Two scenarios could derail trust in the vaccines. Here’s how we must prepare for them.

Here’s one that will almost certainly occur: A large number of people will experience side effects. In Phase 3 trials of both vaccines, 10 to 15 percent of participants reported significant noticeable symptoms. Some were self-reported to be severe and included fatigue, pain and swelling at the injection site, headache and muscle aches.

Susan Froehlich, a trial participant, told CNN that “every part of my body was hurting for about four hours.” Another participant and a physician himself, David Yamane, said to me that he developed chills and a headache, and that he was so fatigued he fell asleep on the couch midafternoon and woke up the next morning drenched in sweat. “These symptoms are no joke,” he said.

Having side effects isn’t a bad thing; in fact, it signifies that the body is mounting an appropriate immune response. Though they could be uncomfortable for several hours to a few days, they are not comparable to having the coronavirus, which can cause weeks of illness or even long-lasting consequences and death.

It must be made clear from the outset that side effects are normal and expected. Downplaying them can only backfire. Both the Pfizer and Moderna vaccines require two doses — a primer and booster shot — and someone who experiences an unpleasant side effect after the first shot may not return for the second. It’s important to hear from people such as Froehlich and Yamane about what they went through and why they remain huge proponents of the vaccine. Those receiving vaccines also must be advised on home care (for example, take Tylenol or ibuprofen for fevers and aches); otherwise, many may go to the ER and further strain an overtaxed health-care system.

To be clear, my nightmare scenario isn’t the side effects themselves, but rather the misinformation about them that could dissuade people from getting vaccinated. Every year, I have patients who refuse the influenza vaccine because they swear that they “got the flu” from it previously. This isn’t possible, since the flu vaccine doesn’t contain live virus (and neither does the coronavirus vaccine). It’s hard but necessary work to explain that flu-like symptoms, a temporary side effect, are worth the trade-off for longer-term protection.

The same education must be done for the coronavirus vaccine, but on a much more compressed time frame. The front lines of fighting misinformation are doctors, nurses and pharmacists. Now is the time to train them on how to counsel patients about the new vaccines and counter anti-vaccine myths.

Then there’s my second nightmare situation: People will die of other causes, and the deaths will be wrongly attributed to the vaccine. Residents in long-term-care facilities are one of two priority groups that will access the vaccine first. Most people in nursing homes are elderly and have multiple underlying health conditions. When millions of medically frail individuals are being observed over months, some will become ill and die. These events will have nothing to do with the vaccine, but a few highly publicized incidents could fuel conspiracy theories.

Let’s say that someone receives a vaccine and then — unrelated to it — succumbs to a heart attack. Heart disease is the No. 1 cause of death in the United States, and the individual may have had long-standing conditions that led to the tragic outcome. Still, the time course could raise questions. What happens if several people have heart attacks in the days after they receive a vaccine — how does one prove that the vaccine was not the cause?

There are ways to anticipate and mitigate this concern. In advance of mass vaccinations, the Centers for Disease Control and Prevention can provide baseline numbers for expected illness and death among nursing home residents. If, say, 50 people in a given time period would be predicted to die of heart disease, that provides statistical context for interpreting individual tragedies. In addition, every possible adverse event must be investigated immediately, with full transparency and complete rationale provided to the public. Otherwise, disinformation will fill the void.

With at least two vaccines that appear to be safe and extremely effective, there is a real chance we could put an end to the coronavirus pandemic by late 2021. But for that to happen, vaccines must be trusted, and trust can be quickly eroded. The unprecedented speed of scientific development must be matched by a similar urgency in public education. The stakes could not be higher.

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