Chief public health officer Derrick Neal speaks Monday with city councillors in a meeting video screen capture. Nearby is City Manager Louis A. DePasquale.

Cambridge reached a milestone of sorts on Thursday: The city has now recorded more than 10,000 cases of Covid-19 among its residents since early March 2020. The Cambridge Public Health Department reported 220 new infections on Thursday – another daily record – to bring the total to 10,141 cases.

Though the health department hasn’t said the new omicron variant is driving the rise in cases here, that Covid-19 variant – the most contagious yet – dominates infections in Massachusetts and nationwide. Scientists say there’s evidence it causes less severe illness than previous variants, but they’re not sure.

It took about a year to exceed 5,000 cases in the city, after a lull in the summer of 2020 and a surge last fall and winter. After another quiet summer this year, cases started rising in the fall, spurred by the delta variant. In the past six weeks, as omicron started taking over, the total has risen by about 2,000 cases.

In daily email updates as cases rise and the holidays approach, the city health department has urged residents to take increasingly stringent precautions against infection. On Thursday, health officials suggested that people skip crowded indoor events with poor ventilation and stay home if they are vulnerable or live with people who are, such as elders, or if other people at the gathering aren’t vaccinated and boosted and won’t consistently wear masks.

The department said if people decide to go to an event or host it, they can ask guests to take a rapid Covid-19 antigen test beforehand, but even if the results are negative they should wear masks and physically distance. Health officials also urged hosts to open windows or use fans to increase ventilation and to ask guests not to sing or talk loudly even if masked.

City Manager Louis A. DePasquale has said he’s considering whether to follow the lead of Boston and surrounding communities in requiring people to be vaccinated to go into restaurants and health clubs. City councillors want him to impose the rule.

Though omicron illnesses may be less severe, the variant is causing so many infections that hospitalizations are rising nationally and in Massachusetts. Massachusetts hospitals are under stress from increasing demand from Covid patients and others who delayed care earlier in the pandemic, while the state has said 500 hospital beds statewide can’t be used because of staff shortages.

Gov. Charlie Baker ordered hospitals on Tuesday to postpone elective procedures that will likely lead to admissions. Cambridge’s two hospitals, CHA Cambridge Hospital and Mount Auburn Hospital, have said they are full and they are taking steps to carry out Baker’s order.

Experts say unvaccinated people are most at risk from omicron. Still, there’s evidence that two shots of the Pfizer or Moderna vaccine, and one shot of Johnson & Johnson, provide reduced protection against the variant, and health officials advise people to get a booster shot for more defense. The Cambridge Public Health Department says it hasn’t received data from the state on how many residents have received boosters.