That’s what happened after July 4, said Megan L. Ranney, an emergency physician and public health researcher at Brown University. She said a jump in positive tests began between two and four weeks after the holiday, suggesting that many were pass-along infections.
The American Automobile Association forecast that about 50 million people would travel for Thanksgiving. Even if only 1 percent caught the virus, Dr. Ranney said, “that’s an extra 500,000 infections in one day,” and they could infect untold thousands more before showing up in the statistics. “We are looking at an exponential effect,” she said, one that would only truly be seen around Christmas and New Year’s Eve. “It will be a double whammy.”
Lewis S. Nelson, chair of the Department of Emergency Medicine at Rutgers New Jersey Medical School, said he was not certain that Thanksgiving travel and gatherings would create a widespread surge in new cases. The virus has been tricky, he said, and predicting the numbers can be extremely difficult.
“We keep saying we’ll see a bump, but most of these events don’t seem to really materialize into something really concerning,” Dr. Nelson said. “Sometimes what you expect to happen doesn’t happen.”
Even so, he said, “my gut tells me we should remain concerned and attentive.”
Dr. Nelson said his hospital in Newark, N.J., was overwhelmed in April, but is manageable now, even though the state is reporting many more new cases. He said there were currently about 30 coronavirus patients, compared to more than 200 in April, a drop he and his colleagues were still puzzling over.
“Just the whole fact that we are not experiencing April right now is inexplicable at this point,” he said. “People haven’t changed. A lot of us believe maybe the virus has.”
Officials were trying to make sure that any Thanksgiving exposure would be reflected in the data. On Monday, Mayor Bill de Blasio of New York City urged residents who had ignored official guidance and attended Thanksgiving gatherings to get tested.