https://blog.wongcw.com/2021/04/09/%e7%be%8ecdc%ef%bc%9a%e5%8d%b3%e4%bd%bf%e5%ae%8c%e5%85%a8%e6%8e%a5%e7%a8%ae%e4%ba%86covid-19%e7%96%ab%e8%8b%97%e6%b0%91%e7%9c%be%e4%b9%9f%e6%87%89%e9%81%bf%e5%85%8d%e5%8e%bb%e5%8a%a0%e6%8b%bf%e5%a4%a7/
美CDC:即使完全接種了COVID-19疫苗民眾也應避免去加拿大旅行