In the wake of health officials announcing three more positive cases of coronavirus in Delaware on Thursday, Gov. John Carney declared a state of emergency that will take effect Friday morning.

It requires the Delaware National Guard to assist with the state's response to the coronavirus and recommends event organizers cancel any nonessential gatherings of more than 100 people. The declaration allows the state to conduct public meetings electronically, and it prohibits price gouging during the coronavirus outbreak.

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Carney's announcement at 3:30 p.m. capped a day of schools, health-related institutions and even the state Legislature revealing big changes to cope with COVID-19.

Many colleges are going on spring break immediately and will turn to online classes at the end of the breaks, while K-12 schools are reevaluating their responses. Visitors are being screened and in some cases refused at health-related institutions.

Events planned for this weekend throughout the state, including Wilmington's St. Patrick's Day Parade, were canceled. The Grand Opera House postponed all performances until further notice, and the Wilmington City Council says it will livestream meetings and not allow an audience.

The state Legislature will not go into session next week, as expected. The Court of Common Pleas has rescheduled all criminal court proceedings until June. The state high school athletic association canceled the state basketball tournaments. There will be no NCAA March Madness tournaments or spring championships either.

By limiting events and other gatherings, officials are trying to avoid a rapid spike of cases that could overwhelm the health care system. Experts are encouraging quarantines, even involving people who are less vulnerable, as a means to limit the spread of the virus to vulnerable populations.

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All three new Delaware cases announced Thursday are people under 30 years old who are associated with the University of Delaware, officials said. Two are graduate students, and one is a postdoctoral researcher.

A UD faculty member on Wednesday became the first Delawarean to test positive for coronavirus. Officials said all four were exposed to the same confirmed case of COVID-19 at an off-campus event in another state. All are quarantined.

The cases are described as presumptive positive until confirmed by the Centers for Disease Control and Prevention. In Delaware, state health officials are monitoring 35 people. A total of 44 people have been tested for COVID-19 — 30 tests returned negative results and 10 people are awaiting results.

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UD already had suspended in-person classes Wednesday afternoon after officials announced the first positive case. Classes will shift online when students return from spring break on March 23 until further notice.

Students have the option of remaining in residence halls, and campus dining services are still operating. But on Thursday, the campus was a madhouse, with students packing up to leave and parents and others arriving to pick students up.

The university suspended all spring sports Thursday afternoon.

In a press release, UD said campus spaces that may have been impacted are being disinfected, and it is helping the Division of Public Health track who might have been exposed.

Those who did come in close contact may return home during UD's spring break, public health officials said, but may not use public transportation to get home. They will need to remain home for at least 14 days after their last contact with someone who tested positive.

State health officials have said the man who tested positive Wednesday came in contact with fewer than 50 people because he self-quarantined "quite quickly."

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Delaware State University and Goldey-Beacom College took similar precautions to UD after positive cases were announced. DSU students are not to return to campus until April 5. Courses will resume online beginning March 18 and will continue online until at least April 3.

Goldey-Beacom will switch to online instruction on Monday. Campus will remain open, but large gatherings are canceled. Commencement, which was scheduled for May 1, is postponed. No new date has been scheduled.

The health department recommended that Delaware nursing homes, long-term care facilities and adult day-care centers temporarily end visitation, in order to reduce health risks to residents and clients.

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Taking care of yourself

Health officials encourage residents to follow good hygiene — washing their hands regularly, avoiding touching their faces and sneezing into their elbows. They also recommended stocking up on supplies such as food, water and medicines; avoiding crowds; and having a plan in place in case residents or someone in their family gets sick.

If you are sick, do not go to work, officials have stressed.

Seniors and people with underlying medical conditions should avoid large crowds to reduce their risk of contracting coronavirus.

For those who have concerns or questions about the virus, call (866) 408-1899 or email questions to DPHCall@delaware.gov. UD also has a COVID-19 call center that can be reached at (302) 831-1188, and questions can be emailed to coronavirus@udel.edu.

Natalia Alamdari and Meredith Newman contributed.

Contact Brandon Holveck at bholveck@delawareonline.com or at (302) 324-2267. Follow on Twitter @holveck_brandon.