Study Shows Which COVID-19 Policies Are Most Effective

When the COVID-19 pandemic first began, officials scrambled to enact policies to limit the spread of the virus. Now, a new study analyzes which policies are the most effective—and which haven't been very helpful.

The study, which was published in PLOS One in December, analyzed the effectiveness of COVID-19 control policies in 40 different areas, including several countries and states in the U.S.

The researchers used a model to generate estimates of the impact of each policy in an area after looking at the overall portfolio of policies enacted by the jurisdiction, the level they were implemented, how well locals complied, local COVID-19 infections and deaths, and how well these policies performed in other areas.

The researchers examined 11 categories of policies, including:

• School closings
• Workplace closings
• Cancellation of public events
• Restrictions on gatherings
• Closing of public transport
• Stay-at-home requirements
• Restrictions on internal movement
• International travel controls
• Public information campaigns
• Testing
• Contact tracing

Unfortunately, the researchers found that most policies weren’t all that effective. “We find that a set of widely implemented core policies reduces the spread of virus but not by enough to contain the pandemic except in a few highly compliant jurisdictions,” the researchers wrote.

Researchers defined this core group of policies as "socially tolerable" and relatively less restrictive than other policies. They found that most areas need to implement additional COVID-19 restrictions on top of these more socially acceptable policies in order to significantly reduce the spread of the virus.

Study co-author Anita McGahan, PhD, a professor of strategic management and public policy at the University of Toronto, tells Verywell that she and her fellow researchers “wanted to support good decision-making about public policy during the pandemic” with their work. “We each were keenly aware of the economic impact of shutdowns,” she says. “Our hope was to understand how specific policies interacted to control infection.”

The ultimate goal, she says, is “to provide policymakers with insight on which would be necessary to control infection.” Here’s what she and her colleagues discovered.

Most Effective COVID-19 Policies

The team found that the “core group of relatively tolerable policies” dropped the growth of COVID-19 infections across the 40 jurisdictions studied from 270% to 49% per week, McGahan says. Those policies include:

• Canceling public events
• Restricting gatherings to fewer than 100 people
• Recommending staying at home
• Recommending no internal travel
• Implementing a partial international travel ban
• Coordinating information campaigns

“The reduction on average associated with these policies is significant, but it is not sufficient to drive infection growth below zero in all but the top 10% of jurisdictions by compliance,” McGahan says. In 90% of the jurisdictions, she says, more “high-impact policies” are needed to reduce the spread of the virus. They include:

• Targeted or full workplace closings for all but essential workers
• Stay-at-home requirements
• Targeted school closings

“These are hard to tolerate, but because they drive COVID-19 growth below zero, they may be essential for COVID-19 control,” McGahan says.

Least Effective COVID-19 Policies

McGahan’s research found that the following policies were the least effective at controlling the spread of COVID-19:

• Contact tracing
• Testing

“One reason for this may be that tests and contact tracing were not implemented widely in a timely and effective way until late in the pandemic,” McGahan says. While she says these control measures would typically “create actionable insights” that help isolate people before widespread transmission occurs, that hasn’t happened for a few reasons. McGahan cites delayed testing results and difficulty with effective contact tracing as potential issues.

“We need easy access to tests that generate rapid results, and contact tracing that is so effective that it stops disease transmission in its tracks,” she says. 

Overall, McGahan says that more stringent policies make an impact—and it’s crucial that jurisdictions use them to limit the spread of COVID-19. “Controlling disease transmission is going to require the reinstatement of workplace closings and perhaps even stay-at-home orders if we can’t improve compliance with the core policies that are now in place in most jurisdictions,” she says.

Compliance is also an important factor. “Compliance is our way out of these hard-to-tolerate policies,” McGahan says. “Now more than ever, it’s so important that each of us follows the public health guidance on mask-wearing, social distancing, rigorous self-diagnosis, and case reporting. Without high compliance with the core policies, we’re going to face economically tough measures over the next few months that are essential for saving lives.”

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