Tactics for Reopening the Economy

Study finds a combination of strict COVID-19 policies and ongoing caution are the most successful approaches

By Irving Wladawsky-Berger

A few months ago, MIT Connection Science held it’s annual Sponsors’ Meeting online. The virtual meeting included a number of very interesting presentations. Given its continuing importance, I want to focus my discussion on “Reconnecting Society After a Pandemic,” a talk given by Esteban Moro, visiting professor of Human Dynamics.

Moro started his presentation by showing a slide from this article. The slide illustrates that if we had done nothing, or just relied on soft mitigation and herd immunity to contain the spread of the Covid-19 virus, the number of cases and deaths would have gone up very rapidly— overwhelming healthcare systems around the world. Instead, many national and state governments adopted two distinct sets of actions, the hammer and the dance.

The hammer is the somewhat draconian social distancing policies aimed at containing the spread of the virus, especially in regions like the New York metro area where the number of cases were escalating at a very rapid pace. The dance starts once the spread of the virus has been brought under reasonable control — albeit, at the price of large economic costs and societal disruption. The dance is the longer term effort to keep the virus contained until there’s an effective vaccine while reopening the economy and bringing life as close to normal as possible.

How successful has the social distancing hammer been? Earlier this year, Moro and collaborators evaluated the effectiveness of social distancing policies in the N.Y. metro area by analyzing anonymized geolocation data. They found that N.Y.’s social distancing policies had indeed led to major changes in where people spent their time and how they interacted with each other. As of late March, “distance traveled every day dropped by 70% from a weekend average of 25 miles in February to seven miles.” Moreover, “the number of social contacts in places decreased by 93% from 75 to five,” where social contact is defined as being within 25 meters (82 feet) of each other for at least five minutes, and the number of people staying home the whole day increased from 20% to 60%.”

In his “Reconnecting Society” talk, Moro explained the research being pursued by a team of 14 collaborators from around the world to understand the kinds of dance policies that will allow restarting the economy and getting back to a more normal lifestyle.

The research team built a model that allowed them to explore different strategies for the lifting of social distancing interventions in conjunction with testing, the isolation of those who test positive, and the tracing and quarantining of their exposed contacts.

Using the model, they compared the impact of different mitigation and containment strategies aimed at minimizing the risk of additional pandemic waves while providing an acceptable trade-off between economic and public health objectives.

“ COVID-19 has required the implementation of severe mobility restrictions and social distancing measures worldwide,” wrote the team in “Modelling the impact of testing, contact tracing and household quarantine on second waves of COVID-19,” a recently published, peer reviewed paper on their research. “While these measures have been proven effective in abating the epidemic in several countries, it is important to estimate the effectiveness of testing and tracing strategies to avoid a potential second wave of the COVID-19 epidemic.”

To do so, the team analyzed the impact of various social distancing, testing, contact tracing and quarantine policies using anonymized, privacy-enhanced data from mobile devices in the Boston metropolitan area, as well as socio-demographic and census data. As was the case with the earlier social distancing analysis in the N.Y. metro area, the Boston mobility data came from Cuebiq, a geolocation-based intelligence and measurement company, and in particular, from Cuebiq’s Data for Good initiative which makes its data available for academic research and humanitarian programs.

“We find that enforcing strict social distancing followed by a policy based on a robust level of testing, contact-tracing and household quarantine, could keep the disease at a level that does not exceed the capacity of the health care system,” said the team.

Their recent paper and accompanying supplementary material explains their models and analytical methods in great detail. Let me briefly summarize their findings and recommendations.

The overriding finding is that gradually removing the restrictions imposed by social distancing could lead to a second wave with the potential to overwhelm the healthcare system if not combined with strategies aimed at the prompt testing of symptomatic infections and the tracing and quarantining of as many of their contacts as possible.

On the other hand, “Our results indicate that after the abatement of the epidemic through the ‘stay at home’ orders and halt to all nonessential activities, a proactive policy of testing, contact tracing and contacts’ household quarantine allows the gradual reopening of economic activities and workplaces, with a low COVID-19 incidence in the population and a manageable impact on the health care system.”

These findings are based on the analysis of two distinct scenarios for reopening the economy.

Lift. Stay-at-home and social distancing policies are lifted after eight weeks by reopening all work and community places, except for mass gathering locations like restaurants and theaters whose partial reopening stays enforced for an additional four weeks. Models show that in this scenario, resurgence of the epidemic and a second COVID-19 wave are inevitable.

Lift and enhanced tracing: The stay-at-home order is lifted as in the previous scenario, but is now accompanied by a proactive policy of testing and contact tracing. Those who test positive are isolated at home, and their household members and contacts are successfully quarantined for two weeks. The models show that such a proactive policy allows for the gradual reopening of economic activities and workplaces, with a low COVID-19 incidence in the population and a manageable impact on the health care system. “Assuming the identification of 50% of the symptomatic infections, and tracing of 40% of their contacts and households, only about 9% of the population would be quarantined at any time.”

While 9% is still a significant fraction of the population to have to quarantine, this is a much better option when compared to the more massive social distancing hammer policies first deployed to contain the escalating spread of the virus. Moreover, in his presentation at the MIT online meeting, Moro showed that tracing 20% of the contacts of those infected— while not as effective as 40% contact tracing — will still work much better than not tracing contacts at all, as long as contacts who test positive and their household members quarantine for two weeks.

Recent data from across the country has shown the validity of these findings and recommendations. The same modeling methods can be used to evaluate reconnecting and reopening strategies for any other cities and metropolitan areas as long as similar data is available.

This blog first appeared August 15 here.

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