City officials are tracking a significant uptick in COVID-19 transmissions and hospitalizations in the past few days, mirroring an alarming trend in the state that Mayor Walsh warned today could be worse than last spring’s peak in the crisis.

On Thursday, the mayor said, there were 418 confirmed positive cases in Boston, up from 407 the previous day.

“The feeling that I’m getting here is that these numbers could exceed what we saw in April and May,” the Mayor told reporters outside of Boston City Hall today. “Most of these cases where people are getting sick they went traveling for the holidays and didn’t realize they had the virus. By Tuesday we could be building a field hospital, or we could be talking about numbers getting better in this region. This virus is still deadly.”

Boston recorded 825 new COVID cases in the last two days and Wednesday’s number for Massachusetts was the highest since the pandemic began.

“We’re also seeing more patients being admitted to hospitals,” the mayor added. “Since Friday we’ve seen an increase of about 70 patients, and yesterday 5 patients were moved into intensive care unit beds.”

Dorchester, East Boston, and Hyde Park remain the neighborhoods with the highest positivity rate, Walsh said. Data published on the Boston Public Health Commission’s website for the week ending on Nov. 26 shows the following positivity rates for Dorchester and Mattapan: Dorchester 02122/02124 14.9 percent; 02121/02125 15.8 percent; Mattapan 11.5 percent.

An average of 4,570 tests were recorded daily last week.

“That number is down a little bit from the previous week,” said Walsh, adding that the city is seeing fewer tests than in the week leading up to the Thanksgiving holiday; and that the average number of positive tests daily was 195.

“We’re seeing increases virally around all types of different activities and we’re seeing people getting seriously ill,” Walsh told reporters. “We’re going to be monitoring this data closely and looking at what resources we can bring as a city and working with the hospitals.

“In the meantime, we need to work together to get these numbers down. We need to be serious about this virus. We’re asking people to follow the public health guidelines at home and in the workplace If you are an employer— there should be no eating in common areas and allow people to work from home as much as possible.”

The mayor advised Bostonians over the age of 65 or those experiencing health complications to take extra care and stay home as much as possible.

“I think if you’re over 65 you shouldn’t be in a restaurant and you shouldn’t go to certain spaces,” he said. “That’s been a consistent message since the beginning of COVID-19. People have to make a judgement call on that and be very careful,” he said. “And it's not just [for those] over 65, if you have health issues or breathing issues you shouldn’t put yourself on in those situations either. It’s a personal call right now, to put yourself in a situation that you don’t want to be in to get this virus.”

Walsh urged anyone who travelled for Thanksgiving or attended group gatherings to be tested again. He also invited representatives from Marine Toys for Tots, Greater Boston, to speak about their upcoming holiday drive.

“This is a very cautious time but we have taken precautions to revive volunteers safely and make sure everyone is checked before they volunteer this year. Anything that can be provided this year in terms of monetary or toy donations would be greatly appreciated,” said Howard Brown, marine staff sergeant.

Volunteer numbers are much shorter this year, which Brown called “very understandable” given the public health risks.

“During the next 3 months we need to come together. We’re stronger together than we are apart and I just ask that whatever is able to be donated— don’t be afraid we’re doing all we can to be safe and know that what you do is not in vain there is a family member that greatly appreciates it.”

Brown said there is a big demand for toys for girls age 7 and up. Walsh added that the group needs financial investments and donations.

When asked about his concern given the sharp rise in covid numbers, Walsh said said: “I think when I get the numbers for today, if we are in the 400 range I’m going to be very concerned. We had two weeks of lowering numbers and I was encouraged by that. The daily numbers were down to around 185. Four days ago we were talking about keeping restaurants open and possibly opening schools and today it’s in the back of our minds— what happens if these numbers continue to go up.”

“The biggest part of my concern is coming from the number of hospitalizations going up,” he added.

Marty Martinez, chief of Health and Human Services for the city, said city officials are working in coordination with the state on their efforts around planning for the eventual rollout of COVID vaccines.

“The federal government has started to release some guidelines on prioritization that will be passed down to the state,” said Martinez. “Right now the state is in the process of finalizing their own plan of how distribution will happen to the federal government. The local board of health and the local effort of our city is to make sure that we mobilize the community to want to get the vaccine and build trust in the vaccine.

“It will be an important piece to make people realize that it is safe, it has been tested and we need to make sure we’re communicating that,” Martinez said.