Massachusetts may not be ready to open up until June, more than a month after Gov. Charlie Baker is considering ending nonessential business and school closures, experts at Johns Hopkins University say.

Read the full Johns Hopkins report here…

Massachusetts’ stay-at-home advisory does not yet have an end date, but Baker has said schools and nonessential businesses may reopen by May 4, although he has said his administration is considering extending that date.

That’s the advice of the Institute for Health Metrics and Evaluation, an independent global health research center at the University of Washington, which says that June 8 is the earliest Massachusetts should reopen, with the right measures in place to contain the coronavirus.

“Longer is better,” Dr. Christopher Murray, the institute’s director and professor of global health, said in a webinar Friday.

In a new report, the Johns Hopkins Center for Health Security said states should consider initiating the reopening process only when:

the number of new cases has declined for at least 14 days;

rapid diagnostic testing capacity is sufficient to test, at minimum, all people with COVID-19 symptoms, including mild cases, as well as close contacts and those in essential roles;

the health-care system is able to safely care for all patients, including providing personal protective equipment for health-care workers; and

there is sufficient public health capacity to trace people with whom all new cases have come into contact.

The center cautioned, however, that even when states do reopen, people should work from home if possible or wear a cloth mask to work.

Governors should consider reopening in phases separated by two to three weeks, the report said. If coronavirus case counts, hospitalizations and deaths go up in that time, officials should pause further steps in reopening and take measures to get control of the rising numbers, if necessary re-imposing social distancing interventions, the center said.

Bars and large concert and sport venues all have high-contact intensity, the report said, while retailers and shopping malls have low-contact intensity.

“What we don’t want are the conditions that led to us having to stay home in the first place,” Rivers said, “but if cases begin to increase again, there may come a time when we all need to do that.”

Officials should consider modifying public transportation to make it safer, with lower ridership and more spacing between people, the center said.

If schools are reopened, most kids will be at low risk of severe infection themselves, the report said, but some children with underlying conditions will be at higher risk, as will some parents, teachers and staff.

Some parents may elect to not allow their children back in school, the center said, so schools that reopen will need to decide whether to also offer tele-education, the institute said.