Dozens of cases of an ancient disease once eliminated in the U.S. are suddenly appearing.

The outbreak started in Disneyland in California in December 2014 and spread to many other states.

Measles, first described in the ninth century, was once a rite of passage in childhood.

By the 1950s, most children got measles by their mid-teens, with 3-4 million people infected in a year. Measles left many lives devastated. An estimated 400 to 500 people died per year, mostly children. 48,000 were hospitalized and 4,000 suffered complications of encephalitis with residual deafness or intellectual deficits.

The country was relieved when a vaccine was developed in the 1960s. The highly successful vaccination program that followed meant cases of the disease dramatically declined. By the year 2000, the disease was eliminated in America; a public health triumph.

So Why the Outbreak Now?

Twenty seven states reported 644 cases last year. So far this year, 178 cases have been reported. What happened? In certain areas of the country, we have lost our herd immunity.

What is herd immunity? It means that a group of people (the “herd”) can avoid exposure to an infectious disease because sufficient numbers of people in their environment are immune to that disease. They may have been vaccinated or have immunity from a prior infection. Because they are immune, they cannot catch or transmit the disease.

Herd immunity protects people who cannot be vaccinated because they are too young or too sick. When enough people are immune, those who are not immune don’t come in contact with the disease. Without herd immunity, people not immune to measles are imperiled.

How Did We Lose our Herd Immunity?

A study published March 16 in JAMA Pediatrics revealed pockets of low vaccination rates in the country corresponding to areas with an outbreak of measles. A vaccination rate above 96% is generally necessary for herd immunity. The study estimated vaccination rates in areas with an outbreak were as low as 50% and no higher than 86%.

Why Don’t We Protect Our Children?

Misconceptions and myths about vaccinations persist despite solid evidence. Well-intentioned parents have forgone vaccinations due to misplaced fears. Serious side effects from vaccines are exceedingly rare.

Possible side effects do not include autism — that was a myth created by a now discredited 1998 study. On the other hand, serious complications from measles are not rare and for those not immune, they should be a very realistic fear.

What Can We Do to Stop This Outbreak?

Protect your children and those vulnerable among us who cannot be vaccinated by following the vaccine protocol recommended by your family doctor or pediatrician.

Be informed — get more information, as well as answers to your questions and concerns, from the Centers for Disease Control (CDC).

Vaccines are the most effective and cost-effective tools we have against many dangerous diseases.

Check out these CDC vaccine recommendations for adults and for children.

When Do Adults Need Vaccines?

Some adults incorrectly assume that the vaccines they received as children will protect them for the rest of their lives. Generally this is true. However:

  • Some adults were never vaccinated as children.
  • Newer vaccines were not available when some adults were children.
  • Immunity can begin to fade over time.
  • As we age, we become more susceptible to serious disease caused by common infections (such as flu and pneumonia).

Protect your health and the health of those around you by staying informed and getting the vaccinations you need. Ask your medical provider for guidance if you have questions or concerns. Stopping the spread of measles now can eliminate the potential for a global pandemic later.