But when the researchers combed through the electronic health records of nearly 5,000 people, all over the age of 65, who were hospitalized for Covid at a dozen Northwell hospitals in March and April of 2020, they found that one-third had arrived with other symptoms, unexpected ones.

The team, searching through records using language software, found that about one-quarter of older patients reported a functional decline. “This was falls, fatigue, weakness, difficulty walking or getting out of bed,” Dr. Marziliano said.

Eleven percent experienced altered mental status — “confusion, agitation, forgetfulness, lethargy,” she said. About half the group with atypical symptoms also suffered from at least one of the classic Covid problems — fever, trouble breathing, coughing.