The increase, epidemiologists say, is likely caused by the change of seasons, with colder weather pushing people inside and causing them to close windows, increasing the risk of transmission. Cold, drier air can also benefit the coronavirus by helping viral particles survive and stay in the air longer.
Vacation trips and gatherings could also speed up transmission.
A disease model from a team at New York University’s Grossman School of Medicine, which predated Omicron, predicted around 10 deaths per day in Delta in the coming weeks, according to a team member, Dr. Ronald Scott Braithwaite, professor at NYU and a city councilor. Earlier this year, at the height of last winter’s wave, there were as many as 98 deaths from Covid-19 in a single day.
In New York City, the Delta variant is expected to result in only a slight increase in cases. But it creates a potentially dire situation in western New York City, where last week the number of coronavirus patients admitted to hospitals in a single day – 120 on November 26 – was the region’s highest since start of the pandemic.
Monitoring and testing systems are strong
As new forms of the virus began to emerge across the world earlier this year, New York City began to tinker with its own surveillance system. Turning to universities, hospitals and other labs, the city has set out to analyze at least 10 percent of coronavirus cases in New York City for mutations.
The Pandemic Response Lab, a private start-up that opened its doors last year, quickly became a major player in this effort. Earlier this year, it was sequencing – examining genetic material for mutations – hundreds of coronavirus cases each week and offering information on how different variants were circulating in the city.
The coronavirus pandemic: what you need to know
About 15% of confirmed Covid-19 cases in the city are sequenced, a number some epidemiologists hope to increase. Over the past few months, just about all virus samples analyzed in genome sequencing machines have turned out to be the Delta variant, said Dr Jon Laurent, who oversees the Pandemic Response Lab’s sequencing program.