I understand wary, although if I were on the front lines or behaving in a risky manner, I'd have zero issue getting either mRNA vaccine, as soon as the FDA approves the EUA and presumably shares more details from the ongoing clinical trials (they have to) and assuming those data don't raise any red flags. For me even a 1 in 20K chance of a serious adverse event (and it should be far less than that, with 1 in 20K being the absolute worst case, since there were no serious adverse events, due to the vaccine, so far) is not worth the 72 in 20K risk of dying for people aged 50-64 (43K deaths from COVID for ~12MM people, assuming ~20% infected so far; that's about 8X the death rate from flu for that age group) and about the 500-1000 per 20K chance of a serious illness.
Perhaps for young, healthy people, the comparison isn't as clear cut, although if the risk of death and serious adverse events are actually more like 1 in 500K or more, as one would expect given the data so far and comparison to past history of other vaccines (and we'll know this better in about a month after 10MM+ are vaccinated), then getting the vaccine still would make sense to me, as the chances of dying for 25-34 year olds are 0.022% or 4.4 in 20K or 110 in 500K (2037 COVID deaths over 20% of 46MM people). It would also be helpful to confirm if vaccinated people are less likely to transmit the virus (should be the case, but not proven yet), as that's another reason to get the vaccine.
Having said all that, I'm not a high priority, so I'll have to wait and I'm ok with waiting, as we're very conservative on contact with anyone and I'm ok with people at much greater risk of infection getting the vaccine before me. That will also give us the luxury of knowing a fair amount more about the vaccines and their efficacy/safety by the time we get vaccinated.
With regard to side effects, another angle we're going to need to consider is the media frenzy/scare angle, which we know is real. Derek Lowe has a nice blog article on this from Friday, where he talks about the fact that any sample of 10MM people, vaccinated or not, is going to have quite a few deaths (14K) and many other medical maladies and there will be reports about some of these being "due to" the vaccine and that will likely scare some people away from getting the vaccine, unfortunately. This is not the same as the flawed argument circulating that deaths from COVID aren't really due to COVID, as those deaths are signed off on by doctors and the 300K+ excess deaths so far this year is an independent check that the 275K deaths we've seen from COVID are truly due to COVID.
https://blogs.sciencemag.org/pipeline/archives/2020/12/04/get-ready-for-false-side-effects
Bob Wachter of UCSF had a very good thread on Twitter about vaccine rollouts the other day, and one of the good points he made was this one. We’re talking about treating very, very large populations, which means that you’re going to see the usual run of mortality and morbidity that you see across large samples. Specifically, if you take 10 million people and just wave your hand back and forth over their upper arms, in the next two months you would expect to see about 4,000 heart attacks. About 4,000 strokes. Over 9,000 new diagnoses of cancer. And about 14,000 of that ten million will die, out of usual all-causes mortality. No one would notice. That’s how many people die and get sick anyway.
But if you took those ten million people and gave them a new vaccine instead, there’s a real danger that those heart attacks, cancer diagnoses, and deaths will be attributed to the vaccine. I mean, if you reach a large enough population, you are literally going to have cases where someone gets the vaccine and drops dead the next day (just as they would have if they *didn’t* get the vaccine). It could prove difficult to convince that person’s friends and relatives of that lack of connection, though. Post hoc ergo propter hoc (after this, therefore because of this) is one of the most powerful fallacies of human logic, and we’re not going to get rid of it any time soon. Especially when it comes to vaccines. The best we can do, I think, is to try to get the word out in advance. Let people know that such things are going to happen, because people get sick and die constantly in this world. The key will be whether they are getting sick or dying at a noticeably higher rate once they have been vaccinated.
No such safety signals have appeared for the first vaccines to roll out (Moderna and Pfizer/BioNTech). In fact, we should be seeing the exact opposite effects on mortality and morbidity as more and more people get vaccinated. The excess-death figures so far in the coronavirus pandemic have been appalling (well over 300,000 in the US), and I certainly think mass vaccination is the most powerful method we have to knock that back down to normal.
That’s going to be harder to do, though, if we get screaming headlines about people falling over due to heart attacks after getting their vaccine shots. Be braced.