Reassurance isn't what's called for. And it's not what people are searching for.
What's needed is honesty. Here's what I say: 1/ https://twitter.com/nytimes/status/1338629858210033669

1. mRNA vaccines (Pfizer, Moderna) appear to be incredibly effective at preventing symptomatic disease. Better than we'd ever dreamed.
2. The side effect profile after two months is similar to other vaccines that protect against viruses. 2/

3. These vaccines are not FDA approved; rather, companies have permission to vaccinate people under an emergency authorization. Approval won't happen until spring because we don't know the rare and/or long-term side effects. 3/

4. The most experienced vaccine researchers breathe a sigh of relief after 3 million doses have been given. At that point, we'll have a handle on rare events. Most people in the U.S. will not have access to a #COVID19 vaccine until far more than 3 million have been vaccinated. 4/

So if you're nervous today, that's okay. You're not alone. But when it's finally your time to get the vaccine, we'll have an even better sense of the true risks and benefits. What's happening now is just a huge experiment, one that I'm confident will succeed.