Comment: There is no silver bullet that can defeat covid-19

As effective as vaccination is, it must be paired with masks, good ventilation and other steps.

By William Hanage / Special To The Washington Post

The arrival of the delta variant of the coronavirus in the United States upended premature declarations of victory over the pandemic. Hospitalizations have surged again, driven by infections in communities with low rates of vaccination. As the delta variant causes spikes, the likelihood of breakthrough infections even among vaccinated people grows because there is just more virus around.

Most cases like that are mild, but some can be severe. Last year, the summer surge in the Sun Belt was followed by the worst period of the pandemic in the United States. As autumn beckons, we’d do well to learn from previous missteps. And one of those has been the ongoing obsession with the search for a “silver bullet” capable of ending the pandemic with a single preferably easy (and cheap) intervention.

It is easy to understand and empathize with the wish for silver bullets, because people want to be able to declare the pandemic over; the quicker the better. But being understandable doesn’t always mean being right. Remember, the virus doesn’t do empathy. The virus only makes more virus.

Since the pandemic reached U.S. shores, policymakers, media outlets and regular citizens muddling through it all have seemed to reach for one simple solution after another. First it was more testing. Testing is essential but, without adding in the ability to isolate cases and interrupt transmission, it’s really only keeping score for the virus. Sensitive and specific rapid tests are great, but they need to be readily available and used by people including those who don’t know they are infected yet. Then we moved to masks, which can help significantly, but all masks are not alike. And they don’t remove the need for ventilation. Now people are looking to vaccine boosters to do the trick, even though a damagingly large share of the U.S. population has yet to receive even a first dose. Each intervention on its own is helpful, but they really come into their own when used together.

The closest thing we have to an actual fix is the vaccines. They are extraordinarily good at protecting you from serious disease, even with the delta variant. But they are not 100 percent effective, especially where mild disease is concerned. So while vaccines are the single key thing that matters to long-term control of the virus and the end of the pandemic, they still won’t bring that about overnight. That means the Centers for Disease Control and Prevention’s revised advice that even vaccinated people should wear masks in some contexts appears pragmatic.

Experts have known for some time that hoping to use a single intervention to control an infectious diseases is unwise, if only due to the fact that public health involves so many moving parts and priorities. Instead of silver bullets, experts prefer the “Swiss cheese model,” which represents different interventions as overlaid slices of caricatured holey cheese through which the virus tries to pass. If the virus makes it through the holes in one layer, it still has to make it through the rest. It all adds up to more protection.

To take a concrete example, I’d have been happy to go to a movie theater for most of 2020 if all the patrons were wearing masks and also had a negative rapid test result in the last 48 hours, even before the vaccines were available. The masks would help stop any infections that slipped through the testing net. It wouldn’t reduce risk to zero, but it would have been enough. Even now in my fully vaccinated state, if I go to a movie theater, I’ll wear a mask. Not because I am especially scared of the delta variant, but because I don’t want to contribute to a wave of uncontrolled transmission.

You will have noticed that this is not complicated: It’s basically the old saying about wearing a belt and suspenders. But the public at large moved on from the Swiss cheese model almost immediately in favor of waiting for the next silver bullet. That’s damaging because a fixation on one intervention as if it were overwhelmingly effective on its own leads to unreasonable expectations on the part of the public. The opponents of masks or vaccines — or indeed interventions in general — can then exploit this to suggest that, because these approaches are not universally effective under all circumstances, they have no point.

In reality, though, any means of reducing the risk of transmission can help. People are not great at thinking about risk, as we’ve demonstrated over and over through the pandemic. We cannot reduce risk of transmission to zero, and it is unreasonable to think that we need to do so if we want to make any difference.

Worse than obsessing about interventions that can’t end the pandemic on their own, though, is fixating on those that don’t work at all. Into this category we can bin hydroxycholoroquine and ivermectin as effective, safe therapies for covid-19. It was reasonable to investigate such drugs to see if they would work. But once the data were in, it became clear they were not going to transform the pandemic, let alone end it. However, this message has yet to filter through to many.

The notion of a silver bullet implies something new and shiny but, over the course of the pandemic, it has been painfully clear how many places have found it so hard to do the simple things well in the first place. Things like contact tracing really matter, especially when cases are rare. Ideas like improved ventilation, or support to enable exposed workers to isolate, might not be sexy and get headlines, but they’re essential nonetheless.

Along similar lines, I remain astonished that so far into this, there’s not been a national conversation about mandatory sick pay. Viruses don’t infect people by magic. They require contact with an infectious person, and enabling sick people to stay home without losing pay would reduce those contacts. Unfortunately, a national tussle with the delta variant is inevitable, and handling it won’t be helped by wishful thinking for an easy way out. Instead, we should prepare multiple interventions. These may not need to be incredibly onerous in well-vaccinated places.

The recent large outbreak in Provincetown, Mass., has not been followed by a large surge in the state, partially because of a high vaccination rate but also because of a rapid response by the local public health authorities and the reintroduction of mask mandates. Contrast this with the situation in Texas or Florida, where hospitalizations and deaths are setting records while political leaders show little evidence of any will to prevent them.

The coming months will be challenging. Many parts of the United States have vaccination rates similar to those in Texas and Florida, and so we can expect that as the nights draw in and the kids go back to school, the delta variant will gather force. Improved vaccine coverage would help greatly, by reducing the risk of severe disease and the resulting impacts on hospitals. But vaccines alone will not prevent spikes.

Because ultimately, the problem with silver bullets that slay the monster with one shot is that they only exist in stories. And the delta surge is all too real.

William Hanage is an associate professor of epidemiology at the Center for Communicable Disease Dynamics at the Harvard T.H. Chan School of Public Health.

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