In a new study, researchers have developed a model to simulate the impact of different physical distancing strategies on the spread of SARS-CoV2, the virus that causes COVID-19.
They found that age-specific shelter may be just as effective as population-wide shelter—as long as everyone not sheltering in place also practices safe physical distancing.
This means rather than put the burden of sheltering in place on society as a whole, if some percentage of a specific age group were to stay home and everyone else practice physical distancing, the epidemic could be mitigated until a vaccine is developed.
The research was conducted by a team from the Harvard John A. Paulson School and Engineering and Applied Sciences and elsewhere.
Even as the death toll from COVID-19 continues to rise around the world, many cities and states in the U.S. and other countries are beginning to ease restrictions and develop policies to re-open economies and communities.
Part of what the team wanted to demonstrate through this work is what might happen if people only enforce sheltering for one segment of the population and let others engage in a partial return to normalcy—while simultaneously doing their part to “flatten the curve” by physically distancing in offices, restaurants, and so on.
The researchers developed an individual-level model for SARS-CoV2 transmission based on demographic data including age and household structure and, using that information, created population simulations for COVID-19 hotspots Hubei, China, and Lombardy, Italy.
Using these simulations, they were able to play out different policy scenarios and observe the impact on the virus.
The researchers played out their simulations in Lombardy, which was in the midst of the outbreak during the research.
The researchers modeled the effect of either 50% or 100% of single age group sheltering in place while the rest of the population went about business as usual, with no physical distancing.
They found that even sheltering in place by everyone within a single age group left at least 60% of the population infected. If only 50% of that age group sheltered, nearly 70 to 80% of the population would be infected.
However, combining a single age group shelter-in-place policy with physical distancing by the rest of the population led to an infection rate below 50% and a substantial decrease in the total number of deaths.
In this scenario, there was little difference between 100% of an age group sheltering and 50% of an age group sheltering.
The researchers also found that the most at-risk age groups, people age 70 or older, don’t necessarily need to be the ones sheltering.
In fact, the researchers found that in Lombardy, the most effective policy would have 50% of people 30 to 49 shelter in place and everyone else practice physical distancing.
The team says people in the 30-to-49-year-old-demographic have some of the largest social circles and those circles tend to be intergenerational.
They have kids, go to work, take care of their parents, go out with friends and colleagues.
So, targeted salutary sheltering of this age group combined with the physical distancing of the general population may be enough to thwart a substantial number of cases and deaths.
The researchers proposed that physical distancing from the rest of the population includes policies such as staggered work schedules, increased spacing in restaurants, and prescribed times to use the gym or grocery store.
One researcher of the study is Milind Tambe, the Gordon McKay Professor of Computer Science at SEAS.
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