As Covid-19 vaccines go into broad use, some rare side effects of vaccination will almost certainly emerge, like the reports of small numbers of people developing anaphylaxis. But so will medical events whose timing just comes down to random chance — and the potential ripple effects of those reports already have experts concerned.
Every single day, people die unexpectedly. They have strokes and heart attacks and seizures. On an average day, 110 people in this country may develop Bell’s palsy, a temporary facial paralysis, and another 274 will develop Guillain-Barré syndrome, a form of paralysis that usually resolves over time. The trigger for these medical events often isn’t known. But when they happen shortly after someone gets a vaccine — especially a new one — well,