Low vaccination rates increase risk of measles, pertussis

Measles, a disease that in 2000 was declared eradicated in the United States, has made a frightening, if still limited, comeback.

The reasons are complex, with one of the most common relating to a fraudulent study in Britain that appeared to show a correlation between the measles, mumps and rubella vaccine and the rising incidence of autism in children. Such unfounded doubts about the safety of the MMR vaccine helped to fuel the so-called anti-vaxx movement, people who question the necessity and safety of vaccines in general.

Boulder County has not seen any cases of measles, but because the county has a lower, although improving, school vaccination rate than many places and pockets of very low vaccination rates, it is at greater danger for a measles cluster, as health professionals call an outbreak.

For the 2018-2019 school year, the vaccination rate for the MMR in Boulder Valley schools was 92%, on the low end of what’s called herd immunity, the percentage of the population that needs to be vaccinated to prevent a disease from becoming endemic. The St. Vrain schools average of 89% was below herd immunity.

For public health officials, the U.S. measles outbreaks  are frustrating.

“I just think there’s so much misinformation,” said Teresa Luker, immunization coordinator for Boulder County Public Health. “People don’t want to infringe on parents’ rights, but (their decisions) impact others in the population."

Some private schools and preschools have immunization rates at about 50%, meaning that half of students could be vulnerable to a measles exposure. Measles, which are extremely contagious, also have a relatively high rate of complications, said Kaylan Stimson, epidemiologist for Boulder County Public Health.

About 1 in 10 are at risk for ear infections, some of which can cause permanent hearing loss. Much rarer and much more dangerous at 1 in 1,000 is swelling in the brain, which can cause neurological complications, even death.

The effectiveness rate of the current MMR vaccine is 97%. Those who were born before 1989 should check their vaccination records, because they may have received a vaccine that provides lower immunity at about 93% effectiveness. If a person is exposed to measles, they can get an MMR shot within up to 72 hours to prevent the disease. Those unable to be vaccinated, such as infants, have a six-day window to receive immunoglobulin, Stimson said.

While measles is the largest worry currently, Boulder County’s comparatively low vaccination rates also mean that some children may get pertussis, also known as whooping cough. The disease, which is still endemic in the population, typically peaks in cycles of three to five years, Stimson said.

by Cindy Sutter