Pertussis epidemic in California linked to vaccination gaps

With California on pace to have its worst pertussis outbreak in 50 years, local and national health officials are working to determine what sparked the resurgence of the vaccine-preventable disease and how transmission can be slowed.

Experts said that no single factor could be blamed for the increase in cases, which was first detected in March. But two possibilities are that some parents don't vaccinate their children due to safety concerns, and some doctors don't offer all the recommended immunizations because of payment issues.

The California Dept. of Public Health says the state is facing more than just a resurgence of pertussis -- it's an epidemic. Between Jan. 1 and July 16, there were 1,496 reported cases of pertussis, state epidemiologist Gilberto Chavez, MD, MPH, said at a July 19 press briefing. Approximately 700 possible cases are under investigation. Six infants have died from the bacterial respiratory disease.

During all of 2009, there were only 965 reported cases and three deaths.

"Pertussis is very contagious and ... it's very much vaccine-preventable. ... It is very important that providers think of pertussis when they have patients who show up with symptoms," said Dr. Chavez, who is also chief of the department's Center for Infectious Diseases.

Michigan and South Carolina also have reported a rise in pertussis cases, but neither state has a situation as serious as that in California, said Thomas Clark, MD, MPH, a medical epidemiologist for the Centers for Disease Control and Prevention.

The California Dept. of Public Health issued new pertussis immunization recommendations on July 19 to help curb the outbreak and bolster the state's vaccination rates. The guidelines encourage physicians to administer one dose of the adolescent-adult pertussis booster vaccine Tdap to anyone age 7 and older who is not fully immunized, including adults older than 64.

Doctors also should provide the booster to people who care for infants and to women of childbearing age -- either before they become pregnant, during their second or third trimester, or immediately after they give birth.

The CDPH recommendations differ from those issued by the CDC, which encourages doctors to administer one dose of Tdap to adults up to age 64.

Boosting California's immunization rates is one goal of proposed state legislation that would require health insurers to pay physicians for the full cost of purchasing, storing and administering immunizations. Proponents say it would enable doctors, particularly those in small practices, to afford the expenses associated with vaccinating patients.

A similar measure was introduced in 2009 but died in committee due to financial reasons, said Tom Riley, director of government relations for the California Academy of Family Physicians, which co-sponsored the bill. It was crafted before the latest outbreak.

Some health insurers have spoken out against the legislation. Susan Pisano, a spokeswoman for America's Health Insurance Plans, said studies indicate that the private sector already provides a fair return for doctor's vaccine costs.

But Sumana Reddy, MD, a family physician in a four-doctor practice in Salinas, Calif., disagreed. "We're trying to do what's right regardless. ... But in addition to not being reimbursed for the time we spend educating parents [and patients] about vaccines, we're putting money out for the cost of vaccines that isn't fully reimbursed. ... It's a hopeless proposition."

Vaccines not offered by some

Before widespread vaccination against pertussis, the disease infected as many as 147,000 people in the U.S. each year between 1940 and 1945 and killed nearly 8,000, according to the National Network for Immunization information.

By 1976, there were only 1,010 cases of whooping cough in the U.S., the lowest number ever reported. Since then, the incidence of pertussis has been rising, due in part to improved reporting of cases.

This year in California, pertussis incidence has been highest among infants younger than a year old, CDC figures show. Parents or other caregivers infected a majority of the children, according to Ken August, a spokesman for the California Dept. of Public Health. He said adults often are unaware that they have the disease, because their symptoms tend to be milder due to some level of immunity.

Immunization efforts have been further complicated by parents who are hesitant to have their children vaccinated, Dr. Reddy said. "We encounter lots of patients' families who are pretty clear that they're suspicious of vaccines. It's a frustrating issue, because these are often people ... who don't understand the possible effects of going without the pertussis or mumps vaccines."

There also are adults who have not received the Tdap booster vaccine, in part because some physicians choose not to offer it because of payment issues, Dr. Reddy said.

The financial challenges of vaccinating patients extend beyond California to doctors' offices across the country. A December 2008 Pediatrics study that surveyed 597 U.S. pediatricians and family physicians found that 49% of the doctors practiced in an office that had delayed purchasing a new vaccine due to financial concerns. Five percent of pediatricians and 21% of family physicians said they seriously considered discontinuing the immunization of privately insured patients in the past year because of vaccine costs, as well as administration and payment issues.

Any physician who does not offer needed vaccines must have some discussion with the patient or child's parent about their alternatives, said Arthur Caplan, PhD, a bioethics professor in the Dept. of Medical Ethics at the University of Pennsylvania. He also is director of the university's Center for Bioethics.

Caplan recommends that physicians offer the vaccines and bill patients for the costs not covered by insurers. If that is not possible, he suggests that doctors direct patients to other locations where they can receive the immunization. Some physicians are encouraging patients to receive certain vaccines at public health clinics.

The CDC is monitoring the California outbreak closely. The agency also is keeping an eye on a mumps resurgence in New York and New Jersey that has been spreading through largely Orthodox Jewish communities since June 2009. As of Jan. 29, 2010, 1,521 cases had been reported, according to the CDC. A majority of those infected received at least one of the two recommended doses of the measles, mumps and rubella vaccine. Dr. Clark said the CDC is worried about such recent resurgences of vaccine-preventable diseases.

"Any time there is a substantial increase in disease occurrence, there's cause for concern. Especially when it's causing children to be hospitalized," Dr. Clark said.

He added, "There shouldn't be children who die of pertussis."