2. 关于疫苗，很好奇效果到底能有多大？大家都知道Influenza Viruses每年流行的Strains不同，生产疫苗一半要靠猜，所以打了疫苗也不一定完全保险，对吗？同理，虽然感染后自身有了抗体，但病毒传了几轮后变异了，会不会再次感染？
这个问题朋友刚回复了我，copy过来：These viruses "are still so genetically similar that these mutations shouldn't alter a new vaccine," Grubaugh said. It's "unlikely that the developers have to worry about this." Once the vaccine is out, however, the virus could adapt to it and develop resistance, he said, but considering that other RNA viruses — such as those that cause measles, mumps and yellow fever — didn't develop resistance to vaccines, that scenario is unlikely. https://www.google.ca/amp/s/www.livescience.com/amp/coronavirus-mutations.html
但是流感病毒也是RNA病毒，流感疫苗为啥不那么有效呢？
3. 这病毒是SARS2，会不会象SARS一样自己消失？
希望专家能帮助解惑。谢谢。
