REGION: Two-thirds of local pertussis cases were vaccinated, data show

Expert says whopping cough mutating, becoming more infectious

By JOANNE FARYON, KPBS, and KEVIN CROWE, Watchdog Institute North County Times - Californian | Posted: Wednesday, December 15, 2010 7:13 pm

As California experiences its worst whooping cough outbreak in more than 60 years, health officials across the country trumpet vaccinations to protect against the disease.

The number of cases of the disease in San Diego County this year has reached a record 1,046 as of mid-December and may triple the region's previous record by year's end, according to the county Department of Health and Human Services.

Data collected from around this state and several others show that many people who have come down with whooping cough had been immunized....

Dr. Jeff Miller, a scientist involved in the study at UCLA, said the possibility that the pertussis bacterium has mutated "is an important hypothesis to test." He added, "I wish we would have started it in 2005."

Mooi said his research has been ignored by those who influence public policy on pertussis in the U.S. and beyond in part because they rely on vaccine makers to fund their meetings and research.

There is little incentive for pharmaceutical companies to pursue a new vaccine because it would cost billions, he said. The circulation of a more virulent strain of pertussis could mean a new vaccine should be created.

In their four-month investigation of the pertussis epidemic, KPBS and the institute found:

-- For pertussis cases in which vaccination histories are known, between 44 and 83 percent were of people who had been immunized, according to data from nine California counties with high infection rates. In San Diego County, more than two-thirds of the people in this group were up to date on their immunizations.

-- Health officials in Ohio and Texas, two other states also experiencing whooping cough outbreaks, report that of all cases, 75 and 67.5 percent respectively, reported having received a pertussis vaccination.

-- Today, the rate of the disease in some California counties is as high as 139 per 100,000, rivaling rates before vaccines were developed.

-- Public officials around the world rely heavily on two groups of pertussis experts when setting vaccine policy relating to the disease. Both groups, and many of their members, receive money from the two leading manufacturers of pertussis vaccine.

Pertussis is a highly contagious respiratory illness that may mimic a cold for the first 10 days. It then can produce a violent and persistent cough with a unique "whooping" sound.

For adults, pertussis may only be a nuisance, like a bad cold. But to infants it can be deadly because they can't cough up what collects in their lungs and infections can spread.

Vaccinations nearly wiped out whooping cough more than 30 years ago. But it has made a vengeful comeback in California and other highly vaccinated communities around the U.S.

Dr. Mark Horton, director of the California Department of Public Health, said health officials expect to see a certain percentage of people who have been vaccinated contracting whooping cough. He says no vaccine is 100 percent effective, and those who are immunized and getting sick are likely to be people for whom the vaccine did not work or whose immunity has waned.

"That's no surprise to us," he said, "nor is it a reflection on the efficacy of the vaccine."

Mooi, who heads the Pertussis Surveillance Project at the National Institute of Health in the Netherlands, said an epidemic in 1996 in his country gave the need for research more urgency.

"And we found really a kind of new mutation in that bug," Mooi said. In tests, Mooi's lab found the mutated strain produced more toxins, which could make people sicker.....

It's a long article, but worth the read: