Sonoma County leads state in whooping cough cases

With an outbreak of the respiratory infection Enterovirus 68 in the Midwest, and the continuing spread of Ebola in West Africa, Sonoma County’s health officials have their own worries: the high incidence of pertussis, or whooping cough, among the school-age population. Building on a surge of 50 additional cases per week in the spring months, the county continues to lead the state in by a wide margin in the rate of pertussis cases this year.

The most recent report from the California Department of Public Health shows almost 7,980 cases in the state, 684 of them in Sonoma County, lading to five hospitalizations but no deaths. While larger counties have had more cases, the incidence rate in Sonoma tops the list, over 137 cases per 100,000 persons. The next highest rates lag far behind, about 93/100,000 in Napa County, followed by 80 in Marin. Overall, the state rate is 20.9 per 100,000.

The geographical focus of the highest rates of pertussis does not escape Dr. Karen Holbrook, the deputy health officer for the county’s Department of Health Services. “That’s how it spreads, person to person, and our populations between counties do intermix.”

As students returned to primary and secondary schools last month, they were faced with stricter requirements for immunizations against communicable diseases. Since 1962, California has required certain vaccinations for children starting kindergartens, including whooping cough. Additionally, now students entering seventh grade are required to have an up-to-date Tdap vaccination (which covers tetanus, diphtheria and pertussis). But a disturbing number of parents are pursuing the “personal belief exemption” (PBE) option for their children, refusing some or all of the inoculations due, in many cases, to fears of vaccines and their perceived side effects.

“I do have concerns about the rate of PBEs and the number of people not getting vaccinations – it poses a risk to the individual and those around them,” said Holbrook. The side effects of refusing vaccination are themselves cause for concern, since the so-called “herd immunity” theory holds that for a population at large to be resistant to wide-spread outbreaks of diseases like pertussis, at least 90 percent and preferably 95 percent or more should be immunized.

“We are close to 90 percent overall, across Sonoma County,” said Dr. Holbrook. “Do I want it to be better? Absolutely. But we also have pockets where it’s not that. West County is an area where the proportion of kindergarteners that are up to date on all vaccines is lower. It’s 67 percent in that area, but it varies by school between 23 percent and 91p percent.”

Petaluma City Schools’ elementary district overall had approximately 15 percent of parents sign PBE for the 2013-14 school year, for a vaccination rate around 85 percent, below the margin needed for herd immunity. While some schools boast 100 percent vaccination compliance, like St. Vincent de Paul Elementary, others have unusually low compliance. Only 35.7 percent of seventh graders at Live Oak Charter have received a Tdap immunization, a school where two-thirds of parents have signed PBE.

Numbers are only slightly better for the kindergarten immunization program, with vaccinations at Live Oak Charter under 44 percent and PBEs at 56 percent. Mary Collins Charter School has the next highest rate of PBEs among kindergarteners, at 25 percent. The figures cited are for the 2013-14 school year, according to the state’s Shotsforschools.org website. Results for the current school year’s immunization rates will not be available until October at the earliest, according to Petaluma public schools nurse Darian Chandler.

But she has reason to hope the numbers will improve this year. “The law changed Jan. 1, which no longer gives a parent the right to walk into school, register their child and sign an immunization waiver so their kid can start school,” she said, referring to AB 2109. “Now they have to go to a medical provider with an appointment, sit down with the provider and go over the (risks of) lack of immunization in the hopes that the provider can convince the parent to start immunization.” That provider then must co-sign the PBE request to validate it.

The Tdap immunization now required for seventh-graders, and recommended for adults, was approved about 10 years ago as a replacement for the once-every-decade TD (Tetanus-diphtheria) shots. “Tdap” refers to tetanus-diphtheria –acelluar pertussis, the “acellular” being a less potent form of immunization, but one with fewer side-effects.

Tdap shots are also recommended for pregnant women during their third trimester with each pregnancy, as well as others who will be around newborns, such as parents and grandparents. This is because, Holbrook emphasizes, infants too young to be fully immunized are at highest risk for severe illness.

“When we had grandchildren,” said Chandler, “everyone in our family all went in and got a pertussis booster, even the great grandfather who was 90 years old.”

The recent PBS Nova program, “Immunization – Calling the Shots” that aired Sept. 10 outlines the current issue and its historical context, not just for pertussis but measles, polio and other vaccine-preventable diseases as well. Chandler herself affirmed that of the people she has worked with in medicine, “We all strongly support immunization because we’ve seen what happens. We’ve seen the infant that died of pertussis, and I’ve seen polio in the 50s and 60s.” She recalled caring for polio patients in iron lungs, and pointed out that polio has been all but wiped out in the U.S. thanks to immunization.

Now, she says, “It shocks me when people do not immunize their children against polio.” And it’s not just polio: “In family practice pediatric care there are people that come in, they want the waiver signed, and there’s no way to convince them that the immunizations are safe, much safer than they used to be. The risk of getting the disease outweighs any statistical risk of complications.”

The new requirement that parents consult with physicians about the risks of immunization should help increase immunization rates – at least that’s the purpose of AB 1209. But a law on its own cannot change people’s behavior. Holbrook intends to focus on making this dialog productive in the near future by convening a task force to develop best practices for clinicians to work with vaccine-hesitant parents.

“I don’t want to vilify people choosing to exempt, I want to work with them,” said Holbrook. “I want them to work with their providers to address their concerns and their fears. If it becomes an antagonistic relationship, then the listening shuts down.”