Reno County in south-central Kansas is reporting more than 70 suspected cases of pertussis (whooping cough) this year, as of July 18. Forty-one of the cases are “confirmed or probable,” according to the Reno County Health Department.1 That number is up from 18 reported as of June 29. The county accounts for 20% of the total pertussis cases in Kansas.2
A local newspaper, The Hutchinson News, quoted Reno County Health Department Director Nick Baldetti as saying, “There’s serious concern for a potential exponential spread through our schools.”2 Baldetti’s department is apparently working with school districts in the area to set up clinics to vaccinate children prior to and during enrollment for the school year in August. “This is truly a widespread outbreak. And it is truly on us, as a community, to ensure we are protecting those in our community that cannot protect themselves,”2 said Baldetti.
According to an Eyewitness News 12 report, Ray Hemman, the public information officer for the city of Hutchinson school district, all of the reported cases of pertussis in that district are of children who had been vaccinated against the disease.3 The childhood pertussis vaccine is called DTaP (Diphtheria, Tetanus, Pertussis).
Hutchinson is the largest city within Reno County and is the county’s seat of government. Other districts within Reno include Buhler, Burrton, Fairfield, Haven and Nickerson and Pretty Prairie.
The Hutchinson News reports that, although “scientists say people are protected from the disease if vaccinated” (an inaccurate statement, given the children infected children in Hutchinson school district), people vaccinated against pertussis can spread the disease to others.4
And this is precisely the point to bear in mind as you read about pertussis outbreaks. The outbreaks are not necessarily occurring because of the lack of so-called “herd immunity”—not enough people being vaccinated. They may well be occurring because of the vaccinated population itself.
Remember last year’s pertussis epidemic in California? There were some 10,000 reported cases of pertussis—the worst outbreak of the disease in the state since the 1940s.5
Throughout the year, there were numerous articles in newspapers and other media sources blaming the unvaccinated community for the outbreak. The headlines provide a sense of the obvious bias. Headlines such as “Anti-Vaccination Beliefs are Contagious Like a Disease” in The Washington Post,6 or California’s Deadly Whooping Cough Epidemic Blamed on Anti-Vaccine Campaign” on RT.7
The bias is troubling on many levels. The articles implied or outright said that the reason there were so many cases of pertussis in California was that vaccination rates for children in the state were low relative to other states in the country, and that they had continually been dropping.
An article in Salon titled “California’s Whooping Cough Outbreak is Officially an Epidemic,” published on June 16, 2014,8 quoted the following from an NPR article, “Vaccine Refusals Fueled California’s Whooping Cough Epidemic”:
They compared the location and number of whooping cough, or pertussis, cases in that outbreak with the personal belief exemptions filed by parents who chose not to vaccinate for reasons other than a child’s health. (Some children with compromised immune systems aren’t able to be vaccinated. … They found that people who lived in areas with high rates of personal belief exemptions were 2 1/2 times more likely to live in a place with lots of pertussis cases. “The exemptions clustered spatially and were associated with clusters of cases,” Jessica Atwell, a graduate student at Johns Hopkins Bloomberg School of Public Health and lead author on the study, told Shots. It was published online in the journal Pediatrics.9
The problem is that in all these articles there is a tendency to confuse correlation with causality. The two are not the same. In other words, the fact that there is a pertussis outbreak in an area of low vaccination rates does not mean that the low vaccination rates were behind the outbreak. There may be a correlation between the two, but that does not prove that the former caused the latter.
Let’s start with an interesting view from Dr. Anne Schuchat, who is the director of the Centers for Disease Control’s (CDC) National Center for Immunization and Respiratory Diseases. In an article titled “CDC: Whooping Cough Heading to a 50-Year High,” published by WebMD Health News on July 19, 2012, Dr. Schuchat is reported to have said that “better diagnosis and reporting of whooping cough may be contributing to the increased numbers, along with the fact that the disease tends to peak and wane in cycles. It does not appear that anti-vaccination sentiment among parents has contributed to either the national rise in cases or the Washington State epidemic.”10
Simple. It turns out that in many cases, people (both children and adults) who get pertussis are up to date with their vaccinations. Note the following excerpt from “Immunized People Getting Whooping Cough” published by KPBS of San Diego State University on June 12, 2014: “Most of the people who got whooping cough in San Diego County so far this year were up to date with their immunizations, according to county data. Of the 621 people who contracted the illness, 85% had all their preventative shots—calling into question the efficacy of the vaccine.”11
In a study reported by Reuters on April 2012 and published in the Clinical Infectious Diseases journal, Dr. David Witt and other researchers looked at 132 patients at the Kaiser Permanente Medical Center in San Rafael, CA who tested positive for whooping cough during March-October 2010. Get this… 81% of the patients were fully up to date on the pertussis vaccine, 11% had received at least one round of the vaccine, and only 8% had never been vaccinated.12
More? In 2012, there was a major outbreak of pertussis in Vermont. As of August 10 of that year, public health officials had determined that 90% of 178 infected children in the state between the ages of six months and 18 years old had received at least one dose of the pertussis vaccine, and that about 80% of them had gotten 5-6 doses.13
It only takes a quick scan of the literature online to notice that there are dozens, perhaps hundreds, of articles regarding outbreaks of pertussis, measles, and other contagious diseases around the United States in which the vast majority of the people infected had been fully vaccinated.
So when it comes to blaming those who choose not to vaccinate (for whatever reason they wish), it doesn’t make any sense. The facts just don’t bear it out.
1 Baldetti N. Pertussis (Whooping Cough) Cases still increasing in Reno County. Reno County Health Department July 24, 2015.
2 Green J. Whooping cough outbreak won’t give up. The Hutchinson News July 25, 2015.
3 70 diagnosed with Whooping Cough in Reno County. Eyewitness News 12 July 27, 2015.
4 Green J. Studies reveal a few surprises about pertussis vaccine. The Hutchinson News July 26, 2015.
5 Haynes D. Whooping cough in California hits 70-year high. UPI Dec. 16, 2015.
6 McKenna M. Anti-vaccination beliefs are contagious like a disease The Washington Post Sept. 22, 2014.
7 California’s deadly whooping cough epidemic blamed on anti-vaccine campaign RT June 17, 2014.
8 Abrams L. California’s whooping cough outbreak is officially an epidemic Salon June 16, 2014.
9 Shute N. Vaccine Refusals Fueled California’s Whooping Cough Epidemic Salon Sept. 30, 2013.
10 Boyles S. CDC: Whooping Cough Heading to a 50-Year High WebMD Health News July 19, 2012.
11 Faryon J. Immunized People Getting Whooping Cough KPBS June 12, 2014.
12 Grens K. Whooping cough vaccine fades in pre-teens: study Reuters Apr. 3, 2012.
13 Stein A. Pertussis Outbreak Has State Encouraging Vaccinations for Adults and Children VTDigger Dec. 20, 2012.