and no evidence of antibody dependent enhancement (although N=1) 4/n

5) a crucial question will be whether the 2nd infection was less transmissible than the first? If not, then reinfected people might be a further source of minimally symptomatic transmission. Measures of viral load would help clarify here 5/n

So far none of this is terribly surprising. But it does point to the way we are continuing to learn more about this virus. We will need to observe more cases of reinfection to fully understand their frequency and significance. We will likely get the opportunity 6/end