The US state of Wyoming has adopted a vaccine law with a contentious provision that would allow parents to opt out of vaccinating their children, provided they believed their faith had been violated.
A similar measure in Texas caused a national outcry when it was seen as rolling back decades of medical progress.
Critics say it fails to go far enough to protect children from the risks of vaccine injuries.
Those on the other side of the debate insist a healthy and rigorous vaccine programme is one of the best ways to protect children and ensure they are protected from potentially dangerous diseases.
The Government of Wyoming made vaccination a requirement for children going to private and public schools in 2003.
School vaccination programmes have continued to flourish, but a Republican state assembly passed a bill on Tuesday that allows parents to opt out of vaccines if they believe other unvaccinated children are vulnerable to “injury or disease”.
Wyoming joins seven other states that have laws granting an exemption on religious or philosophical grounds, according to the Government Accountability Office.
Speaking at a hearing before the state assembly on Tuesday, Republican Governor Matt Mead said children’s educational and socioeconomic futures were at stake in choosing a path to education.
He asked: “Do I want to be a Republican who signs legislation that weakens vaccination?”
In a joint statement with several other healthcare groups, including the Infectious Diseases Society of America, the American Academy of Pediatrics and the American Academy of Family Physicians, a group of immunologists and public health experts said the vaccine bill would promote a broad gap in immunisation rates.
“It is our belief that children should have access to their highly effective vaccination to the extent possible at no cost to them and to their families and a basic understanding of their potential implications for public health should not be denied by adults who insist that their faith is violated when their children are vaccinated,” the statement said.
Vaccines have been routinely used to protect the public against many diseases for decades. Vaccines are generally safe and very effective.
“Vaccines are the most important public health innovation of this century,” said Stephen Bloch, MD, chief of the Division of Infectious Diseases at Memorial Sloan Kettering Cancer Center.
But the effectiveness of several of these vaccines is being questioned by some parents whose beliefs are contrary to the science on the issue.
First viewed as a possible global threat in the 1940s, the measles outbreak of the 1940s and 1950s swept across most of North America and Europe.
It killed 45,000 people and infected another 3.5 million. The disease is no longer deadly in developed countries, but it remains a risk for infants and people with weak immune systems.
More than 16,000 cases of measles have been reported in the US in the first eight months of this year, the Centers for Disease Control and Prevention (CDC) said.
A recent study in the Lancet Journal said vaccines prevent more than 99% of serious complications of measles, and stated the disease should be a thing of the past.
But citing concerns about declining immunisation rates, the authors of the study, Prof Jonathan Drummond, MD, and colleagues, said “immunisation coverage rates should be treated as grossly inadequate”.
The authors warned many healthcare providers and government agencies treat “fear of vaccination” as a plausible reason for not providing immunisation services and support families who choose to vaccinate their children.
As the first state to allow or allow vaccine exemption, Wyoming must also lead the way when it comes to vaccine design and safety, the Infectious Diseases Society of America said.
“VAERS, a Vattenfall company vaccine in the commercial market now available in the United States, is a promising and well-tested vaccine that was developed with international collaboration,” it said.
“VAERS provides immediate protection from measles and other preventable vaccine-preventable illnesses, and has been used to prevent all documented measles-related deaths in the European Union for the past decade,” the group added.