The fact that measles cases in the United States have reached a 20-year high is directly caused by people who choose not to vaccinate themselves or their children for “religious, philosophical, or personal reasons,” according to the Centers for Disease Control and Prevention in Atlanta. But one leading infectious disease physician says those reasons are “not medical reasons for not getting vaccinated.”
“Whether they recognize it or not, most people who consciously opt out of vaccines are depending on herd immunity – that enough other people will get vaccinated so as to prevent widespread infection. Yet by opting out they are seriously undermining the very herd immunity they depend on for safety,” says Jorge Parada, MD, medical director of infectious disease at Loyola University Health System in Maywood, IL, in a Loyola press release. “It’s a numbers game, and America is losing ground in the fight against preventable disease."
From January 1 to May 23 of this year, the CDC reported 288 measles cases , the highest year-to-date total since 1994. Measles has caused 43 patients to be hospitalized this year, but no deaths have occurred.
Many people who do not get vaccinated benefit from herd immunity because they are indirectly protected from infectious diseases by people who are vaccinated. According to the CDC, when a critical portion of a community is immunized against a contagious disease, most members of the community are protected against that disease because there is little opportunity for an outbreak. However, the problem occurs when a significant number of people are unvaccinated, which leads to outbreaks, and herd immunity no longer works.
Even those who can’t take certain vaccines—such as infants, pregnant women, or people with lower immunity -- get some protection because the spread of contagious disease is contained. "Herd immunity may be life-saving for people who medically cannot tolerate a vaccine, for these people are the most vulnerable to disease,” says Parada. “[But] it should be frightening to every single American that people deliberately are refusing vaccinations.”
Many of the unvaccinated people who developed measles in the most recent U.S. outbreak had been outside the United States to developing countries such as India and the Phillippines, where vaccination rates are not always high, and measles cases are common. Because of this, the CDC highly recommends vaccination for Americans traveling outside the United States.
People in developing nations generally welcome vaccines because they see first-hand what infectious disease can do.
“I have worked in Africa and Europe where I witnessed outbreaks of vaccine-preventable illness due to a lack of access to immunizations, not due to personal choice,” he says. “I saw moms begging for vaccines for their kids. In America, the collective memory of the horrific outbreaks of preventable diseases has faded."
Many unvaccinated Americans don’t understand the risk of natural infection when refusing vaccinations.
“Deliberately choosing not to get vaccinated while relying upon others getting vaccinated is a dangerous combination,” says Parada. “I only hope those who opt out do not come to discover firsthand the potentially devastating consequences of natural infection."