Restaurants will be restricted to take-out, schools are shut down and large public gatherings are being banned in an effort to contain the coronavirus before it spreads further in the state.

As of Monday, nearly 20 people in New Hampshire have tested positive for COVID-19, the disease caused by the new coronavirus.

Health officials have said they believe all but one of the state’s cases were infected via international travel, domestic travel or close contact with another patient. The other case is still being investigated. Among the cases announced Monday was a female under the age of 18.

None of them have been hospitalized. For most people, the virus causes mild or moderate symptoms such as fever and cough, and the vast majority recover.

For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia, or death. People with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover, according to the World Health Organization.

New Hampshire is joining other states in restricting restaurants and bars to takeout, delivery and drive-through service in hopes of slowing the spread of the new coronavirus.

Gov. Chris Sununu announced his decision Monday, a day after neighboring Massachusetts made a similar move.

“Knowing neighboring states have closed restaurants and bars has caused New Hampshire to evaluate those states’ actions and their impact on New Hampshire’s population risk profile,” he said in a statement. “This action will help slow the spread of this virus in New Hampshire. We do not take this decision lightly. This will be hard, but we are all in this together.”

Other places with similar restrictions include Rhode Island, Illinois, Ohio, Washington state and New York City.

New Hampshire’s directive, which extends until April 7, also will ban public gatherings of 50 people or more.

New Hampshire’s circuit, superior and supreme courts will remain open on a restricted basis through April 6, with nearly all in-person proceedings halted.

Exceptions include bail-related matters and plea agreements; requests for protection orders and hearings in domestic violence and juvenile abuse cases; and emergency proceedings, including those related to the COVID-19 public health emergency.

In-court proceedings are limited to attorneys, parties, security officers and other necessary people as determined by judges.

On Monday, state officials offered guidance to city councils, boards of selectman, zoning boards and other groups trying to figure out how to continue their work while minimizing the spread of the new coronavirus.

Sununu and Attorney General Gordon MacDonald sent a memo to municipal officials and others about the state law requiring such groups to hold their meetings in public. They said in the event of an emergency, a board may meet electronically, but it must still give the public 24 hours notice. Such meetings must also provide public access, which could include providing a call-in number for meetings conducted by phone.