When Sen. Kamala D. Harris and Vice President Pence debate on Wednesday night, they’ll be seated 12 feet apart and separated by plexiglass barriers, installed despite the Trump campaign’s initial objections. Those barriers are, from a practical standpoint, useless to the point of being absurd.

But because of the message they send, they might still be a good idea.

First, the practical question. As we’ve learned more about how coronavirus spreads, it has become clear that aerosols — tiny particles that swirl around like smoke — are a critical way the virus can pass from person to person. Droplets — the larger, heavier particles pulled down by gravity — can contain the virus, but are less of a problem if people are spaced farther apart, as Harris and Pence will be.

Which is why, as one epidemiologist told the New York Times, “Those plexiglass barriers are really only going to be effective if the vice president or Kamala Harris are spitting at each other.” So a much more important unknown is the ventilation system inside the debate hall.

Another risk comes from the other people who will be present. It would have been much better to have this debate remotely, which isn’t some kind of technical challenge. But barring that, there should be no audience of family and staff, whether their chairs are set far apart or not.

We saw how, at the first debate, President Trump’s entourage refused to wear masks in the hall, despite the fact that they had agreed to do so. The Commission on Presidential Debates says that anyone who refuses to wear a mask at this debate will be expelled from the hall, but we’ll see.

And it’s particularly risky given that the White House has become a vector of covid-19 transmission, with each day bringing news of another close adviser to the president testing positive for the virus. The latest is the villainous Stephen Miller, whose wife happens to be one of Pence’s top aides.

That all relates to the immediate question of whether the vice president risks infecting Sen. Harris. The opposite is always a possibility, but given how aggressively hostile this administration has been to safety measures and how many people with whom Pence has had contact have contracted the virus, the risk of Republican-to-Democrat transmission seems much higher.

But what about those plexiglass barriers?

One comparison that comes to mind is the safety measures instituted after the 9/11 attacks that some derisively called “security theater,” defined by one analyst as “measures that make people feel more secure without doing anything to actually improve their security.” Much of the energy around protecting us from terrorist attacks went toward highly visible measures that didn’t actually prevent attacks, or protected against threats that were nearly nonexistent.

So what’s the difference? Security theater took place in a context where most of us could not actually do anything to increase our security; you might have the opportunity to see something and say something, but the chances that you’d actually be there when a terrorist attack was about to go down were about the same as being struck by lightning.

In this pandemic, on the other hand, there are specific things all of us must do to limit the spread of the virus. It’s still important that we have faith in the authorities to handle the problem — which has become impossible given who the president is — but it’s also important to keep reminding ourselves that this is a collective challenge in which we all have to do our part.

And yes, there’s a risk that a useless measure like these barriers will undermine the broader effort by convincing people that everything we do to contain the virus is just for show and can therefore be discarded. But it is still important to send a message not only about the virus but also about the Trump administration.

Masks are about all of us: I wear one not only to protect myself from you, but to protect you from me. They’re a symbol of our common predicament and our commitment to get past it: We’ll do this as long as we have to, all of us together, even if it’s inconvenient.

Putting up the plexiglass sends a similar message — that we shouldn’t forget that these are extraordinary times. Even though Harris won’t say this out loud, it also sends a message that she doesn’t trust Pence not to be infectious. As well she shouldn’t.

This is happening at a time when the man Pence will be defending has actively discouraged just about every public health measure that could have allowed us to get a handle on this pandemic much sooner, the way many of our peer countries did. Even after contracting it himself, Trump continues to characterize the pandemic as some kind of test of manliness whose most serious threat is to his image.

As one White House source told Axios, “It’s insane that he would return to the White House and jeopardize his staff’s health when we are still learning of new cases among senior staff. This place is a cesspool.”

So you can call the plexiglass barriers a symbol of how the recklessness and incompetence of this administration have divided us from one another. They may not keep anyone safe, but they won’t let us forget what Trump has done to the country.

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