A measles outbreak in Philadelphia has expanded to eight confirmed and three suspected cases, city health officials said Monday. Thus far, three patients have been hospitalized. Vaccine preventable diseases such as measles and polio remain a public health threat. And with childhood vaccine hesitancy on the rise, the problem could get worse.
Officials at the Philadelphia Department of Public Health are now warning the public about several known exposure sites across the city, including several healthcare facilities in the city and a daycare center.
Placed in a larger context, the current situation in Philadelphia speaks to a wider problem of the return of vaccine preventable diseases as a result of the steady increase in vaccine hesitancy in recent years.
Measles was declared eliminated from the U.S. in 2000, which meant that at that time there was an absence of disease transmission for greater than 12 months. But that declaration turned out to be premature. While annual numbers of cases of measles in the 2000s were relatively small, they climbed to 1,274 in 2019, which were confirmed in 31 states. This was by far the greatest number of cases reported in the U.S. since 1992. Notably, all cases in 2019 were linked to travel to countries with endemic measles. Upon returning to the U.S. those infected exposed at-risk populations (un- or under vaccinated) which in turn led to a large number of local epidemics.
In an outbreak in Ohio in 2022, 85 people contracted measles and 36 children were hospitalized. Of the 85 infected, 80 were unvaccinated, 24 of whom were too young to be vaccinated as they under the age of one and hadn’t yet begun their measles, mumps and rubella series of shots. Nevertheless, according to the health commissioner for Columbus Public Health—the jurisdiction where about 95% of the cases occurred—vaccine hesitancy drove the upsurge.
And what this implies is that vaccine preventable diseases remain a public health threat. This includes diseases such as polio, mumps, diphtheria, tetanus, whooping cough and hepatitis B. Data from the Centers for Disease Control and Prevention indicate that measles, mumps and rubella vaccination rates have fallen from 95% to 95% nationwide among kindergarteners since the outset of the Covid-19 pandemic. Furthermore, childhood vaccine exemptions, both medical (due to contraindications) and non-medical, are now at an all-time high. And while still only about 3% of children have non-medical exemptions on religious or philosophical grounds the number is growing and in 10 states is greater than 5%.
The problem of vaccine hesitancy isn’t limited to the U.S. A rise in incomplete vaccine coverage across the world’s population creates fertile ground for a measles rebound.
Based on estimates published in the journal Lancet, the global number of measles deaths in 2020 was 60,700, a 94% decrease from 1,072,800 deaths in 2000. It’s estimated by the CDC that worldwide during a period of roughly two decades beginning in 2000, measles inoculations prevented 57 million deaths.
However, from 2020 to 2022 measles fatalities more than doubled, reaching 136,000.
The most recent spike is attributed to a significant decrease in vaccinations globally during the Covid-19 pandemic as immunization levels dropped to their lowest in 15 years.
This is worrisome. Some of it has to do with the pandemic itself, as routine healthcare services were halted. However, it appears that the decrease owes in part to a burgeoning anti-vaccination movement, triggered or simply reinforced by Covid-19 vaccine mandates, to which many people were opposed.
The more people forego childhood immunizations, the greater the chances diseases such as measles and polio stage a comeback. For measles in particular such a resurgence is facilitated by the fact that the virus is incredibly infectious, with a reproduction number of 16. This means that in a susceptible population, on average a person with measles infects 16 others.
The disease causes an initial flu-like illness with symptoms that include a high fever of over 103 Fahrenheit (39.4 Celsius), copious congestion, red eyes and a rash that spreads around the entire body. Patients with measles can develop ear infections, severe gastrointestinal upset, pneumonia and brain swelling.
According to two studies published in 2019 in the journals Science and Science Immunology, measles can inflict more harm than just the acute infection. The virus can eliminate acquired immune memory by destroying the memory B, plasma and T cells, which in turn cause people to become much more susceptible to infections.
Before the advent of vaccines, in the U.S. an estimated 400 to 500 people died from measles annually while 48,000 were hospitalized and 1,000 suffered encephalitis (swelling of the brain).
The CDC states that about one in five people in the U.S. who contract measles will be hospitalized. And one out of every 1,000 people with measles will develop encephalitis, which could lead to lasting brain damage. Finally, between one and three out of 1,000 people with measles will die.
High-risk groups for serious illness include young children, the elderly, pregnant women and people with weakened immune systems.
There is no known treatment for measles besides supportive care. Once infected, it is vital that individuals quarantine.
Medical experts are reminding the public that the disease can be prevented by being immunized. Specifically, the CDC recommends childhood vaccination with the measles, mumps and rubella vaccine, first at 12 to 15 months of age and then at four to six years of age.
