The current outbreak of measles in California can be traced back to Disneyland. Photo /Creative Commons
The current outbreak of measles in California can be traced back to Disneyland. Photo Glen Scarborough /Creative Commons

If measles breaks out in any Berkeley school, the Berkeley public health department will direct all unvaccinated children in that school to stay at home for 21 days, the department announced on Jan. 29. This applies to both public and private schools.

The announcement comes as California is experiencing an unprecedented number of measles cases, most linked to a December outbreak at Disneyland. There have been more cases of measles reported in January 2015 than there were in all of 2014, according to Dr. Janet Berreman, Berkeley’s director of public health. Since measles is highly contagious, those numbers are expected to climb.

“I am strongly encouraging families who didn’t vaccinate their children to reconsider that decision in the face of a statewide outbreak of measles,” said Dr. Berreman.

There have been 79 reported cases of measles in California since December, with six of those in Alameda County. Four of those cases have been linked to children exposed at Disneyland. No cases of measles haver been reported in Berkeley.

The reappearance of measles after decades of dormancy worries public health experts. Some have tied the outbreak to the growing popularity of the “anti-vaxxer” movement, where parents decide not to vaccinate their children or stretch out the period between shots longer than doctors recommend.

“The current outbreak can’t be considered momentous in terms of mortality, but it’s still a very large red flag for the U.S. public health system,” John Swartzberg, an emeritus professor at the UC Berkeley School of Public Health told California magazine this week.  “It says there are far too many people in our nation who aren’t protected from disease by immunization. We don’t have that herd immunity that widespread vaccination once provided.”

Herd immunity, also known as community immunity, happens when a significant portion of any group has been vaccinated, reducing the likelihood of contagious disease passing from individual to individual. The higher the proportion of people who are vaccinated, the smaller the likelihood that a susceptible individual will encounter someone contagious.

Health officials have said that herd immunity for measles declines when more than 12% to 18% of any group is not vaccinated. Some experts say herd immunity for measles declines when just 6 to 8% of people are not vaccinated.

In recent years, the rate of vaccinations in California has been dropping, although the state reported a slight uptick in vaccination rates for 2014. About 90.4% of the 535,332 students enrolled in reporting kindergartens had gotten all their vaccinations, a rise of 0.2% from 2013, according to state figures released in December.  The number of children who are not vaccinated declined too, from 3.15% of the Kindergarten population in 2013-2014 to 2.54% in 2014-2015. More students in public schools are completely vaccinated than students in private schools.

Families can apply for a Personal Belief Exemption not to vaccinate their children. Changes in the law now require any family who is not vaccinating their children to meet with a health professional and discuss the situations.

A recent study published in the journal Pediatrics of children in the Kaiser Permanente Northern California system showed that Berkeley was in the center of a swath of under-vaccinated children compared to the population as a whole.

There are at least six elementary schools in Berkeley where fewer than 88% of the Kindergarteners are vaccinated, the threshold some consider for herd immunity to be effective. They include Cragmont Elementary, where 85% of the students are fully vaccinated; Emerson Elementary, where 86.90% of the students are vaccinated; Jefferson Elementary, where 77.50% of the students are vaccinated; Berkeley Rose School, where 13% of the students are vaccinated; Berkwood Hedge, where 70.60% of the students are vaccinated; and Ecole Bilingue, where 77.90% are fully vaccinated.

These are rates reported to the state in October 2014 and supplied by the Los Angeles Times.

State law requires any family who is not vaccinating their children and is asking for a Personal Belief Exemption to meet with a health professional and discuss the situations.

Those percentages may not accurately result the situation now, said Leah Redwood, the administrator for Berkeley Rose, a K-4 school on Rose and Arch streets that uses Waldorf instruction methods. The school, which was founded in 2009, has 75 students. Many of them are in Kindergarten and were too young in October, when the reports were due, to have gotten all of their vaccinations, she said. Some have been vaccinated since then, so the 13% rate may be higher, although the school does not compile statistics, she said.

The reasons people don’t choose to vaccinate their children are varied, said Redwood.

“It is a decision between each family and their health care provider,” she said. “There are lots of reasons why parents decide not to vaccinate. There may be a condition in the family. Maybe there has been a reaction in one of their children. It can be any number of reasons.”

Measles is a highly contagious disease and the incubation period is three weeks. Infected people are contagious for four days before developing the telltale rash.

About “90 percent of those without immunity who share a living space with someone with measles will contract it,” according to the health department. “People contract the virus through airborne particles that can linger in the air for up to two hours.”

Vaccinating against measles is an effective way to ward off the disease as two doses of the MMR (measles-mumps-rubella) vaccine gives immunity to 99% of those vaccinated.

“What we are seeing statewide is more measles cases than we have seen in prior years,” said Dr. Berreman. “So that’s a message to us that measles are circulating in the community more broadly than it has in the past and that increases our concern about making sure everyone is vaccinated.”

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Frances Dinkelspiel, Berkeleyside and CItyside co-founder, is a journalist and author. Her first book, Towers of Gold: How One Jewish Immigrant Named Isaias Hellman Created California, published in November...