What to Know Officials say one of the three newest cases has not yet been linked to other cases, meaning it could be Montgomery County's first incident of "community spread."

One of the cases in Montgomery County is a doctor known to have traveled overseas who was being treated at a Philadelphia hospital in critical condition.

Three newest cases are women, ages 18, 62 and 70. The youngest woman is a student at Germantown Academy. The 70-year-old woman has not yet been linked to other travel-related cases.

Three women are the latest coronavirus cases identified in Montgomery County, Pennsylvania, bringing the total in the suburban Philadelphia county to eight.

One of the women is an 18-year-old student at Germantown Academy, county officials said. She and a 62-year-old woman, who lives with another person previously diagnosed with the virus, have had their links to other cases of COVID-19 identified.

The third case, a 70-year-old woman, has not yet been linked to other cases, officials said.

"The contact tracing for this individual is not fully complete. We are unable to determine how this individual became infected with COVID-19," County Commissioner Chairwoman Dr. Val Arkoosh said Tuesday afternoon. "But I want to emphasize: We have not completed the contact tracing.

Arkoosh added, "Should we be unable to determined how she was infected, this individual would represent Montgomery County's first instance of community spread."

A day earlier, a doctor who works at a King of Prussia health facility was identified as one of Montgomery County's cases.

The doctor was exposed to the virus while out of the country, state and county health officials said Monday.

The Lower Merion School District then announced it would close schools Tuesday after learning that two students, along with a Lower Merion school staff member, may have been exposed to the virus after seeing the doctor.

The doctor's case of COVID-19 brought the total to seven in Montgomery County, next to Philadelphia. The total positive tests for new coronavirus in Pennsylvania rose to 11 by Tuesday morning as the Department of Health announced an eighth case in Montco.

The case revealed Tuesday morning is a person who has been hospitalized.

Several other schools in the Pennsylvania suburbs followed Lower Merion's lead and announced closures as well. Get the list of school closings.

The Cheltenham School District announced it would close for the rest of the week after a parent of a student in one of the township schools came in contact with a coronavirus patient.

CSD has learned of a district parent who cared for a patient with a presumptive case of COVID-19 (coronavirus). The parent and child are self-quarantined. Because of this and any possible transmission to community members, all CSD schools and buildings will be closed 3/10-13. — Cheltenham SD (@CheltenhamSD) March 9, 2020

The Norristown School District will also close on Tuesday after officials confirmed a student and parent in their district had direct contact with the doctor. Neither the student or parent have shown symptoms however, they will remain in isolation and self-quarantine for two weeks as a precaution.

The Upper Merion School District also announced they would close Tuesday to clean their building.

Viking Nation, as a precautionary measure schools will be closed on Tuesday, March 10th in order to allow us to perform “enhanced cleaning” within our buildings. All after school and evening activities will also be cancelled on Tuesday. I appreciate your patience! #vikingnation — Dr. John A. Toleno (@DrToleno) March 9, 2020

Neshaminy High School will close Tuesday after officials determined a student was in contact with the CHOP doctor. The student and two family members quarantined themselves at home as a precaution.

The West Chester Area School District announced Henderson High School in Chester County will be closed for cleaning on Tuesday after officials determined a student was exposed to the doctor's office in King of Prussia. That student is not exhibiting any COVID-19 symptoms but will be held under quarantine with his family for two weeks as a precaution.

The Union-Chadds Ford School District announced Unionville High School and Patton Middle School in Chester County will both be closed on Tuesday for deep cleaning due to a student in the district who visited the CHOP facility in King of Prussia.

County officials said that, despite the contagion connection between the doctor and the various students, all official cases still linked contraction of the virus with travel to other countries.

"This is travel-acquired disease," Montgomery County Commissioner Chairwoman, Dr. Val Arkoosh, said Monday afternoon of the doctor's case. "We have not seen, as yet, community spread."

Sources with knowledge of the situation confirmed that the new case is a Children's Hospital of Philadelphia doctor working at the health care organization's King of Prussia office.

In a letter sent to CHOP staff and obtained by NBC10, hospital president and CEO Madeline Bell said that any staff or patients' families who came in contact with the hospitalized cardiologist were directed to self-quarantine for 14 days and would be tested for COVID-19.

On Monday, CHOP suspended services at its KOP Cardiology and Allergy clinics, sending patients to the main campus instead, according to the letter.

Pennsylvania health officials said the doctor was listed in critical condition Monday while being treated at the Hospital of the University of Pennsylvania in Philadelphia.

Penn Medicine confirmed the patient is being treated at the University City medical center. An isolation room is being used, "which is designed for both optimal medical care of patients with infectious diseases and the protection of staff and other patients," Patrick Norton, Penn Medicine’s vice president for public affairs, said.

Officials also said a student at Simmons Elementary School in Horsham, Pennsylvania, may have been exposed to COVID-19 during a visit to the doctor at CHOP. That student has not tested positive and is not exhibiting symptoms. The school is still closing on Tuesday for a deep cleaning however as a precaution. Officials also said the closure may last longer and will keep students and parents updated.

In addition to the doctor, officials also announced two other new COVID-19 cases in Montgomery County on Monday. The cases are an 18-year-old woman who is isolated at home and a 70-year-old woman who was hospitalized.

Germantown Academy had already been closed through Wednesday due to a student's family being exposed. On Tuesday, we learned a student at the Montgomery County school has tested positive for COVID-19, the private school said in an email to the school community Tuesday.

The student, who has no siblings at the school and doesn’t use to bus to get to school, remains in self-isolation, the letter said.

The Montgomery County cases also include an adult man and adult woman who live in the same home in Lower Merion Township. Officials announced Sunday that the man and woman have mild symptoms that don't require hospitalization and are isolated at home, officials said.

They were both exposed to the virus while traveling out of the country to an area where COVID-19 is present.

Earlier on Sunday, Montgomery County officials urged calm but admitted that the new coronavirus will likely spread, one day after state leaders revealed that two people had tested positive in the county.

The first two people who tested positive for COVID-19 – a man and a woman – live in Worcester Township and Lower Gwynedd Township, respectively, and got infected after traveling to states where the virus is present, Montgomery County Board of Commissioners Chair Dr. Valerie Arkoosh said. Their test results will be sent to the Centers for Disease Control and Prevention for confirmation.

Both patients have displayed only “mild” symptoms, do not require hospitalization and are isolated in their homes, Arkoosh said.

“I want to stress to the public not to be nervous about this," she added.

Arkoosh said most of the people the pair were in contact with have been reached by state health officials and have not shown any symptoms. However, she cautioned that more cases are expected to crop up.

“Coronavirus is very contagious, and we fully expect that we will see additional cases here in Montgomery County,” Arkoosh said.

Properly sanitizing your phone can help protect against illness, including coronavirus.

Out of an abundance of caution, the county board of commissioners will sign a disaster declaration, which will provide “more people more supplies with less red tape” by easing some rules on public spending, Arkoosh said.

The move mirrors similar declarations by the Delaware County Council – which reported its first coronavirus case Friday – and Pennsylvania Gov. Tom Wolf.

In addition to the seven cases reported in Montgomery County and the one case Delaware County, one case was reported in Wayne County and one case reported in Monroe County, bringing the total number to 10 in Pennsylvania.

Though local testing came back positive, all 10 Pennsylvania cases still must be confirmed by the CDC.

Coronavirus concerns have led to a cleaning supply shortage throughout our area. NBC10's Aaron Baskerville has the details.

Symptoms of the coronavirus include fever, cough, muscle pain or fatigue and shortness of breath, according to the CDC. The virus has an incubation period – the time between exposure and the first appearance of symptoms – of about five days.

COVID-19 is spread mainly from person-to-person when droplets from an infected person who coughs or sneezes land on someone else’s nose or mouth or enter their lungs, according to the CDC. It can also be spread when someone touches their own mouth, nose and possibly eyes after coming into contact with a surface that has the virus on it.

To prevent the spread of the virus, the CDC recommends frequently washing hands with soap and water for at least 20 seconds – or using an alcohol-based hand sanitizer with at least 60% alcohol – wiping down dirty surfaces and using the inside of the elbow to cover a cough or sneeze.

Arkoosh asked employers to offer paid sick leave to employees to reduce the likelihood of someone spreading the coronavirus by showing up ill to work.

“Obviously, anyone who needs that paycheck to take care of their family is going to come to work because their family is going to be more important to them. So, please consider a policy of methods that would let your employees to stay home, and do that in a way that allows them to continue to provide economic stability for their families,” she said.