Computer Modeling: Anticipating Rise and Fall of Pandemic’s Waves

Jeffrey Shaman, PhD, a leading infectious disease modeler, has closely tracked the COVID-19 pandemic since its early days. His models have uncovered the dynamics underlying the virus’s spread and helped anticipate its rise and fall with successive waves.

But as the world begins its third pandemic year, much about the future remains unknown, says Shaman, professor of environmental health sciences in Columbia’s Mailman School of Public Health.

Infectious disease models use past and present data to estimate future scenarios, including potential demand on emergency rooms. Shaman works with government officials to guide policy on such issues as masking and school closures. When omicron swept the country late last year, his models accurately projected a peak in cases by the middle of January

The mathematics underlying these models is similar to what is used in weather forecasting. Like maps that project a hurricane’s path, models of SARS-CoV-2 have a “cone of uncertainty,” he says.

Beyond a couple of weeks, predictions are an educated guess. Omicron will continue to recede, but the next pandemic wave could happen as soon as this spring or perhaps not at all.

Optimistically, the virus may have already reached the limit of its ability to create new, immune-escaping variants. People might instead see recurring seasonal outbreaks of alpha, delta, and omicron variants, against which vaccines are effective. For most people, the result could be a mild wintertime illness.

But from the start, COVID-19 has confounded experts. Shaman cautions there is no guarantee the virus won’t continue producing new, highly problematic variants for the foreseeable future.

The pandemic isn’t over, and more than a third of the world hasn’t received a single dose of the vaccine. “This virus may still have some tricks up its sleeve,” Shaman says.