Evans said there was "pretty clear evidence" that you get at least 80% protection — and "probably" better than 90% — for Pfizer's vaccine against COVID-19 with symptoms after a single dose. He said you couldn't be absolutely sure what happens after 21 days because it hadn't been fully tested.
you get at least 80% protection — and probably better than 90% — for Moderna's vaccine against COVID-19 with symptoms after a single dose for 28 days. After 28 days it was unclear because it hadn't been tested．
https://www.businessinsider.com/covid-vaccine-one-shot-effectiveness-pfizer-moderna-astrazeneca-vaccines-dose-2021-3
Evans said there was "pretty clear evidence" that you get at least 80% protection — and "probably" better than 90% — for Pfizer's vaccine against COVID-19 with symptoms after a single dose. He said you couldn't be absolutely sure what happens after 21 days because it hadn't been fully tested.
you get at least 80% protection — and probably better than 90% — for Moderna's vaccine against COVID-19 with symptoms after a single dose for 28 days. After 28 days it was unclear because it hadn't been tested．
觉得一针的实际效果应该测一下，特别是超过21天（Pfizer), 或者28天(Moderna) 以后，因为一针的好处实在太多太多了……
过几个月以后再去强化一针，这样总体的有效时效也许比两针连着一起打更持久……加拿大缺少疫苗，现行的做法有可能到头来反而更好。说不定四个月后疫情彻底控制，跟大家说第二针不需打了，或者出了针对新变种的加强版，美国人要打第三针，他们只要两针。
这次却是好事，80岁的才开始打疫苗，我个人主张越晚越好，越晚，疫苗的可靠性和副作用的研究数据就越清楚啊！
加拿大天寒地冻，地广人稀，感染的人也少（大城市多）。
我们医院一直都不给新住院病人做咽拭子，新病人或探视的如果阳性都可能传染给医护或其它病人。
有护士跟我说，以前她们觉得新冠跟流感差不多（因为只有感染的病人嘛），所以打疫苗时蛮多人不愿打，只到这个同事上了呼吸机，她们才感到horified，都跑去打疫苗了。
从现在的研究看，应该按规定打完两针。这种规定，是有大量试验做支撑的。
公立学校小孩必须打，但她送娃去私校，所以optional
再说对一些因为自身疾病原因不能打的人很不公平。
我一直以为中国从50年代起就全民种卡介苗，可结核照样还存在。
但是在具体应用过程中，由于各种情况(包括非医学的原因)，注射方式可能随时予以调整和修改。
未来旅行，特别是国际旅行恐怕需要完成疫苗注射护照。
欧盟已经在行动了。
说到底，就是吃点儿苦呗。
打吧，听人劝吃饱饭，不就是难受两天么？两天后满血复活，撂爪儿就忘了，何必计较。