Global concern about novel coronavirus, or COVID-19, is at its highest level yet. The World Health Organization is warning that countries should “do everything you would do in preparing for a pandemic.” Many people are now considering the effect of the virus on them personally—and wondering how they can minimize their chances of being infected.

The good news is that there is a behavior that clearly helps: good hand hygiene, in particular washing your hands. For example, official guides for managing pandemic influenza emphasize hand hygiene as a way of decreasing transmission (Note: Influenza and the novel coronavirus are different, but we can learn from flu preparation and protocols). We know from controlled studies that handwashing is effective at removing viruses from the hands. Hand sanitizer (alcohol-based hand rubs) can also be effective for some types of influenza, but handwashing has broader benefits and therefore is the option that the U.S. Centers for Disease Control & Prevention (CDC) recommends.

The bad news is that people find it quite hard to wash their hands effectively and consistently.

In 2008, a study found that 28 percent of commuters in five different cities had fecal bacteria on their hands.

In 2008, a study found that 28 percent of commuters in five different cities had fecal bacteria on their hands. This is a universal problem: even healthcare professionals struggle, despite the immediate benefits to patients. People report that they wash their hands much more often than they actually do, and they wash less when they think they are not being observed. Most importantly, interventions to increase handwashing often show underwhelming results that may not be sustainable.

Why don’t we wash our hands as much as we should?

Behavioral science can help identify some of the key barriers. It may also suggest what might make a difference for COVID-19 in the absence of a vaccine, recognizing that there is much we still do not know about this virus.

The first barrier may be a lack of awareness about the effectiveness of soap, water, and scrubbing. People may simply not realize how well specific handwashing actions can prevent the spread of infectious disease. This is why many public health agencies run educational campaigns, which may have varying effects based on how far they take evidence about behavior into account.

For example, last weekend the Behavioural Insights Team (BIT), the organization for which I work, ran a set of online trials with 3,500 U.K. adults to test the impact of various posters on people’s intended handwashing behavior. We found that posters seemed to have stronger effects on people who were already washing their hands more frequently. In other words, the more compliant people got more compliant. Obviously, this is a real problem for infection control.

One specific issue with COVID-19 may be that people’s attention is being drawn to something else instead: face masks. In many countries, face masks in public are uncommon. Therefore, people in these places are more likely to notice when others are wearing masks, since doing so is visible and novel—unlike washing of hands! This may create the perception that wearing a face mask is the priority for preventing infection.

The evidence base on face masks is changing week-by-week. (Indeed, has developed a lot since I wrote this article in late February.) Given the increasing evidence around aerosol transmission of COVID-19, the benefits from face masks seem clearer. The CDC now recommends wearing a cloth face covering in public, especially “where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies).” However, it remains the case that if supplies are limited supply, medical face masks need to be reserved for the people and situations where they can do the most good. (This section was updated on April 15, 2020 to reflect the revised recommendations regarding face masks.)

And there is still legitimate concern around the idea of a risk thermostat, whereby taking protective measures in one area means that people feel greater license to take risks in another. Obtaining a face mask may make people feel more protected and could mean they make less of an effort to wash their hands adequately. Empirical evidence on this point would be very useful.

Taking protective measures in one area may make people feel greater license to take risks in another. . . A face mask may make people feel more protected and could mean they make less of an effort to wash their hands.

Awareness is unlikely to be enough on its own. We also need to consider availability. In some instances, there are practical barriers to handwashing—water, soap, and drying materials may not be available. People may be aware of what they should do but be unable to follow through. One obvious solution is to increase the provision of alcohol-based hand sanitizer dispensers at locations where handwashing is infeasible. Doing this has been shown to improve hand hygiene on its own.

However, behavioral science shows that not all “availability” is equal: even small increases in required effort may result in a hand sanitizer going unused. Therefore, those providing hand sanitizer should also consider whether they’ve made usage as convenient as possible. How can dispensers be located so people do not have to make detours to use them? How can the dispensers be made more prominent—like the use of color? Where do people normally have to pause, thus making them more open to usage—like waiting for an elevator?

This leads to the final point: people may not wash their hands even if they’re aware of the benefits and the option is available. They may be busy, tired, or simply have to do it too often for full compliance. This is a prime example of the intention-behavior gap. While we may have an intention to wash hands, the immediate context may mean we do not follow through.

Sometimes this intention-behavior gap can be reduced by introducing prompts or reminders at the moment handwashing is needed. One study tested the effect of placing different messages by the soap dispensers in the restrooms of a highway service station in England. The researchers then installed wireless devices to measure soap use. The most effective messages increased the use of soap by 10 percent, but effects varied by gender: messages focused on how soap kills germs worked best for women, whereas men responded to those that triggered disgust. (Gender seems to be an important factor for handwashing in general.)

Perhaps the most effective and sustainable tactic is to make the behavior habitual. Habits are actions that occur without a conscious decision when we encounter a particular situation or cue. A survey of 12,000 households found that washing hands with soap was more likely when handwashing was an “automatic” behavior. The advice to sing “Happy Birthday” twice while washing hands to reach the 20 seconds required to remove viruses implicitly recognizes the value of habit: since this song is so familiar to us, it is likely to proceed automatically to completion once started.

The new U.K. government handwashing poster links handwashing with three regular activities: getting home or into work, blowing your nose, and eating or handling food.

Another promising route is for public health communications to help people link handwashing with common events. For example, the new U.K. government handwashing poster, which BIT helped to develop, explicitly links handwashing with three regular activities: getting home or into work, blowing your nose, and eating or handling food. But we should also help our friends and family create handwashing cues that work for them and their everyday routines.

Handwashing can be hard, but it’s also vital. The cause for hope is that individuals do have the ability to increase handwashing in our homes, workplaces, and elsewhere. But this can only happen if we use behavioral science to be realistic about the physical and mental barriers people face, rather than just admonishing them to do the right thing. If we focus attention on handwashing, tweak the environment to make it as easy as possible, and build new habits by linking washing to existing behaviors, we can take advantage of one of the most effective measures to prevent the spread of viruses.

Updated: This article was updated April 15, 2020 to reflect the new recommendations around face masks.