On September 22, 2006, Stephanie Paredes knew that she was very, very sick.
"I woke up one day feeling so sick, everything was sore, and I felt sick for a whole week," Paredes said. "Then I woke up one day with a really high fever — so high that I was shivering and couldn't stop."
An 18-year-old, first-year student at the University of Virginia, she had no idea what kind of disease she possibly could have caught. But she took her parents' advice to stay home and rest until it passed. Finally, after a week of debilitating illness, Paredes woke up one morning feeling suddenly and inexplicably better.
That is, until she reached up to touch her face.
"My face felt huge," she recalled. "I had a panic attack and ran to the bathroom. When I saw my swollen face in the mirror, I screamed."
Oddly enough, Paredes was exhibiting symptoms of an illness most commonly associated with childhood: the mumps. And while she was one of the first students diagnosed with mumps on her campus, she wasn't the last. Paredes later learned that about 50 more students and teachers at the school also contracted the mumps after she had.
But she did not contract and spread the disease due to her failure to receive proper immunizations. Indeed, like many of the other students on her campus who contracted the disease, she received the two-dose measles, mumps and rubella (MMR) vaccine when she was a child.
Now, new research suggests that the mumps outbreak that began early in 2006 — the largest outbreak of mumps in the United States in two decades — was probably due more to vaccine failure than the failure of people to get their recommended immunizations.
Researchers at the Centers for Disease Control and Prevention looked at mumps cases in the United States in 2006. They studied the 6,584 reported cases of mumps and found that in most cases, the vaccine from childhood no longer provided enough protection in adulthood.
In light of the findings, doctors say a more effective childhood vaccine — or additional booster shots — may be needed to wipe out mumps in the United States.
Still, the researchers noted that the vaccine is not useless; on the contrary, it probably helped prevent a much larger, more dangerous outbreak.
"Two doses of mumps vaccine are very effective and high coverage rates with two doses of the mumps vaccine in the U.S. prevented a much larger outbreak from occurring," said Dr. Jane Seward, lead study investigator and deputy director of the CDC's Division of Viral Diseases. "The U.K., by comparison, had fifty times higher incidence with their outbreak [of mumps] because of less vaccination coverage."
Anatomy of an Outbreak
Mumps is a viral infection spread from person to person, most commonly through sneezing or coughing. The infection usually begins with swelling and tenderness of one or more of the salivary glands, which lasts about a week. Complications can include inflamed testicles or ovaries, as well as inflammation of the lining of the brain and the pancreas.
Like most viral illnesses, the treatment for mumps primarily involves bed rest and over-the-counter pain and fever medications until the illness has run its course.
Before widespread vaccination, there were about 200,000 cases of mumps and 20 to 30 deaths reported each year in the United States. But these numbers were cut drastically by immunization efforts.
Thus, by all measures, the 2006 mumps outbreak in the United States was an aberration. While the CDC reports that the average number of mumps cases nationwide from 2001 to 2005 was 265 per year, there were 3,200 confirmed cases in 2006 across 12 states, primarily in the Midwest.
Some infectious disease experts noted that the 2006 measles outbreak might have been due to the relatively low number of college students who complied with CDC's recommendation in 1989 that everyone receive a second "booster shot" for measles, mumps and rubella.
"I think the degree of two-shot uptake is very important in preventing large outbreaks," said Dr. James Turner, executive director of the Department of Student Health and professor of Internal Medicine at the University of Virginia. "In [this] study… two shot uptake was only 84 percent. I think there is a higher threshold that must be reached before the vaccine prevents widespread disease."
Dr. William Schaffner, professor and chair of the Department of Preventive Medicine at Vanderbilt University School of Medicine, said the only real preventive measure in preventing future outbreaks is to require all U.S. citizens to get a second dose of the vaccine.
"All developed countries should provide all their children with two doses of mumps vaccine," Schaffner said. "Had this been routine practice in England, there would not have been a mumps outbreak there, there would not have been an importation [of mumps into] the U.S. and there would not have been an outbreak here."
But while some experts said the CDC should be more vigilant in its recommendations that everyone receive a second booster shot, others maintain that the most important measure to ensure fewer outbreaks of the disease is public health education.
"No vaccine can protect 100 percent of people 100 percent of the time," said Dr. Mark Slifka, associate scientist at the Vaccine and Gene Therapy Institute at Oregon Health and Science University. "Increased surveillance at college campuses and increased awareness of the hazards associated with [the disease] through increased education efforts … will also reduce the incidence of outbreaks [and] improve response time in controlling outbreaks."
The CDC's Seward added that although the one-dose mumps vaccine is about 80 percent effective at preventing contraction of the disease, and the two-dose vaccine is about 90 percent effective, there are additional factors that put young adults between the ages of 18 and 24 at higher risk.
"We think close-contact living conditions like on college campuses and also decreased vaccine immunity over time contributed to the  outbreak," Seward said.
MMR Vaccine: Truly a Failure?
Although the study, published in the New England Journal of Medicine, points out that the cause of the outbreak didn't have to do with the vaccine failure, many experts cautioned against citing the study as an example of the vaccine's failure without also highlighting its successes.
"While technically the study reports 'vaccine failures,' it, in fact, reports vaccine successes," said Dr. Martin Myers, executive director of the National Network for Immunization Information. "Most of those who had received two doses of vaccine did not develop mumps after exposure, mumps did not spread to the primary or secondary schools, and the outbreak did not expand into an epidemic of the proportion that occurred in Great Britain, [which experienced] 60,000 cases."
Additionally, experts pointed out that those who contracted mumps despite having received their childhood immunizations did not exhibit the more severe symptoms of the disease, such as inflammation of tissues in the central nervous system or inflammation of the ovaries or the testicles.
"So I would assert that the vaccine, though not totally preventing disease," Virginia's Turner said, "seems to prevent complications."