What Parents Should Know About Measles Amid Lancaster County Outbreak
Dr. Pia Fenimore
Dr. Joan Thode
The U.S. Department of Health and Human Services is currently continuing to support measles, mumps and rubella vaccination (the MMR vaccine) for all children, so we were not planning to include measles in our series of vaccination columns. However, because there are cases of measles in Lancaster County, we want to offer information that may empower you in your decision-making about measles vaccination.
As we write, there are six cases of measles identified in Lancaster County. The Pennsylvania Department of Health is leading the intense contact tracing required to help contain the spread of this disease.
Cocalico School District and Lancaster Academy of Performing Arts have been notified about possible exposures. Public health resources are being spent to identify and mitigate risk, and health care providers are fielding a multitude of fears and questions from parents of babies, children fighting cancer and other at-risk populations.
Measles is more than a mild childhood illness — it is highly contagious and can lead to serious complications.
So we are begging parents, school and government officials and health care systems to take action now to reduce the risk of additional measles cases so we do not lose even one child. We know from previous outbreaks as well as history that if there are enough cases, eventually a child will die, and many more infected individuals will suffer from long-term effects of the disease. These risks are no longer hypothetical for Lancaster County, and we do not have the luxury of debate about the facts.
Those facts: Measles is the most contagious virus on Earth; measles can be a dangerous disease in the short and long terms; the MMR vaccine is very safe and effective; and vaccination is the most effective way to protect children from measles.
How is measles different?
Everyone knows the most obvious sign of measles: The telltale red rash. But it’s also accompanied by high fever, cough, a runny nose and red, watery eyes. Symptoms usually emerge seven to 14 days after infection.
With measles, acute infection is only half the story.
Unlike many other viruses and illnesses, measles can leave the body with a legacy that continues way beyond the acute infection and can cause later significant disease and death.
The first of these “legacy gifts” is decreased immune system capacity.
Measles thwarts the potential protection of your immune system after infection by inducing “immune amnesia,” causing the immune cells’ familiarity with all of the viruses and illnesses your body has ever encountered to vanish. This new naivety of your immune system leaves you much more susceptible to future pathogens.
Additionally, anyone who contracts the measles disease is at risk for a degenerative disease of the brain that occurs on average six to 10 years after the acute measles infection (though it can occur up to 24 years later). Called subacute sclerosing panencephalitis, this condition causes the nerve cells in the brain and spinal cord to break down, causing seizures, intellectual regression and an unpreventable death. There is no way to predict which measles-infected individuals will go on to develop this condition, but studies of cases in countries with endemic measles indicate that contracting measles younger than 2 years of age greatly increases the risk, with multiple papers citing a frequency of 1 in every 600 cases. This condition was the cause of death of a school-age child in California last year. That child had originally contracted measles as an infant, when the child was too young to get the MMR vaccine.
As pediatricians, we recognize that information aimed at parents is abundant and often comes from trusted sources such as friends and family. Parents also are bombarded by information from the internet.
Because of our lifelong dedication to caring for children, our Hippocratic oath and our licensing, we are not only driven to — but are mandated to — provide you with the advice that is the best for your child. With that in mind, we encourage families who have delayed measles vaccination to discuss options with their pediatric health care provider.
Beyond that, it is time to address a few questions as we move into this new reality.
How is an outbreak defined?
An outbreak of measles is when there are three or more cases that are linked in some way (same location, household, etc.) and occur during the same defined time. Outbreaks typically occur in one group of people — for example, the current Lancaster County measles outbreak is affecting schoolchildren. After exposure, the possibility for more cases extends for 21 days.
How is contact tracing done?
State Department of Health workers are essentially detectives: They will contact every person who might have breathed the air shared by an infected individual in every specific location they visited during their infectious time frame. This is a daunting task.
Once these individuals have been identified, the Health Department will review their vaccination status and date of birth to identify if they are immune to measles. If they are immune, no further action is required. If the exposed individual has no immunity from prior exposure or vaccination, then the calendar starts on the mandatory home quarantine for the 21-day incubation period.
Why 21 days? Based on blood research, that’s the length of time measles can be in the body, multiplying and taking up residence. The virus particles can be present in exhaled air and body fluids during this period, even if the person is not yet showing symptoms. It’s typically during this presymptomatic period that community measles spread occurs, so this is the critical time to keep infected individuals out of public spaces.
The state Health Department regularly checks in with these individuals and families to monitor symptoms. These individuals may be very sick, so they will receive medical support. The Health Department can also help facilitate communication with local hospitals to mitigate the risk of a patient’s infectious status affecting other patients.
The Health Department and local health care providers will beef up vaccination access, and prep for hospital care of infected patients. The Health Department will also issue guidance on accelerated vaccine schedules for infants at risk.
That state agency wants what we physicians want: the wellness and recovery of all.
How can we help?
If you hear of a case of measles, you’re worried you might have measles or there is a case within your social circle, please notify the Department of Health at 877-PA-HEALTH (877-724-3258). This helps the agency respond as quickly as possible to help protect the wider community. Every exhalation of an infected person spreads viral particles, which are small enough to hang in the air for two hours after the person has left a space. Contacting the Department of Health will not lead to punishment or law enforcement involvement — it gives another foothold to the teams that are trying to efficiently stop the spread.
Might vaccine guidelines change in outbreak?
Potentially, yes. The MMR vaccine can be safely given to babies 6 months of age and older. This vaccine won’t “count” toward the two doses that they will need to get after the age of 1 year, but if measles comes to a baby’s community, it’s worth it to have babies protected as much as possible.
The call whether to proceed with an early vaccination schedule depends on the rapidity of spread and number of cases in the community.
If state Department of Health efforts to contain an outbreak are outflanked by the speed of measles’ spread, then based on many factors and prediction models, this call will be made.
Giving children a second MMR dose before age 4 also might be considered.
At this time, however, we are nowhere near this point, and we hope we will not reach it.
Checking with the Pennsylvania Department of Health website as well as your child’s pediatrician’s office is important. Also, Penn Medicine Lancaster General Health’s infectious disease department is working closely with state health officials to ensure the provision of timely information and adequate vaccination stock.
What have we learned?
The South Carolina Department of Health said that state had 933 confirmed measles cases as of last Tuesday; 235 people were in quarantine and six in isolation.
In early January, that agency recommended an accelerated vaccine schedule starting at 6 months rather than 12 months to protect infants. Thanks to heroic efforts, nearly 1,200 doses of the MMR vaccine were administered to infants aged 6-11 months in January.
Still, measles cases continue to be on the rise. Almost all of the measles cases in South Carolina have been in unvaccinated people.
According to the University of Minnesota’s Center for Infectious Disease Research & Policy Research and Innovation Office, South Carolina’s is now the largest measles outbreak the United States has faced in nearly three decades. It has surpassed the 2025 outbreak in West Texas that resulted in the deaths of two previously healthy school-age children.
What we have learned from these and other outbreaks is this:
A few cases of measles can become hundreds very quickly
Quick action on the part of an organized health department is critical
The financial costs of dealing with an outbreak can be high (a 2018-2019 measles outbreak in New York City cost taxpayers $8.4 million)
Community leader support for isolation, testing and vaccination makes a big difference
Convincing unimmunized people to get vaccinated limits the outbreak quickly
Hospitalization is not uncommon; death is less common with the acute illness but does occur. As we have stated multiple times in this column series, one preventable death is too many
How can we protect the most vulnerable?
This will be a concern for anyone with an infant or immune-compromised child.
If multiple cases of measles are reported in a geographic area and are declared by the state Health Department to be a threat and/or an outbreak in a region, the best way to avoid measles is to avoid public spaces, especially indoor ones.
Schools, stores, malls, sports arenas, theaters and other places where people congregate are all unfortunately risky due to the ability of the measles virus particles to hang in the air and be universally inhaled.
What if a family member is exposed?
If the child or adult has received two doses of the MMR vaccine, they will very likely not contract measles.
If a baby or other individual without measles immunity is exposed to the measles, they have a 90% chance of contracting measles.
The options to prevent or at least decrease the severity of the disease after exposure include giving the MMR vaccine within 72 hours of the exposure (if over 6 months old). Alternatively, immunoglobulin — an injected serum of trained white blood cells that know how to recognize and fight measles — can be given within six days of the exposure (including to babies younger than 6 months).
Lancaster is not just a county, but a community. Within a community, we all belong to one another, and in the context of measles, we all can play a role in preparing for, preventing and protecting against this dangerous virus for our health and that of others.
Pia Fenimore, M.D., is a pediatrician at Lancaster Pediatric Associates and vice chair of pediatrics at Penn Medicine Lancaster General Health. Dr. Joan Thode, M.D., is a pediatrician at Penn Medicine Lancaster General Health Roseville Pediatrics. Both are fellows of the American Academy of Pediatrics.
