The risk of West Nile virus infection in Cambridge was raised to “moderate” from “low” on Thursday after positive-testing mosquitoes were detected in Somerville, Boston, Brookline and Waltham.

The city is making a concerted push to overcome parental reluctance and get children under 5 vaccinated against Covid-19. “What we feel like we’re dealing with at this point is [a] resistance to take their children to be vaccinated,” chief public health officer Derrick Neal told city councillors.

Police are asking the public’s help in finding a missing 70-year-old Cambridge man with dementia who was reported missing Wednesday evening.

City officials are trying to deal with sudden and drastic changes in federal guidelines for assessing risk of Covid-19 transmission at the same time they plan to eliminate the indoor mask mandate. The combination left city councillors without a clear explanation for decisions on mask requirements.

The omicron surge may have peaked in Cambridge with overall case numbers plummeting, and the city’s public health experts have started to talk about a next, less crisis-driven phase of dealing with Covid. Yet more residents are dying of Covid-19, and more elders living in nursing homes and assisted-living centers are getting infected.

Cambridge’s Covid-19 case rate apparently has peaked and is plunging as fast as it shot up in December, similar to the trend statewide. Yet the rate is still higher than at any time before the latest surge. And cases in long-term care and deaths have been rising while hospitals remain full.

Public meetings this week look at bike lanes and Alewife offices and labs; Lamplighter Brewing and the return of the Indian restaurant Tanjore; how universal pre-kindergarten is being developed by the city and school district; and more.

About 72 percent of fully vaccinated Cambridge residents 65 and older have received a third shot, according figures reported by the city for the first time Thursday, as 391 new cases of Covid were reported. The cases strained hospitals, nursing homes and even a library branch that will be closed for nearly a week.

Almost all staff who care for vulnerable residents at Cambridge’s three nursing homes are fully vaccinated against coronavirus, but less than one-third of eligible employees have received a booster shot in two facilities.

The city reported a record 143 new Covid-19 cases Thursday, the highest one-day increase since the pandemic began in March 2020. The Cambridge Public Health Department said 53 percent of new cases in the two days on Wednesday and Thursday were residents in their 20s; another 16 percent were people younger than 20.