From Taliban fighters to California soccer moms, those who choose not to vaccinate their children against preventable diseases are causing a public health crisis.

Disease outbreaks have killed millions of people, and scientists have spent generations developing ways to save those in jeopardy. Still, many people don’t think it’s a good idea to protect themselves or their children from preventable diseases, and choose to forego vaccinations.

Even in 2013, the anti-vaccination movement continues to leave the door open to outbreaks of diseases that have been all but eradicated by modern medicine. These diseases include measles, polio, whooping cough, and more.

In Pakistan, polio remains an epidemic because the Taliban has banned aid workers from vaccinating children. They say they fear that vaccination efforts are simply a ruse meant to disguise espionage. Health workers attempting to distribute vaccines there have been attacked and killed. A total of 101 polio cases have been reported in the country as of mid-November, and another 240,000 children have not been vaccinated.

But it’s not just militants abroad who are endangering public health by skipping out on vaccinations.

Read What the CDC Has to Say About the Autism-Vaccine Link »

In 1998, British journal The Lancet published research by Dr. Andrew Wakefield that purported to show that the measles, mumps, and rubella (MMR) vaccines caused autism in some children. The study was widely reported and the information spread like wildfire among parents, especially those with autistic children.

One of the loudest broadcasters of this supposed link between vaccines and autism is actress Jenny McCarthy, who has campaigned in support of Wakefield’s findings as recently as 2011.

The problem with Wakefield’s study, however, was that it relied on faulty data. Later investigations have shown that Wakefield was set to benefit from lawsuits based on his research. The study was retracted after numerous other scientists could not replicate his findings.

Since then, no other medical research has shown a link between vaccines and mental disorders. Nevertheless, many parents still hold reservations about vaccinating their children. Wakefield’s paper has been linked to declines in vaccination and a corresponding increase in measles cases.

In March, the U.S. Centers for Disease Control and Prevention (CDC) released a study showing that an aggressive vaccination schedule does not contribute to an increase in autism incidence.

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There are, however, a few real reasons why certain children should avoid vaccinations; specifically, those who are undergoing medical treatment or are still too young.

Earlier this year, researchers confirmed that a 2010 whooping cough outbreak in California, the nation’s worst in over 50 years, was spread by children whose parents applied for non-medical exemptions to school vaccination requirements, many for religious reasons.

The study showed that more cases of whooping cough occurred in the clusters of unvaccinated children than not, resulting in 9,120 instances of the disease and 10 deaths. In San Diego county alone, there were 5,100 exemptions and 980 whooping cough cases.

In August, the Texas megachurch Eagle Mountain International Church made headlines after 21 members of its congregation contracted measles. Coincidently, the outbreak occurred during National Immunization Awareness Month.

The church, part of Kenneth Copeland Ministries, advocated abstaining from vaccinations over fears that they can cause autism. The outbreak was traced back to a church member who had traveled abroad on a mission trip and then spread measles among the unvaccinated congregation.

Following the outbreak, the church hosted vaccination clinics and urged its members to attend.

Also this year, a review of data from the 2009 flu season showed that the use of flu vaccines can help prevent fetal death, a major concern for pregnant mothers. For years, pregnant women have been unsure about whether getting the flu shot could harm their unborn child.

The report, published in the New England Journal of Medicine, also confirmed the safety of flu vaccinations for women in the later stages of pregnancy.

Hopefully, the next generation of parents will opt to protect themselves and their children from diseases we should no longer be worrying about.