Physicians Try Cocooning Against Williamson County Pertussis

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Public Health Feature – February 2010


Tex Med. 2010;106(2):37-40.

By Crystal Conde
Associate Editor

Preventing pertussis is a family affair. That's what many Williamson County public health officials and physicians believe.

Their county – just north of Austin – is in the midst of a full-blown pertussis outbreak that has physicians, public health officials, and other health care professionals fighting its spread and trying to save children's lives with a relatively new tactic called "cocooning."

Because infants aren't vaccinated against pertussis until they're 2 months old and they need multiple doses to be protected, they're more vulnerable to the disease than adults are. Centers for Disease Control and Prevention (CDC) guidelines recommend infants receive the first three doses of diphtheria, tetanus, and pertussis (DTaP) vaccine at ages 2, 4, and 6 months. Children receive the fourth shot between ages 15 and 18 months and a fifth shot when they enter school, at age 4 to 6 years.

David W. Martin, MD, chief medical officer of St. David's Round Rock Medical Center, says infants also are most likely to experience serious, even life-threatening, illness. In fact, according to the Texas Department of State Health Services (DSHS), the two Texans who had died from pertussis as of early December were both babies younger than 3 months.

Dr. Martin acknowledges Williamson County has a big problem with pertussis. December data from the health district estimate the pertussis rate, including probable and confirmed cases, at 185 cases per 100,000 residents. David Bastis, Williamson County and Cities Health District (WCCHD) epidemiologist, expects the final 2009 pertussis rate to be close to 200 per 100,000.

Those figures are higher than the pertussis incidence rate for the entire state, an estimated 9.5 per 100,000 residents as of early December.

The Texas Medical Association Committee on Infectious Diseases collaborated with WCCHD, St. David's Round Rock Medical Center, and health care workers in Williamson County to reduce the number of pertussis cases in the county. They're promoting the tetanus, diphtheria, and pertussis (Tdap) vaccine by using cocooning. The strategy protects tiny, unvaccinated infants by encouraging Tdap immunizations among all adults and children who have close contact with newborns. The immunizations thus wrap the baby and family members in a protective "cocoon" against pertussis.

"The goal of the cocooning project is that everyone who comes in contact with a newborn infant receives a Tdap vaccination. We hope to see decreasing numbers of infants presenting with pertussis as a result of the initiative," Dr. Martin said.

The immunization project, funded by a $12,000 grant from DSHS, includes continuing education programs for physicians and nurses on implementing the cocooning strategy in hospitals. In the fall, St. David's Round Rock Medical Center educated obstetricians, labor and delivery nurses, and ancillary staff in the obstetrics department about the county's pertussis problem and on the cocooning strategy.

Two other hospitals in Texas – Ben Taub General Hospital in Houston and Parkland Memorial Hospital in Dallas – have implemented cocooning. St. David's also sent information on the cocooning project to Williamson County primary care pediatricians.

Education is key to the cocooning project.

C. Mary Healy, MD, director of Vaccinology & Maternal Immunization at Houston's Texas Children's Hospital Center for Vaccine Awareness and Research, conducted a continuing education presentation on the cocooning strategy for St. David's Round Rock Medical Center nurses and physicians in November. She also shared the information with more than 200 WCCHD officials, as well as county and school nurses in the fall.

"The response to the cocooning project has been positive. All health care professionals realize pertussis is a problem in Williamson County and want to act to reduce the incidence of the disease," she said.

Dr. Martin says the project will reach approximately 200 mothers per month who give birth at St. David's Round Rock Medical Center, one of the primary birthing centers in Williamson County.


County's Pertussis Rate Puzzles Experts

It's unknown why Williamson County has a significantly higher rate of pertussis than the rest of Texas, according to W.S. "Chip" Riggins Jr., MD, MPH, executive director and local health authority of WCCHD and former chair of TMA's Council on Public Health. WCCHD data of pertussis cases by city in Williamson County indicate the urban areas have higher case counts. (See "Williamson County Pertussis Cases by Area.")

"It makes sense that the urban areas would have a higher rate of pertussis because they're more densely populated, and pertussis is highly infectious," Dr. Martin said.

Dr. Riggins says it doesn't appear that low immunization rates are necessarily at play in this outbreak. According to Mr. Bastis, county-level data on Tdap vaccination are not available. He says WCCHD added a question on Tdap coverage among adults in the county's 2009 Behavioral Risk Factor Surveillance Survey, which will provide an estimate of coverage in adults once the data are available in April.

DTaP immunization coverage for school-age children, he says, compares to the state at more than 90 percent. According to the DSHS 2007 Retrospective Immunization Survey [PDF], 81 percent of Williamson County children were vaccinated with DTP/DTaP/DT by 2 years of age. The state average was 72 percent.

Dr. Healy adds that many people aren't aware that the immunity from pertussis they receive from childhood vaccinations wanes over a period of five to 10 years, making a Tdap booster necessary.

In June 2005, the CDC's Advisory Committee on Immunization Practices (ACIP) began recommending the routine use of Tdap vaccines in adolescents aged 11 to 18 years in place of tetanus and diphtheria toxoids (Td) vaccines. Later that year, ACIP recommended a single dose of Tdap for adults aged 19 to 64 years.

Last summer, DSHS changed school immunization requirements, mainly affecting students entering kindergarten and grade 7. Among the new requirements, students in grade 7 must have a booster dose of Tdap, but only if it has been five years since their last dose of a tetanus-containing vaccine.

Mr. Bastis says the surge of pertussis may be due to many factors and could involve possible changes in the bacteria, vaccine efficacy, and waning immunity in vaccinated individuals. Mr. Bastis says WCCHD and DSHS are analyzing Williamson County pertussis data, describing the epidemiology of the outbreak, and providing guidance on the implementation of effective control measures.

Edward J. Sherwood, MD, chair of TMA's Committee on Infectious Diseases and interim dean for the Texas A&M Health Science Center College of Medicine and vice president for Clinical Affairs, is a former health authority for Williamson County. He says that to his knowledge, the county doesn't have a large population opposed to immunizing for religious reasons.

"We really wonder in Williamson County if we're that much worse than the rest of Texas, or if we're just looking for it harder. But the case counts are so big in the county that I have to believe it's a real outbreak," he said.

Dr. Healy has experience in cocooning; she began a project like the one in Williamson County at Ben Taub. Since early 2008, the Ben Taub initiative has vaccinated more than 7,500 mothers postpartum – 96 percent of those who believed they hadn't received the Tdap vaccine in the past five to 10 years. Vaccination of family members began at Ben Taub in the summer, but Dr. Healy says data on the percentage of family members immunized aren't available yet.

While Dr. Healy can't pinpoint why pertussis is so rampant in Williamson County, she has identified some common barriers to Tdap vaccination through the Ben Taub project. She says most people aren't aware of the risks pertussis poses to infants.

The disease may cause some babies to have trouble breathing, or it may produce coughing spells so bad that babies have difficulty eating or drinking. Severely ill infants can end up in the hospital, and the disease can cause death. As of November, Williamson County had eight hospital admissions (three confirmed and five probable cases) due to pertussis, but no deaths from the disease. According to CDC, about one in 10 children with pertussis get pneumonia, and about one in 50 experience convulsions.

"At Ben Taub, we've had a low refusal rate for Tdap. In my experience, we've found that once we've provided education to health care providers and family members, they're accepting of this," Dr. Healy said. "Once people find out how serious pertussis can be and how effective the Tdap vaccine is, they're willing to be immunized."

Dr. Martin adds that some family members may forego a Tdap vaccination because of a lack of financial resources. While many private insurance plans and Medicaid cover Tdap, that vaccination often is not a routinely covered service when a woman delivers a baby in a hospital. Physicians and hospitals considering a cocooning initiative to prevent pertussis need to make sure women and their families know where they can get Tdap vaccinations.

TMA created a handout titled "Protect Your Baby From Pertussis," [PDF] which is given to mothers who've given birth at St. David's Round Rock Medical Center and is provided to WCCHD for distribution at local clinics. It includes information on Medicaid vaccine providers and Williamson County clinics that vaccinate the uninsured or underinsured based on a sliding fee scale.

Dr. Healy says handouts are given to mothers and hospital staff members, such as nurses or physicians, who advise mothers to share the information with family members. She says the hope is that informing the mothers facilitates vaccination among family members who will have contact with infants.

Cocooning "Good Common Sense"

According to Dr. Healy, CDC began recommending cocooning as a strategy for immunizing adults against pertussis who have close contact with infants younger than 12 months in 2006. But, she cautions, because the tactic is relatively new and not yet widely used, its effectiveness at reducing pertussis rates among infants hasn't been scientifically studied.

She says, in theory, cocooning should be effective and adds that the eventual public health goal is to study how the strategy impacts morbidity and mortality associated with pertussis in infants.

According to the Global Pertussis Initiative, established in 2001 to assess the global extent of pertussis and to evaluate and prioritize pertussis control strategies, cocooning is "worthy of implementation because even protecting some infants would be considered a success."

"Cocooning makes good common sense from a public health standpoint. It's a new immunization platform for which there's no preexisting infrastructure. It involves delivering immunizations to adults in a different way," Dr. Healy said.

Although she thinks cocooning is catching on, Dr. Healy admits it's not the easiest public health intervention to put in place.

"Cocooning has to be implemented from scratch," she said. "With any new vaccination policy, it takes time. Increasingly, I'm seeing hospitals introduce it, but it will take effort. There's so much education and so many elements to put in place for a cocooning project."

Dr. Riggins says that despite the amount of effort required to launch a cocooning project, it's an efficient way to allocate resources.

"Cocooning is more focused than simply telling everyone to be immunized. We can leverage the interest, efforts, and energy aimed at protecting the most vulnerable in our population to get better acceptance of the Tdap vaccine. Then, over time, while protecting newborns by ensuring that their caregivers and family members get the booster, we'll improve all immunization levels in the community. It's good public health," he said.

Cocooning also gives hospitals, doctors' offices, and other health care facilities an opportunity to make sure health care workers receive Tdap vaccinations, Dr. Sherwood says. Dr. Martin adds that as of early December, nearly all nurses at St. David's Round Rock Medical Center exposed to newborns had received Tdap.

For Dr. Riggins, WCCHD's investment in the cocooning project is part of a long-term strategy. He says pertussis has been endemic, but it has been a cyclical disease with peaks every three to five years.

"Cocooning is part of a larger, systems-based approach we're using to fight pertussis in Williamson County, and it could have an even bigger impact down the road. Partnering for education, immunization, and collaboration among public health, schools, hospitals, and practicing physicians has made our system stronger. This is likely to be a long-term problem, and we can't afford to be shortsighted about it," Dr. Riggins said.

For more information about pertussis, TMA's cocooning project, physician resources, and patient education materials, visit the TMA Web site. The site includes a continuing medical education course on cocooning as a strategy to prevent pertussis worth 1 AMA PRA Category 1 Credit.

Crystal Conde can be reached by telephone at (800) 880-1300, ext. 1385, or (512) 370-1385; by fax at (512) 370-1629; or by-email at Crystal Conde.



Williamson County Pertussis Cases by Area, 2009

Pertussis Count

Source: Williamson County and Cities Health District.
*Number of confirmed and probable pertussis cases as of Nov. 24, 2009.

Note: Area is defined by ZIP codes. Some ZIP codes extend outside Williamson County. The case counts in the table apply only to the parts of ZIP codes within Williamson County. Rural areas include Bartlett, Florence, Granger, Jarrell, Liberty Hill, and Bertram.

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January 27, 2016

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