Cases of COVID-19 and associated deaths were more prevalent in Connecticut's for-profit nursing homes, as well in larger facilities and homes that are part of chains and located in communities with high infection rates, according to a preliminary, third-party review released Tuesday.

The report from the Princeton, N.J., research firm Mathematica reviewed how the state, nursing homes and assisted living centers prepared for and responded to the coronavirus pandemic. It found that early responses to the coronavirus outbreak were “undermined" by gaps in scientific knowledge about the how the virus spreads, the factors that put people at risk and the range and severity of symptoms — especially among older people.

“Like much of the country, Connecticut long-term care facilities were hit hard by COVID-19," said Patricia Rowan, researcher at Mathematica and the project’s director, in a written statement. “Our preliminary assessment of the state’s response found that state officials made policy decisions and issued guidance based on the available knowledge at the time from national and state epidemiologists and public health experts, but that knowledge was undermined by gaps in the scientific understanding of the virus.”

For-profit nursing homes in Connecticut had about 60% more cases of COVID-19 and associated deaths per licensed bed than nonprofit facilities in the state, while nursing homes that are part of a chain had about 40% more cases and deaths than independently owned facilities, according to the research.

Prevalence of COVID-19 in nursing home's surrounding community was a “major predictor” of a facility's infection rate. Nursing homes with the most cases per licensed bed tended to be located in cities and towns that also had the most cases per 100,000 residents, Mathematica determined.

In June, Democratic Gov. Ned Lamont ordered the review, which included input from the operators of the long-term care facilities, unions representing the workers, patients, family members, health experts and others. A final report is expected in September.

More than 3,000 residents of nursing homes and assisting living have died of COVID-associated causes during the pandemic in Connecticut. That represents about 74% of state's total deaths from COVID-19. Adults over age 85 were the most severely impacted.

Some state legislators criticized the report for not offering much new information. The state spent about $450,000 in federal coronavirus funding on the review.

“I’m not sure how comprehensive the study was given some of the conclusions that we heard today,’’ House Republican Leader Themis Klarides of Derby said following a morning briefing. “The consultant offered some pretty basic findings that seem fairly obvious.’’

Researchers at Mathematica also released a series of recommendations for Connecticut as the state and long-term care facilities prepare for a possible second wave of infections this fall. For example, they urged state officials to revisit its guidance to long-term care facilities regarding the frequency of testing. Currently, testing of residents and staff stops when there have been no new cases for 14 days.

The report warns that practice “might inadvertently miss asymptomatic spread of COVID-19." Also, the report suggests broader testing of those who previously tested positive might be necessary given new evidence that's emerging about how long immunity might last.

While the report doesn't recommend the blanket lifting of Connecticut's current ban on indoor visitations at long-term care facilities, researchers recommended balancing such strict measures with the psychological needs of residents. Various advocacy groups and family members have raised concerns about how residents of nursing homes are being harmed emotionally by not having had inside visits since mid-March.

Currently, only limited outdoor visits, window visits and virtual visits are allowed to help stop the spread of the virus.

The report recommends that the Department of Public Health come up with “objective criteria” based on the amount of infection in a particular community to help guide facilities as they eventually reopen and allow in-person visitations.