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California Disease Outbreaks Come Amid New Evidence of Vaccine Safety

Health officials say some of the outbreaks of measles, whooping cough and other diseases that plagued California this year could have been prevented if fewer people rejected vaccinations.

Despite a prevalence of research finding that vaccines are generally safe and proven to lower or eliminate the risk for such diseases, many people choose not to be immunized for non-medical reasons, such as their personal beliefs.

In the U.S., most children attending public school are required to receive immunizations against diphtheria, measles, mumps, pertussis, polio, rubella and tetanus. Requirements vary by state. The process for opting out of vaccination requirements also varies by state.

According to the National Vaccine Information Center, California students in kindergarten through 12th grade are required at certain points to receive vaccinations for:

Diphtheria, tetanus and pertussis — known as DTaP; Hepatitis B; Measles, mumps and rubella; Polio; and Varicella, or chickenpox.

The California Department of Public Health also recommends that students entering college in the state be immunized against meningitis.

Californians can opt out of vaccine requirements fairly easily. Some experts say that process is too easy and rates of vaccine exemptions in the state could be contributing to the outbreaks.

Details of Vaccine-Preventable Outbreaks

There have been dozens of vaccine-preventable outbreaks across the U.S. this year, according to health officials. The outbreaks come amid increasingly high rates of individuals receiving exemptions from vaccines, with non-medical exemptions outweighing those obtained for medical purposes. For instance, the rate of non-medical exemptions for the 2012-2013 school year in California was 2.8% while the state’s rate of medical exemptions was 0.2%.

California has been particularly affected by diseases that might have been prevented by vaccinations, health officials said. CDPH Deputy Director and State Epidemiologist Gil Chavez said “the 2014 increase in measles in California was ignited by individuals who traveled abroad and then fueled by spread to unimmunized individuals in California.” Chavez said that while the measles, mumps and rubella vaccine is “highly effective,” most measles cases in California this year were among residents who were unvaccinated or unaware of their vaccination status.

In addition, the state has experienced a significant outbreak of pertussis — also known as whooping cough — this year. While the disease is cyclical in nature, some observers say the outbreak could have been further fueled by unvaccinated individuals. A study of a similar outbreak of the disease in 2010 found that regions of the state with high rates of non-medical vaccine exemptions were 2.5 times more likely to have high rates of whooping cough.

The Question of Safety

“There are a myriad of reasons individuals choose not to receive a vaccine, or not vaccinate their children,” Chavez said. “The increase in anti-vaccine sentiments appears to be related to the dissemination of concerns, assertions and misrepresentations that have been repeatedly disproven.”

A recent review in the journal Pediatrics of 67 medical studies reiterated previous findings that vaccines are generally safe and the risk of severe side effects is very rare. Specifically, the review did not find any evidence that childhood vaccines cause autism or childhood leukemia, both of which have been cited as worries of parents opting not to have their children immunized. However, despite the low risk of side effects, the review did find some negative reactions to immunizations, including:

A link between the measles-mumps-rubella vaccine and fever-triggered seizures; Flu shots can cause fevers that trigger seizures; and Vaccines for rotavirus, a diarrheal disease in children, can increase the risk of bowel blockage.

In an accompanying editorial, researchers wrote that “the adverse events identified by the authors were rare, and in most cases, would be expected to resolve completely after the acute event. This contrasts starkly with the natural infections that vaccines are designed to prevent, which may reduce the quality of life through permanent morbidities, such as blindness, deafness, developmental delay, epilepsy or paralysis and may also result in death.”

However, some individuals continue to opt out of receiving vaccines for fear of long-term health effects or other problems. Fear of autism is still a frequently mentioned reason for opting out of vaccinations, according to health officials.

Efforts To Increase Vaccination Rates

In nine states, the only requirement to opt out of vaccinations is a parent’s signature. More than 20 states require a health care provider’s signature to obtain an exemption. In 18 states, residents must have exemption forms notarized or signed by a health care provider and paired with a letter of explanation.

Lawmakers in seven states considered bills between 2009 and 2012 that would make it harder for residents to obtain a vaccine exemption.

At the other end of the legislative spectrum, lawmakers in 12 states considered bills between 2009 and 2012 aimed at making it easier to opt-out of vaccinations.

A California law — AB 2109 by Assembly Committee on Health Chair Richard Pan (D-Sacramento) — requires individuals to obtain documentation proving that health care practitioners have informed parents about vaccines and diseases before they can opt out of vaccinating their children. Gov. Jerry Brown (D) signed the legislation two years ago. CDPH has begun distributing information about the new requirement to schools, local health departments and providers. In addition, Chavez said the agency will continue “to develop and test materials to address parents’ concerns about vaccines.”

Public health officials also support other campaigns to encourage vaccinations, such as CDC’s Vaccines for Children program, which provides no-cost vaccinations for children in low-income households, and Text4Baby, which allows new parents and pregnant women to receive text messages in English and Spanish about vaccines. In California, such initiatives include Preteen Vaccine Week, National Infant Immunization Week/Toddler Immunization Month, and influenza vaccine and back-to-school vaccination efforts. CDPH also maintains the California Immunization Registry, which provides electronic exchanges of immunization records in an effort to “eliminate both missed opportunities to immunize and unnecessary duplicate immunizations.”

Immunization Won’t Eradicate All Diseases

Even if vaccination rates increase, some diseases for which vaccines exist might not be completely preventable through immunization, health experts point out.

“Unlike many other vaccine-preventable diseases, such as measles, neither pertussis vaccine nor disease confers lifelong immunity,” making the illness “naturally cyclical with peaks occurring every three to five years,” according to Chavez.

But experts generally agree that immunization should be the first step in efforts to ward of disease outbreaks.

“Anytime there are clusters of persons who aren’t vaccinated against pertussis, pertussis is able to spread more easily,” and the severity of influenza outbreaks “is determined by a variety of factors including … the level of vaccination in the population,” Chavez said.