NEW YORK - State laws that make it easy for
parents to opt out of vaccinating their children may be contributing to
outbreaks of whooping cough, researchers reported Tuesday.
In an analysis of US vaccine-exemption laws, investigators found higher rates
of whooping cough in states where parents can refuse to vaccinate their child
due to "personal beliefs."
The disease rate in these states was about 50 percent higher than it was in
states that only allowed exemptions for medical reasons and religious beliefs,
the researchers report in the Journal of the American Medical Association.
The same was true of states with "easy" exemption procedures, according to
the study authors, led by Saad B. Omer of Johns Hopkins University in Baltimore.
This includes states such as California, where parents can take a
personal-belief exemption by simply signing a school immunization form. Other
states, such as Maryland, officially allow only religious exemptions; but again,
parents have only to sign a form, making it likely that many take the exemption
for personal reasons.
The elevated rates of whooping cough in these states point to the "very real
consequences" of relaxing vaccination requirements, Omer said in a statement.
Also known as pertussis, whooping cough is a highly contagious bacterial
infection of the respiratory system that causes fits of severe coughing and
breathing difficulties -- often with a distinctive "whoop" sound on inhalation.
People of any age can become infected, but it's most dangerous, and potentially
fatal, in babies and young children.
Childhood vaccination with the combined diphtheria, tetanus and pertussis
vaccine can prevent whooping cough, but the rate of infection in the US has been
climbing in recent years.
This trend is one reason the current study was undertaken, said Dr. Daniel A.
Salmon, an associate professor of epidemiology at the University of Florida
College of Medicine and the study's senior author.
All US states require children entering school to have proof they've received
standard vaccinations, though all also grant exemptions for medical reasons. In
addition, nearly all states also allow exemptions for religious beliefs, while
19 grant waivers for personal beliefs.
In these latter states, more and more parents have been opting out of
vaccination in recent years, Salmon and his colleagues found. On average, the
rate of non-medical exemptions grew by 6 percent per year between 1991 and 2004.
Concerns about vaccine safety seem to be the main reason parents claim such
exemptions, Salmon told Reuters Health. In an earlier study, he and his
colleagues found that 69 percent of parents who sought exemptions did so because
they feared vaccination did more harm than the diseases it prevents.
In part, such concerns stem from the proposed link between the
measles/mumps/rubella (MMR) vaccine and autism -- a link that a number of
international studies have since refuted.
Salmon and his colleagues argue that states should have "administrative
controls" that make non-medical exemptions more difficult to obtain. This,
Salmon said, could look something like the process of becoming a conscientious
objector to the draft.
Parents would apply for an exemption and have to show a "strongly held
belief" against vaccines, he explained. Then the government would either have to
demonstrate an "overwhelming need" for universal vaccination or grant the
exemption.
