New cases of Covid-19 in the United States rose 5% to more than 450,000 last week, the third week in a row that infections have increased, according to a Reuters analysis of state and county data.
The average number of Covid-19 patients in hospitals rose 4% to more than 37,000 in the week ended April 4, breaking a streak of 11 weeks of falling admissions.
Health officials have expressed concerns about the increase in travel around the Easter holiday and school spring breaks, at a time when more infectious variants of the coronavirus are circulating.
While flu viruses tend to be seasonal, with cases falling as the weather warms, health officials said they have not seen similar trends with the novel coronavirus, pointing to a surge in Covid-19 cases in some regions last summer.
"I don't think we should even think about relying on the weather to bail us out of anything we're in right now," Dr. Anthony Fauci, the nation's top infectious disease expert, said at a news briefing on Monday.
Twenty-seven out of 50 states reported increases in new cases last week compared with the previous seven days, according to the Reuters analysis.
Per 100,000 people, Michigan, New Jersey and New York reported both the highest number of new cases and the highest number of hospitalizations.
Deaths from Covid-19, which tend to lag infections by several weeks, fell 17% to about 5,800 last week, or about 834 per day. Health officials have said the country's vaccination effort could limit deaths even with rising cases.
For a sixth week, vaccinations set a record, with an average of 3.1 million shots given per day last week. As of Sunday, 32% of the US population has received at least one dose and 19% was fully vaccinated, according to the CDC.