On April 23, 2020, Donald Trump stood in the White House press briefing room and raised the prospect of an entirely new kind of Covid treatment. As the then-president saw it, patients might benefit if they received, among other things, injections of disinfectant into their bodies.

The brief, impromptu comments, quickly became the quintessential moment of Team Trump’s pandemic response, capturing the Republican’s ineptitude and the eagerness with which he embraced nonsense. Exactly one year later, Politico reported, “It was a watershed moment, soon to become iconic in the annals of presidential briefings. It arguably changed the course of political history.”

On the four-year anniversary of Trump’s bizarre rhetoric, President Joe Biden was only too pleased to draw attention to the incident, and a day later, the incumbent Democrat reemphasized the story anew. The New York Times reported:

On Air Force One, on social media and from the presidential lectern, President Biden has homed in on the infamous moment — one that crystallized the chaos of the Trump presidency — as he trolls his political opponent. “Remember when he was trying to deal with Covid, he said just inject a little bleach in your veins?” Mr. Biden said on Wednesday after picking up the endorsement of North America’s Building Trades Unions. “He missed it. It all went to his hair.”

A video of the comments suggested that Biden enjoyed both making the joke and the enthusiastic response from his audience.

There’s no great mystery here: Biden wanted to draw attention to one of Trump’s most humiliating moments, while simultaneously having a little fun with his rival’s appearance.

But just below the surface, there’s probably a larger strategy unfolding.

For his part, the presumptive GOP nominee has largely avoided talking about Covid lately, especially as Biden has started talking about it more. Consider the president’s rhetoric during an event in Scranton, Pennsylvania, last week:

“[W]hen the pandemic hit, Trump failed the most basic duty any president owes the American people: a duty to care and a duty to respond. Remember when he told us, ‘Don’t worry; this will all be over by Easter’? Remember when he told us, literally, inject bleach? … Think about it. Because he failed to care, not only did people die, but millions of Americans lost their jobs, their homes, their livelihoods.”

By some measures, at the heart of the 2024 presidential race is a memory test for the American electorate: Will voters remember Trump’s many failures? Will they recall the many reasons they voted him out of office in the first place?

Biden’s job isn’t just to celebrate his accomplishments and denounce Trump’s regressive and radical plans. It’s also to combat amnesia and refresh memories.

The disinfectant joke, in other words, checks more than one box.