Biden and Harris are playing a Trumpian game on vaccine safety

Democrats have a good argument that they’re the only party in this election actually looking out for the good of the country, rather than narrow self- interest. One need only consider the way the two presidential candidates responded to a question during Tuesday’s debate about the likelihood that it could take some time to get a definitive vote count:

“Will you urge your supporters to stay calm during this extended period, not to engage in any civil unrest? And will you pledge tonight that you will not declare victory until the election has been independently certified?”

Joe Biden answered: “Once the winner is declared after all the ballots are counted, all the votes are counted, that’ll be the end of it. ... If it’s not me, I’ll support the outcome.” President Donald Trump steadfastly refused to make a similar declaration.

Sadly, that’s about what we expect from Mr. Trump and increasingly, the Republican Party, for whom no civic value merits as much protection as Mr. Trump’s ego.

So Democrats have a good claim that they are the real party of “America First.” Unfortunately, they undercut it every time they suggest there could be something wrong with any good vaccine news we hear before the election.

Mr. Biden slyly implied as much during Tuesday’s debate: “In terms of the whole notion of a vaccine,” he said, addressing viewers at home, “we’re for a vaccine, but I don’t trust [ Trump] at all. ... What we trust is a scientist.”

This was positively restrained compared with Democratic vicepresidential nominee Kamala Harris ( Calif.), who told CNN recently that she’d hesitate to take any vaccine approved before the election, after suggesting that government experts overseeing the approval process would be “muzzled ... suppressed . . . sidelined. Because he’s looking at an election coming up in less than 60 days, and he’s grasping for whatever he can.”

There’s a cold political logic to this. It is possible, although not necessarily likely, that one of the final trials in progress will deliver, by the end of October, the exciting news that their vaccine seems to be quite effective. That news would probably, all else equal, benefit Mr. Trump. If Democrats can nurture the idea that such a revelation is likely to be a political lie manufactured by the Trump administration, then maybe some voters who could have been nudged toward Mr. Trump will instead stick with Mr. Biden, or stay home.

But there are some things no decent person or party can do for political advantage. One of them is to gin up implausible claims of mass fraud to avoid ceding an election they lost. Another is to cast doubt on a potentially lifesaving vaccine during a pandemic.

The defenders of Mr. Biden and Ms. Harris would, of course, argue that they didn’t actually say you shouldn’t take any vaccine that was overseen by the Trump administration. But that defense is positively, well, Trumpian.

Clearly, the perception of political influence is a problem, especially with the Centers for Disease Control and Prevention guidance, but it has also been a problem for the Food and Drug Administration, where accusations swirled around its approvals of hydroxychloroquine and convalescent plasma. These were questionable, but defensible decisions — and it’s worth noting that the FDA withdrew the hydroxychloroquine authorization after better data indicated that the drug didn’t seem to help; convalescent plasma, meanwhile, is a relatively low- risk treatment that is likely to provide at least some benefit — that could have been influenced by politics.

But Mr. Trump did not get the CDC to claim that COVID- 19 is just a bad cold. And he won’t get the FDA to approve a useless or dangerous vaccine. For one thing, the standards for judging the efficacy and safety of vaccines have already been set. It’s virtually impossible to imagine the FDA abandoning them — especially without immediate mass resignations — or any pharmaceutical company wanting to go along, given the reputational, moral and legal price they’d soon pay.

Mr. Trump’s awful behavior certainly stokes such fears, and Mr.

Biden and Ms. Harris are only voicing worries the Democratic base already had — a declining fraction of Americans say they’ll take a vaccine immediately, thanks largely to concerns about the approval process.

But that’s precisely why politicians such as Mr. Biden and Ms. Harris must reassure them. If they don’t, the fear will linger long after the election — either because Mr. Trump wins, or because he loses, but people remember that his FDA oversaw the vaccine trials.

If Mr. Trump loses, Mr. Biden and Ms. Harris will, of course, be eager to assure people that any available vaccine is A- OK! Marvelously effective, and safe as a Sunday walk! But by then it will be too late: The seeds of doubt they planted will be in full flower. Such distrust could prove deadly, not just for individuals who will get sick as a result of it, but also for a new administration trying to guide the United States into a post- pandemic world.