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New COVID-19 model shows little benefit in vaccinating high-risk individuals first

To obtain significant improvements, a very large fraction of a town's population should be vaccinated.

Jeff Lagasse, Associate Editor

Since the development of vaccines for COVID-19, the priority has been to get it into the arms of high-risk individuals first, in an effort to control a still-raging pandemic. Evidence, however, suggests that this may have only a minimal impact on coronavirus deaths.

The World Health Organization reports that as of January 19, there have been about 94 million cases of COVID-19 globally, with more than two million deaths. In the face of these numbers – driven in part by an aggressive resurgence of the virus in the U.S. – health authorities face a tenuous balancing act: how to enact policies to keep citizens safe while doing the least possible damage to quality of life and local economies. 

This is especially an issue in smaller cities and towns, where a short supply of intensive care units and tight budgets make the thin line between precautionary measures and normalcy even thinner.

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A new theory and simulation platform that can create predictive models based on aggregated data from observations taken across multiple strata of society could prove invaluable.

Developed by a research team led by Maurizio Porfiri, institute professor at the NYU Tandon School of Engineering, the novel open-source platform comprises an agent-based model (ABM) of COVID-19 for the entire town of New Rochelle, located in Westchester County, New York.

In the paper "High-Resolution Agent-Based Modeling of COVID-19 Spreading in a Small Town," published in Advanced Theory and Simulations, the team trains its system, developed at the resolution of a single individual, on the city of New Rochelle – which had one of the first outbreaks registered in the U.S.


The ABM replicates, geographically and demographically, the town structure obtained from U.S. Census statistics and superimposes a high-resolution – both temporal and spatial – representation of the epidemic at the individual level, which considers physical locations and unique features of communities like human behavioral trends or local mobility patterns.

Among the study's findings are those suggesting that prioritizing vaccination of high-risk individuals has only a marginal effect on the number of COVID-19 deaths. To obtain significant improvements, a very large fraction of the town population should, in fact, be vaccinated. 

Importantly, the benefits of the restrictive measures in place during the first wave greatly surpass those from any of these selective vaccination scenarios. Even with a vaccine available, social distancing, masks and mobility restrictions will still be key tools to fight COVID-19.

The team pointed out that focusing on a city of New Rochelle's size was crucial to the research because most cities in the U.S. have comparable population sizes and concentrations. 

Supported by expert knowledge and informed by officially reported COVID-19 data, the model incorporates detailed elements of pandemic spread within a statistically realistic population. Along with testing, treatment and vaccination options, the model also accounts for the burden of other illnesses with symptoms similar to those of COVID-19.

Unique to the model are the possibilities of exploring different testing approaches (such as in hospitals or drive-through facilities) and vaccination strategies that could prioritize vulnerable groups.


As of January 13, the federal government, under the Trump Administration, said it would no longer hold back doses of the Pfizer and Moderna vaccines for the second booster shot needed for immunization.

There is enough of a supply from the pharma manufacturers to get more people vaccinated, while still ensuring that those who have already received the first dose of the COVID-19 vaccine will be able to get their second dose, according to former Health and Human Services Secretary Alex Azar. However, Azar later admitted that there is no stockpile of reserve doses.

Nearly 38 million doses of the COVID-19 vaccine, including 25 million first doses, have been made available to states to order, and more and 9 million vaccinations had been given as of mid-month. 

The bottleneck is in getting vaccines into arms. States had been holding back supply to make sure there is enough for the second dose, which is required 21 to 28 days after the first dose, depending on which vaccine is administered. 

Twitter: @JELagasse
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