Boston Mayor Marty Walsh is sounding alarms as COVID-19 infection rates, after months of declines are again on the rise.

Walsh blamed the trend on irresponsible behavior like parties and other unsafe social gatherings as well as a general loosening of safety precautions.

The mayor is warning that if these trends continue, the city could revert to the strict shutdown measures implemented this spring.

“If we don’t start to take responsibility as individuals, we’re going to be in a potential case where I have to stand at this podium and talk about shutting down the city again,” Walsh said.

"I don’t think I have to tell anyone the implications of having to shut down the city of Boston again and the implications of what that would mean to our businesses, our seniors, our constituents, the residents of our city,” Walsh added.

Boston Public Schools is again pushing back plans to allow the next phase of students to return to opt-in-classroom learning, Walsh said.

The mayor is announced stepped up enforcement to combat virus spread and to reinforce safe behavior.

These measures include intensifying efforts by the Boston Police Department and the the public health unit to find and stop house parties, which Walsh said are being held around the city (especially in South Boston) in violation of emergency health orders.

Roughly half of new cases in Boston are among people under 30 years old, Walsh said. He noted the Federal CDC recently published a report suggesting that young people have been a source of COVID-19 spread in several cities.

“What happens is young people get COVID, and a month later you see larger spread in that community or that neighborhood,” Walsh said.

“A month later, the virus is spreading throughout the community, older people are getting it, and more people are in the hospital and more people will eventually die of this virus.

“Time will pass. We will be able to go to parties again,” Walsh said. “But right now, we’re at a very critical point in where we are with coronavirus.”

The mayor is also urging any resident who has been to a party or other out-of-the-house social gathering to get tested.

Residents can find the locations and times for free, walk-in testing sites around Boston on the city’s website.

Census Push

Walsh is also imploring Boston and Massachusetts residents to go online to answer the US Census, if they have not done so already or have not been visited at home by a Census counter.

The return rate for Census questionnaires remains well below the already-low rates seen in 2010, Walsh said, and that could result in an under-count of residents and the loss of potentially millions from crucial federal funding streams.

“The Census count only happens once every 10 years,” Walsh emphasized.

“The Census is how our country determines congressional representation and it’s how billions of dollars in federal funding gets allocated for things like child care, education, food and community health centers, so it’s very important … we get a complete count,” Walsh said.

Walsh criticized the Trump administration for its decision to end the Census tonight, two weeks earlier than the previous deadline.

But Walsh said there is still time to respond online.

“Stop what you’re doing, go online, and respond to the Census,” at My2020Census.Gov Walsh said. “It takes 20 minutes, it’s really easy.”

Residents who don’t have internet access can respond by phone at 844-303-2020.

Walsh also announced the beginning of early voting for the Nov. 3 general election, starting Saturday, Oct. 17 and running through Oct. 30.

There are 27 early voting sites around the city, including Boston City Hall, Walsh said.