Arizona Has Lost Community Immunity in Many Places

In the last 2 weeks AZ public health officials have identified and confirmed cases of measles and mumps.  The mumps cases (2) were found in the SE valley and are under investigation by Maricopa County Public Health folks. Another mumps case has been confirmed in Cochise County.  The measles case was found in Tucson in a 12 month old- and appears to have been acquired after travelling to Asia. That case is being investigated by Pima County public health epidemiologists.

The basic detective work will include looking for susceptible contacts and conducting interventions to control the spread. Kids don’t get the MMR vaccine until their first birthday, so infants are at high risk of getting the disease if they’re exposed… so that group along with unvaccinated contacts (whether for medical or choice reasons) will be among the high priority contacts to identify.  You can see the investigation and control measures for both illnesses in Arizona’s communicable disease rules (Pages 34-39).

Measles is more contagious than mumps- but both are easily spread (direct contact isn’t needed to spread the virus).  Both are vaccine preventable diseases.  For measles (the most contagious disease), 95% of children need to be vaccinated to prevent spread.  

Whether these cases transition to an outbreak or epidemic will depend on where the index cases were prior to diagnosis, who was potentially exposed and the vaccination status of the contacts.  If the index cases were isolated or if they were in communities (or medical facilities) with vaccination rates above 95% it’s unlikely that measles will spread beyond the first case. If they were among communities with lower vaccination levels, there’s a good chance there will be more cases. Another wildcard will be whether there were potential infant contacts in doctors offices or clinics if potential exposures happened there.

Many parts of Arizona have vaccination levels lower than “herd immunity” levels, meaning that in many parts of the state we’ve lost community immunity.  Fortunately, Pima County has among the highest vaccination rates in the state, meaning there’s a better chance of containing the disease.  Had the index case been from one of the many communities in AZ with much lower vaccination rates the risk would be higher. Of course- there are pockets of under vaccinated areas in every county- so many communities are at risk these days.  

Arizona is one of eighteen states that allows parents to opt out of vaccinating their child with a non-medical exemption Click this link to view the full report.  In fact, Maricopa County leads the nation in the highest number of non-medical exemptions.  

There are 30 Legislative Districts in AZ. You can click here to find out what District you live in so you can communicate with your elected officials about the importance of community immunity and ensuring they understand you support public policies that encourage immunizations.

BTW: there are science-based resources available to help parents make informative decisions about vaccines such as the CDC, Children’s Hospital of Philadelphia and TAPI.