Using a Risk Analysis Framework to Guide COVID-19 Decisions

A young, masked woman sits in the middle chair in a waiting room, with the chairs on either side of her blocked off for social distancing.
Every day of the COVID-19 pandemic requires risk analysis, whether it’s policymakers weighing restrictions to reduce transmission, the local government deciding to reopen in-person schooling, or individuals opting to social distance vs. gather with friends.

Every time you step outside of your home during the pandemic, there’s always the risk that you could get—or give—COVID-19. That’s why using risk analysis principles can be an important strategy to help assess the dangers that exist.

“Risk analysis is a scientific tool that can help us assess threats to human health, provide input into how to manage these risks, and enable us to communicate more effectively with the general public about how best to respond to the threats,” says James K. Hammitt, program director of the Harvard T.H. Chan School of Public Health’s Environmental Health Risk: Analysis and Applications. Understanding how to use risk analysis effectively can be essential for people working in a range of settings, including health care, public health policy, government and regulatory affairs, environmental science, engineering, and much more.

Communicable and Non-Communicable Hazards

“For non-communicable dangers like air pollution, contaminated food, and environmental radiation, a person’s risk is determined by how much exposure they have to the hazard,” Hammitt says. “But for communicable [or infectious] diseases like COVID-19, which are spread from one person to the next, a person’s risk is affected by other people’s behaviors,” he says. For example, when people do not follow safety guidelines such as wearing masks and social distancing, rates of transmission increase. With the high transmissibility and unknown surrounding COVID-19, people’s behaviors have played a large role in the spread of the virus, thus influencing its level of risk.

“For communicable diseases like COVID-19, which are spread from one person to the next, a person’s risk is affected by other people’s behaviors.”

The Need to Assess Risk

Risk analysis provides a valuable framework to help understand the potential dangers of both communicable and non-communicable diseases and weigh the options to help people navigate their choices, Hammitt explains. It includes the following three key steps: risk assessment, risk management, and risk communication.

In fact, with COVID-19 it is clear that how we assess and manage risk is important to guiding policies that reduce disease transmission, especially since people’s actions can have such a strong impact on others. Policies to help slow the spread of COVID-19 include requiring social distancing, quarantines, enforcing mandatory mask rules, closing businesses, testing people to see if they are infected, and performing contact tracing. But Hammitt says that while these actions can be crucial to slowing COVID-19 transmission, thus keeping hospitals from being overrun, they are not a panacea. In fact, such interventions can themselves also have a strong negative impact on people’s overall economic status and emotional well-being. This makes it important for public health officials and politicians to weigh the risks and benefits to determine how best to manage the situation.

Assessing the Risk of COVID-19 Transmission

One way to capture the extent of COVID-19 risk is to assess the risk of transmission. R is the reproduction number that indicates how effectively COVID-19 spreads. It depends on people’s behavior and on how many are susceptible to infection.

“In other words, this number answers the question how many people on average one person with COVID-19 will infect,” Hammitt says. “An R of 2 means that if I get infected, I infect on average two more people. And each of those people infects two more, a total of four. And each of those infects two more, for eight new infections. So with a reproductive number larger than one, the number of infections can grow very rapidly,” he says. “Given that it can take two weeks for someone exposed to become sick, you don’t know immediately that you are infected and may be infectious. That’s why most people don’t lock themselves up immediately. By the time you find out you are infected, you may have exposed a lot of people,” he adds.

“We can estimate how much an action might reduce transmission, then find out how costly or burdensome it would be. Keep in mind that some interventions are costly, but they don’t reduce the risk much. So, you need to weigh each intervention to see if it makes sense.”

Managing Risk: Finding Middle Ground

With so little to go on, Hammitt points out that it’s hard to predict outcomes for COVID-19 or to see into the future. Therefore, he says, it’s important for people to find a middle ground to manage the risks.

“In COVID, there has been a tendency to act like you have to do all or nothing. People feel either you shut down everything or nothing. Some people seem to think that masks are a silver bullet. They believe if you wear a mask, all is okay. If not, nothing is okay,” he explains. But he points out that such thinking is flawed. “Masks obviously reduce transmission, but they don’t eliminate it. They are imperfect,” he says. That being said, just because wearing masks is imperfect doesn’t mean it’s not worth doing. “But it also means if it’s a burdensome thing to do, people may think it’s not worth the burden,” he adds.

The same is true of lockdowns. It shouldn’t be an all-or-nothing proposition. “Some schools are open, some are closed; some people are working from home, while others are working in person. I think there should be variation across communities, since managing the risk for each region will require a different response depending on their circumstances,” he says.

Therefore, Hammitt recommends that policymakers go back to risk analysis to determine the best approach for their constituents and their specific circumstances and risks.

“We can estimate how much an action might reduce transmission, then find out how costly or burdensome it would be. Keep in mind that some interventions are costly, but they don’t reduce the risk much. So, you need to weigh each intervention to see if it makes sense,” he says.

“Early on in the pandemic, there was a lot of talk about how it might be better to take strong action against COVID-19, but some experts felt it would be better to let people develop herd immunity. Whether the latter is a good idea depends on how willing people are to get sick, and how many will die, and how costly it is to try other things,” Hammitt says.

He also points out that people often have the idea that if there is too much uncertainty, they can’t act. “In COVID, early on there were a lot of unknowns about how the virus was transmitted and there was the thought that you can’t do anything until you know more and can evaluate. But that doesn’t make sense. Doing nothing is actually doing something. Every action—or inaction—is a choice,” he points out.

Communicating to Guide Decisions

Once community leaders assess the level of risk that exists and determine how best to manage it, they can play a key role in educating the public through strategic communications about how to respond in the safest way. In order to get people to act, though, you need them to trust that you have their best interests at heart. You also need to understand their decision-making process so you can guide them effectively, Hammitt says.

“The way people make decisions can be described using a two-system model. System 1 is fast and is based on feelings. This is usually our default system. System 2 is analytical and takes more effort and more time, so we can’t activate this system too often,” he notes.

For example, in system 1, someone might make a quick reaction to spend the holidays with family, but would not be thinking the scenario through to consider all of the consequences. Yet they could activate system 2 and think more carefully about how much risk their actions could have. As a result, they might decide not to gather because the chance of harming loved ones outweighs the benefit of getting together.

Another example is the decision about whether to get the vaccine once it’s available for the general public. Some people may be opposed to getting vaccinated, with their gut reaction feeling it could be unsafe. But public health experts can communicate the safety and efficacy of the vaccine and the role immunization will play in stopping the spread of the virus and allowing life to return more to normal. Sharing these detailed facts and analysis can help people activate their system 2 response and might lead to a more thoughtful decision.

“It’s important for people to remember that the choices they make about safety practices, such as wearing masks and social distancing, will have a strong impact on the people around them,”  Hammitt says. When you conduct a risk assessment, weighing the costs and potential outcomes of each action, people will be able to make more educated decisions that hopefully will be better for everyone.

Harvard T.H. Chan School of Public Health offers Environmental Health Risk: Analysis and Applications, which explores the basics of health risk assessment and applications of risk assessment to diverse problems.