ITHACA, N.Y. (WSYR-TV) — In one month, Tompkins County went from having one of the lowest coronavirus infection rates in New York State to the highest.

On November 15, only one person tested positive for the virus. On December 15, 387 people tested positive according to data released Thursday by the Tompkins County Health Department.

It represents the county’s single largest one-day increase of the nearly two-year pandemic. It breaks the record high of 344 cases set Sunday. For comparison, last winter’s surge that brought a historic case load to Onondaga County resulted in only 62 cases in Tompkins County.

The county numbers are being blamed on the spread of coronavirus on campus of Cornell University, which pending lab results are expected to show as an outbreak of the Omicron variant.

Two weeks ago Saturday, zero positive tests were detected by the university’s labs. This week, four days have had case loads above 200. Thursday, there were 330 cases.

Professor Christopher Morley, a public health expert at Upstate Medical University, said Cornell University could be considered a “case study” for how a community responds to the new Omicron variant.

“You have a well-vaccinated population of younger and theoretically healthier, less at-risk people, who suddenly who had their case counts spike dramatically,” Morley said in an interview with NewsChannel 9.

Morley says Omicron is challenging the assumptions made based on previous variants of coronavirus. Early indications show it’s more contagious, has evolved to spread easier and is successful at infecting people once considered fully immune with two initial doses of the coronavirus vaccine.

Morley says he’d expect the CDC to raise the “fully vaccinated” status to require a booster shot.

“Even if we assume the Omicron variant leads to less-severe disease for most people,” Morley explains, “the fact that it spreads so rapidly as it did on the Cornell campus means you have many more cases. So a small percentage of people being hospitalized, but much larger number of people getting sick, which still leads to a surge in hospitalization.”