Measles are not confined to just unvaccinated individuals. While the measles vaccine is one of the most effective available today, some people who have been vaccinated are still susceptible to the virus. The latest outbreak, with an epicenter at Disneyland Resort, occurred during the holidays where 34 people contracted the disease. 82 percent, or 28 out of the 34 people in California that came down with the measles were not immunized, according to health officials. The six remaining patients were determined to have been previously vaccinated for the disease. It was possible for six immunized individuals to contract the measles virus because the vaccine has an effective rate of about 99 percent for measles virus prevention.
According to the medical director at CalOptima, Dr. Roberto Madrid, the medical insurance program for Orange county’s poor, there are additional factors to take into consideration as well. Effectiveness of the vaccine may decrease over time and some individuals may have gotten just one of two recommended doses, making the vaccine not as effective as it could be. He further stated that he believed the possibility exists that thousands of individuals were in contact with the virus, particularly at Disneyland, but were not affected due to the fact that they were vaccinated.
Although some vaccinations for school-age children are mandatory throughout the nation, certain states, including California allow parents to avoid vaccinations for their children when they sign a waiver. California requires that children who are 4 to 6 years old receive two inoculations of the vaccine MMMR. These injections are for mumps, measles, and rubella.
Adults are being encouraged by health officials to get vaccinated also. People who are not certain if they were vaccinated when they were a child should request their doctor to do a lab test to determine their blood sample antibodies level for the virus. Madrid stated that the tests usually can be done in a doctor’s office, but it may be a few days before the results are available.
The deputy director of the California Department of Health, Dr. Gil Chavez presented a possible scenario as a model as to how measles might spread. In this scenario where 1,000 individuals visited the Disneyland Resort and 950 or 95 percent, of those people, are vaccinated, 1 percent or nine of the immunized individuals are not completely protected from the virus. In this example, 50 of the visitors or five of the remaining percent are not immunized, for a total of 59 possible infections.
The fact that measles is not confined to the unvaccinated is worrying since the Centers for Disease Control and Prevention noted that research studies have revealed that an infected individual has a 90 percent possibility of transmitting measles to a person who is in close proximity and is not immunized. Health officials believe that this latest outbreak at Disney Resorts most likely occurred when an infected park visitor contracted the disease while overseas.
Throughout the state, at least 42 cases of the disease have been traced to the Disney resort outbreak. In recent weeks, Orange County has confirmed at least 20 cases, 12 of which have theme park links. Nine more cases have been traced to Oregon, Colorado, Washington, Arizona, Utah and Disneyland Resort in Mexico.
Saint Jude Medical Center infection prevention director, Claudia Skinner said that because immunity can diminish over time, adults vaccinated as children may receive a benefit from getting another vaccination, known as a booster. People believe that if they were vaccinated as a child that they have lifelong immunity and is not always true, Skinner stated.
Though measles is not just confined to the unvaccinated, health officials believe adults who had measles when they were children, and people born prior to 1957 that have been exposed to measles would have acquired lasting immunity. The vaccine for the measles virus was first utilized in 1963.
By Gerald Sowell
Photo By NIAID – Flickr License