THE NUMBER of Massachusetts communities considered high-risk for COVID-19 jumped 57 percent over the last week, with more than a third of the municipalities on the Baker administration’s color-coded map now emblazoned in red.

The number of communities in red – considered high risk because they had more than 8 cases per 100,000 people over the previous two weeks – rose from 77 last week to 121 this week. Six of the communities – Bridgewater, Chelmsford, Fairhaven, Kingston, North Andover, and Somerset — were assigned asterisks, meaning the spread of COVID-19 was considered less because a large chunk of their infections occurred at a prison, long-term care facility, or a college.

The state as a whole saw its case count per 100,000 people rise to 11.8 from 9.2. The count was 4 two months ago.

The state rate now exceeds one of the thresholds Massachusetts is using to help determine other states that are higher risk. Visitors from states with more than 10 cases per 100,000 people are required to fill out state forms and either quarantine for 14 days or provide proof of a negative COVID-19 test. The threshold had been set at 6 cases per 100,000 until October 16.

On the Baker administration’s color-coded map, the eastern half of Massachusetts is now colored almost entirely in red and yellow. Yellow is the designation for moderate risk communities, those with between 4 and 8 cases per 100,000. There were 76 yellow communities last week.

Lawrence again was the community with the highest number of cases per 100,000 at 52.8, up from 45.9 last week. Blandford was second at 41.2, Revere at 39.4, Winthrop at 36.4, and Chelsea at 32.6. In all, 16 communities had rates above 20.

The age grouping of cases continued to follow recent trendlines, with the number of cases highest among the youngest age group, those 19 and under, and steadily declining as age rises.

This week’s report said there were two deaths in the 20-29 age group over the last two weeks and zero in the 19-and-under and 30-39 age groups. Of the 266 deaths over the last two weeks, 159, or 60 percent, were in the 80-plus age group.

In an effort to drill down into the settings where infections are occurring, the Baker administration on Thursday began releasing information on COVID-19 clusters.

Households represented the largest cluster category and were defined as two or more cases among people who contracted the virus within 28 days of each other and reside at the same address. The data indicated there were 2,707 clusters from September 27 to October 24 and 3,854 overall. Household clusters accounted for a total of 7,428 cases.

The second largest category was long-term care facilities, where a new cluster was defined as two or more cases in a facility that has not had a case in the previous four weeks. The data indicate there were 59 clusters in long-term care facilities between September 27 and October 24, 141 clusters overall, and 811 total cases.

The third largest cluster category was child care, where a cluster was defined as two or more cases with a common exposure. Child care had 28 clusters between September 27 and October 24, 55 clusters overall, and 78 total cases.

Other categories on the state’s list had fewer clusters than child care but more overall cases. In the period between September 27 and October 24, for example, senior living facilities reported 95 cases, organized athletics and camps 91, places of worship 77, and restaurants and food courts 70. Other clusters were social gatherings (67 cases), hospitals (63), and colleges and universities (38).

With the rise in red communities, a number of them were required to take a step back in the state’s phased reopening plan, dropping from Phase 3 Step 2 to Phase 3 Step 1. The group moving back included Abington, Berkley, Canton, East Longmeadow, Fairhaven, Fall River, Hanover, Hanson, Hingham, Marshfield, Milford, Pembroke, Rockland, Wakefield, and Weymouth.