Colorado fights back against anti-vaxxers amid possible whooping cough epidemic

In the wake of recent outbreaks of preventable diseases like measles and whooping cough, Colorado officials are mulling plans that would make it more difficult for parents to acquire vaccination exemptions for their children.

At the moment, all a parent needs to do to exempt their children from otherwise mandatory inoculations is fill out a form documenting a religious or personal/philosophical objection to vaccination.

Colorado is currently one of only 18 states that allows for exemptions based on personal or philosophical grounds, and at the moment, claiming that exemption is as simple as signing a single form affirming that the "[p]arent or guardian of the above named person or the person himself/herself is an adherent to a personal belief opposed to immunizations."

Over 90 percent of parents who acquire vaccination exemptions in Colorado do so for these undefined "personal beliefs."

Officials have been forced to reconsider the ease with which such exemptions can be acquired as a possible whooping cough epidemic spreads across the state. In November 2013, 1,505 cases of whooping cough were confirmed, up from 419 in 2011.

Though Rachel Herlihy, Deputy Director for the Division of Disease Control at the Colorado Department of Health and Environment, claimed that this spike is due to changes in the pertussis vaccine and an ordinary disease cycle, she also told The Denver Post that "children who are unvaccinated are eight times more likely to contract pertussis. Research has shown that outbreaks of preventable disease tend to be more likely to occur in communities with low vaccination rates."

Currently, almost 6 percent of school-age children in the state have not been vaccinated, which is not only dangerous to the unvaccinated children, but threatens the health of many others as well. Large populations of vaccinated people create what is called "herd" or "community immunity," in which vulnerable individuals are protected by virtue of diseases not being able to spread from one person to another because immunized individuals break the chain of infection.

If the proportion of unvaccinated individuals in a given population becomes too high -- that is, if the "herd immunity threshold" is not met -- the potential for an outbreak increases. According to the CDC, the herd immunity threshold for whooping cough is between 92 and 94 percent, meaning that Colorado's almost 6 percent unvaccinated rate is threatening to create the conditions necessary for herd immunity failure, i.e. a full-bore epidemic.

In an editorial in The Denver Post, the executive director of the National Vaccine Information Center -- a clearinghouse for vaccination denialism "dedicated to preventing vaccine injuries and deaths" -- Theresa Wrangham claims that "[t]here is no infectious disease crisis in Colorado that justifies changing the personal-belief vaccine exemption law."

But that could change if Wrangham and other vaccination denialists convince more parents to send their children to school without vaccinating them first.

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