A measles outbreak that started in a patient at Philadelphia's top children's hospital has already sickened up to six patients — with health officials fearing more could become infected.
Three unvaccinated pediatric patients at Children's Hospital of Philadelphia (CHOP), as well as an unvaccinated parent, tested positive for the highly contagious virus after an infected hospitalized child spread the disease to two others in the hospital admitted children.
In addition, after one patient ignored quarantine orders and went to daycare last month, at least two other patients are also being monitored for suspected infections.
Experts say people who contract the disease have not been vaccinated against measles, making the risk to those vaccinated low.
Unvaccinated people are urged to get vaccinated against measles, which is more than 97 percent effective against infections with the virus.
Measles is a highly contagious disease that is fatal in up to 15 percent of people who become infected with it.
Three children and a parent at Children's Hospital of Philadelphia (pictured) have tested positive for measles. It took two days to diagnose the first patient, and by then the virus had spread to two others
“We are seeing cases of measles that have spread to vulnerable individuals, including young children,” said city Health Commissioner Dr. Cheryl Bettigole.
“(This is) because people are refusing the vaccination and also not adhering to quarantine recommendations.”
Measles is one of the most contagious diseases ever recorded, causing infections through tiny airborne droplets or through contact with contaminated surfaces.
Patients experience flu-like symptoms in the early stages before a characteristic rash appears, which normally diagnoses the disease.
The disease is especially dangerous for children under five years old, pregnant women and people with weakened immune systems.
The outbreak emerged when a child with flu-like symptoms, who had recently returned from a country where measles is common, was admitted to CHOP late last month, local reports say.
It took two days for the characteristic rash to appear, which then led to the diagnosis of measles – by which time two patients in adjacent rooms had been infected.
For the 2022-2023 school year, three percent of kindergarten children had a vaccination exemption from one or more mandatory vaccines. This is an increase from 2.6 percent during the 2021-2022 school year and the highest the U.S. has ever recorded
The map above shows vaccine exemption rates by state for the 2022-2023 school year, highlighting the top five states with the highest exemption rates
The additional cases included a child who was too young to be vaccinated and a child whose parents refused to have their child vaccinated.
One of the parents of the unvaccinated child later also tested positive for the virus.
CHOP officials say the patients have been quarantined for at least 21 days until their symptoms resolve, making it “absolutely safe” for people who need to visit the hospital.
Health officials in Philadelphia are monitoring people who may have been exposed after visiting four hospitals in the city: CHOP, St Christopher's Hospital for Children, Nazareth Hospital and Jefferson Health.
They are also calling parents whose children attended Multicultural Education Station childcare in Philadelphia between December 20 and 21.
Measles was once widespread in the United States, but the introduction of vaccines led to the disease being declared eradicated in the US in 2000.
About 1,200 cases of measles are diagnosed in the U.S. each year — often linked to international travel to countries where measles remains endemic.
Two doses of the vaccine against the disease – called the measles, mumps and rubella (MMR) vaccine – are 97 percent effective against infection with the virus.
Patients are offered the first dose between 12 and 15 months of age, while the second is administered at least 28 days later.
Adults can also receive the vaccine and will be offered two doses, spread over at least 28 days.
Dr. Bettigole added: 'Children under 12 months of age and adults with weakened immune systems remain vulnerable to measles but are generally protected due to the wall of immunity created by high levels of vaccination in the community.
'If you have not been vaccinated against measles or if you have not vaccinated your children 12 months or older, contact your healthcare provider immediately to do so.
“If you or your child has been exposed to measles, follow public health guidelines to avoid exposing more children.”
The Centers for Disease Control and Prevention (CDC) has warned of declining vaccination rates, saying more than a quarter of a million unvaccinated preschoolers attended school last year.
Data showed seven percent of children were not up to date with their vaccines, above the target level of five percent or below.
At the same time, the proportion of children 'exempt' from school vaccinations continues to rise – to a record high.
Experts say anti-vaccine sentiment fueled by the Covid pandemic is leading to an increase in the number of people avoiding vaccinations, as well as vaccine fatigue.
There was also an outbreak in central Ohio last February that led to 85 cases, mostly among children who had not been fully vaccinated.
And in October last year, health authorities in Idaho also reported cases of the disease.