I've seen a lot of online hate for AstraZeneca's "only" 70%-effective vaccine. TL;DR: this 70%-effective vaccine will work IF (big IF) enough people vaccinate. I'll explain in this thread. Please relay this to anyone who might not have the scientific background to understand.

The graph explains the "critical vaccine coverage" (percent vaccinated) to achieve herd immunity. Note that COVID-19 has an R0 of ~1.0-1.2, so pay attention in the regions around the bottom-two lines.

What this means is that, with a 70%-effective vaccine, we will need to have at least about 1/4-1/3 of people in our population vaccinated to achieve herd immunity. So YES, vaccines work, even if they're not "99% effective." You have to think big picture here.

Many people are decrying this "only 70%-effective vaccine" because it doesn't compare to Pfizer/Moderna's ~95%-effective counterpart. But those come with notable disadvantages, including difficulty of storage. AstraZeneca's can be stored in a regular refrigerator.

SO PLEASE, take that 70%-effective vaccine. If enough people take it, it will be effective for everyone. This is a bad analogy, but vaccines are like insurance. Enough people need to chip in for "critical coverage." But insurance isn't 100% effective for you, day to day, right?

Did you know that the typical flu vaccine is only around 40%-60% effective on a given year? But it works! So vaccinate, and make sure your loved ones do too!