Whooping cough outbreaks tied to parents shunning vaccines

September 30, 2013 by Serena Gordon, Healthday Reporter
Whooping cough outbreaks tied to parents shunning vaccines
Study finds that areas with high rates of nonmedical vaccine exemptions also had high number of cases.

(HealthDay)—New research confirms what experts have suspected: The decision not to vaccinate children for nonmedical reasons can have far-reaching effects, including raising the risk of infections for other children and their families.

Researchers compared areas with significant numbers of parents who chose not to vaccinate their children for nonmedical reasons to areas that were affected by the 2010 whooping cough outbreak in California. They found that people living in areas with high nonmedical vaccine exemption rates were 2.5 times more likely to also be located in an area with high levels of whooping cough.

"Not vaccinating your child is not a benign decision. It has real health consequences to the individual child and to the community," explained study senior author Saad Omer, an associate professor of global health, epidemiology and pediatrics at Emory University in Atlanta.

Results of the study were published online Sept. 30 and will appear in the October print edition of the journal Pediatrics.

Whooping cough, also known as pertussis, is a highly contagious bacterial disease that attacks the respiratory system. Last year, the United States had the highest number of whooping cough cases since 1955, according to the U.S. Centers for Disease Control and Prevention. During 2012, the CDC received reports of 48,000 cases and 18 deaths, with most of the deaths occurring in infants.

Part of the reason there's been a resurgence in whooping cough is that the newer vaccine, which causes far fewer side effects than the old vaccine, doesn't work for as long as the older vaccine did, the researchers explained. Because of this, it's crucial that children receive vaccines and booster doses on schedule. If there's a delay in vaccination, the risk of whooping cough goes up.

In 2010, 9,120 cases of whooping cough, with 10 deaths, were reported in California. That was the highest number of whooping cough cases in that state since 1947, according to background information in the study. Factors that may have played a role in this outbreak include the waning immunity associated with the newer vaccine, better diagnosis techniques and the cyclical nature of whooping cough.

But, the researchers also wanted to see if the clustering of people who had nonmedical exemptions for vaccines played a role in the outbreak. Omer said that previous research has shown that there do tend to be clusters of people with nonmedical vaccine exemptions.

In California, the rate of such exemptions has risen from 0.77 percent in 2000 to 2.33 percent in 2010, according to the study. Still, the state has relatively high vaccination rates. Almost 91 percent of children entering kindergarten in 2010 had received all the required immunizations, the study authors pointed out.

Omer and his team reviewed data on vaccine exemptions from school data, and they geographically coded that information to the census tract level. They then did the same thing with data on whooping cough cases.

The investigators found 39 clusters for high nonmedical exemption rates and two statistically significant clusters of whooping cough cases. Census tracts within a high nonmedical exemption cluster were 2.5 times more likely to be in a whooping cough cluster than areas without high exemption rates.

The risk of whooping cough was 20 percent higher inside a vaccine exemption cluster than outside of one, according to the study.

In California, clusters and nonmedical exemption clusters were associated with a lower population density, lower average family size, fewer minorities, higher percentage of high school graduates, higher average household incomes and a lower percentage of families living in poverty, the study found.

"There was some nice analysis from the CDC years ago that people who refuse vaccines tend to be higher in socioeconomic status," added Omer.

An expert not involved with the study agreed with that analysis.
"The irony is that normally people with lower socioeconomic status have an increased risk of infectious diseases, but with vaccine-preventable infectious diseases, the risk is higher for those higher in socioeconomic status," noted Dr. Kenneth Bromberg, director of The Vaccine Research Center and chairman of pediatrics at The Brooklyn Hospital Center in New York City.

Some who seek these exemptions argue that it's a personal decision that only they can make for their family. But, Omer and Bromberg both expressed concern because the decision not to vaccinate is likely putting others at risk for infection.

"We live in a free society, but infectious diseases are different from other phenomenon. Someone else's behavior can affect my child or loved one, or me," noted Omer.

"If a parent gets their child vaccinated and that particular vaccine has an 80 percent efficacy rate, that means that even if you don't account for waning protection after vaccination, there's still a one-in-five chance that child can be at risk of being infected. But, the odds are lower if everyone in the community is vaccinated," Omer explained.

"It's personal freedom versus public health," Bromberg said. "We can't always do everything we want in a society. And the issue is more complicated than what was addressed in this article. There are immune-compromised people, and people who receive their vaccines as recommended. By not getting vaccinated, they're putting immune-compromised people at an even greater risk and putting normally healthy people at risk, too," said Bromberg.

Explore further: Whooping cough cases rise as parents opt out of vaccine

More information: Learn more about whooping cough from the U.S. Centers for Disease Control and Prevention.

Abstract
Full Text

Related Stories

Whooping cough cases rise as parents opt out of vaccine

June 3, 2013
(HealthDay)—Parents who opt out of vaccinating their children are putting their own kids and others around them at risk of serious illness, finds a study conducted in New York.

More evidence whooping cough protection wanes

March 11, 2013
(HealthDay)—Despite high levels of vaccination, the rate of whooping cough in the United States is at its highest level in decades, and one reason may be that immunity from the vaccine diminishes each year after the fifth ...

2012 was worst year for whooping cough since 1955

January 4, 2013
Health officials say 2012 was the nation's worst year for whooping cough in nearly six decades.

Undervaccination appears associated with increased risk of whooping cough

September 9, 2013
Undervaccination with the diptheria, tetanus toxoids and acelluar pertussis (DTaP) vaccine appears to be associated with an increased risk of pertussis (whooping cough) in children 3 to 36 months of age, according to a study ...

New whooping cough strain in US raises questions

February 6, 2013
Researchers have discovered the first U.S. cases of whooping cough caused by a germ that may be resistant to the vaccine.

Panel: All adults should get whooping cough shots

February 22, 2012
A federal advisory panel wants all U.S. adults to get vaccinated against whooping cough.

Recommended for you

App helps hearing-impaired parents know when and why their baby is crying

May 23, 2018
For parents Delbert and Sanaz Whetter a crying baby is a particularly difficult challenge. The Whetters are deaf, so when they're in another room they rely on cameras and remote noise-monitors to help keep an eye on their ...

Pregnancy drug DES might have triggered ADHD in the grandchildren of women who used it

May 21, 2018
A study conducted by researchers at Columbia University's Mailman School of Public Health and Harvard T.H. Chan School of Public Health reported elevated odds for attention deficit hyperactivity disorder (ADHD) in the grandchildren ...

Age-related racial disparity in suicide rates among US youth

May 21, 2018
New research suggests the suicide rate is roughly two times higher for black children ages 5-12 compared with white children of the same age group. The study, funded by the National Institute of Mental Health (NIMH), appears ...

One in 10 parents say their child has gotten sick from spoiled or contaminated food

May 21, 2018
No parent wants to come home from a picnic or restaurant with a little one whose stomachache turns into much worse.

Infant growth patterns affected by type of protein consumed

May 14, 2018
A new study by CU School of Medicine researchers has determined that choices of protein intake from solid foods has a significant impact on infant growth during the first year of life.

Parents say intense gun violence in PG-13 movies appropriate for teens 15 and older

May 14, 2018
Parents are more willing to let their children see PG-13 movies with intense gun violence when the violence appears to be "justified," used in defense of a loved one or for self-protection, than when it has no socially redeeming ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Tangent2
1 / 5 (3) Sep 30, 2013
2.5 times more likely to be infected than if you are not vaccinated? Not much better than a 50% chance of being infected or not, which is not an effective vaccine by any measure.

I would rather take my chances with mother nature instead of a concoction based on humans being ignorant enough to think they can out do mother nature.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.