A new mask mandate went into effect Monday in New York.
CNN  — 

It has been exactly a year since the first Covid-19 vaccination shots, but rising case numbers and hospitalizations are leading cities and states to introduce new mandates and restrictions.

In California, masks will be required in indoor public settings for a month starting Wednesday.

New York Gov. Kathy Hochul last week announced a new, temporary indoor mask mandate that went into effect Monday. It requires everyone in the state to wear a mask in all indoor public spaces unless businesses implement a vaccine requirement. It will be in place until at least January 15.

Starting January 3, you will need to have proof of being vaccinated to get into a Philadelphia restaurant, theater and other entertainment venues where food or drinks are served.

New York City is expanding its “Key to NYC” program that began earlier this year with vaccine mandates for some indoor activities, including eating in restaurants and going to movie theaters.

As of Tuesday, children in the city will have to show proof of vaccination to get into those venues, and starting December 27, people who are 12 and older will be required to show proof of two vaccine doses instead of one, except for those who got the Johnson & Johnson vaccine.

And all private sector employers in New York City will be required to implement a Covid-19 vaccine mandate by December 27, Mayor Bill de Blasio said Monday, meaning anyone who works in the city will be subject to a vaccine mandate.

“We need to take very bold action. We’re seeing restrictions starting to come back. We’re seeing shutdowns,” de Blasio said. “We cannot let those restrictions come back. We cannot have shutdowns in New York.”

Vaccine mandates work, de Blasio said this week.

“Since I put mandates in place in New York City, starting in August, we’ve seen over 1 million more doses,” the mayor said on CNN’s State of the Union on Sunday. “Seventy-one percent of our people fully vaccinated. A lot of those people made the decision because the mandate was there, and it was the thing that moved them, and it’s keeping people alive.”

Even with 60% of Americans now fully vaccinated, Covid-19 cases are again soaring in some places, spurred by the fast-spreading Delta variant. The average number of new cases each day is 49% higher than it was a month ago, according to Johns Hopkins University data, and hospitalizations are 42% higher.

“We’re dealing wth a much more formidable virus in every respect,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases told CNN’s Jim Sciutto, speaking about the Delta variant.

And the even faster-spreading Omicron variant, which had been identified in at least 32 states as of Monday, is on the rise.

In New York City, the daily average of new cases over the last week are 47% higher than the average over the last 28 days, according to the city’s data.

California is also seeing a 47% increase in case rates across the state since Thanksgiving, according to California Health and Human Services Agency Secretary Dr. Mark Ghaly.

That state’s new mask mandate will cover about 50% of the population that lives in counties that don’t have a similar policy, Ghaly said Monday.

Some of the more populous counties in the state, including the Bay Area counties of Los Angeles, Yolo, and Ventura, already have an indoor masking mandate in place.

“Even a 10% increase in indoor masking can reduce case transmission significantly,” Dr. Ghaly said.

Vaccine requirements to enter restaurants and other public settings are already in place in a number of cities around the country, from New Orleans to San Francisco and Seattle.