Gates Package — page 915

4. Variants and breakthrough cases weren't a surprise, but some subsequent waves were. Unless you work on infectious diseases, you had probably never heard of variants until COVID. The idea may have seemed new and scary, but there's nothing particularly unusual about variants. Influenza can quickly mutate into new variants, which is why we get a new flu shot every year--the vaccine needs to be updated annually to keep up with constantly shifting flu virus strains. Early in the pandemic, there was a broad assumption in the scientific community that mutations of COVID wouldn't cause a big problem. By early 2021, scientists knew that variants were emerging, but they appeared to be evolving in similar ways, leading some scientists to wonder whether the world had already seen the worst mutations that the virus was capable of. But the Delta variant proved otherwise--its genome had evolved to make it far more transmissible. The arrival of Delta was a negative surprise, but it finally convinced everyone that even more variants could show up. In future outbreaks, variants will always be a possibility. Scientists will monitor them closely to make sure that whatever new vaccines come out will still protect people from the variants. But, because every time a virus moves from one person to another is an opportunity for it to mutate, the most important thing will be to keep doing the things that we know reduce transmission: Follow the experts' recommendations on masks, social distancing, and vaccines,