Play Live Radio
Next Up:
Available On Air Stations
Watch Live


Immunized People Getting Whooping Cough, Experts Spar Over New Strain

Deaths attributed to pertussis have risen steadily since the late 1970s. The above chart shows the rise from 1982 to 2010.
Deaths attributed to pertussis have risen steadily since the late 1970s. The above chart shows the rise from 1982 to 2010.

Matthew Jacob Bryce was born a healthy 8 pounds, 9 ounces on Oct 11, 2010, so when he showed signs of a cold at just two weeks, his parents knew something more might be wrong. They were not first-time parents.

“He was just really stuffy. He was having difficulty breathing,” Marlon Bryce, Matthew’s father, recalled.

Immunized People Getting Whooping Cough, Experts Spar Over New Strain
Matthew Jacob Bryce was born a healthy baby boy, so when he showed signs of a cold at just two weeks, his parents knew something more might be wrong.

Marlon and Cindy Bryce

CDC Vaccine Recommendations

Young Children

DTaP is routinely recommended at 2, 4, and 6 months, at 15 through 18 months, and at 4 through 6 years.


Any adult 19 through 64 years of age who has not received a dose of Tdap should get one, which can replace one of the 10-year Td booster doses. However, it is not necessary to wait the typical 10 years to get the adult dose of Tdap after the last dose of Td.

The doctor suspected whooping cough, although everyone in the house had been vaccinated. For Marlon and Cindy Bryce, a young couple who had met in San Diego when both were in the Navy, it was a terrible prospect. Whooping cough, known also as pertussis, can be fatal in babies.

The doctor took a nasal swab, and started the infant on antibiotics.

It took six days to get the lab results. Matthew, at 23 days old, had pertussis.

California is experiencing its worst whooping cough outbreak in more than 60 years. Thousands of people have gotten sick and 10 infants have died, including two in San Diego County.


Health officials across the country are trumpeting pertussis vaccinations, but a four-month investigation by KPBS and the Watchdog Institute, a nonprofit investigative center based at San Diego State University, has found that many people who have come down with whooping cough have been immunized.

Two of the world’s most respected experts on the disease disagree about why there are such high numbers of people who are getting sick. Dr. James Cherry, a prominent researcher at UCLA, says increased awareness of whooping cough has led to more reports of it. However, Dr. Fritz Mooi, a well-known Dutch scientist who has been studying mutations of the pertussis bacteria for 15 years, says a more virulent strain of bacteria is contributing to outbreaks.

KPBS and the institute have been asking about the possibility of more virulent whooping cough strains for months, and the Centers for Disease Control and Prevention (CDC) recently announced studies of the disease, and the bacteria causing it, in California and Ohio. Two members of the California study group said it was prompted by the increasing death toll and KPBS-institute inquiries.

Story continues below.

Officials from the CDC, the California Department of Public Health (CDPH) and two pertussis experts from UCLA held a conference call Oct. 13 to discuss studying whether a more virulent strain was responsible for infant deaths and is contributing to the current epidemic. That same day, whooping cough claimed the life of its tenth newborn in California.

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, the scientist who has been studying the bacterial mutations, 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.

Dr. Frits Mooi

In examining the pertussis epidemic, KPBS and the Watchdog Institute collected federal, state and county statistics and consulted and interviewed experts from Los Angeles to the Netherlands.

Key findings include:

• 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 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 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.

Story continues below.

Cases of pertussis declined rapidly in the 1940s. The all-time low was in 1976, with only 75 cases reported in the United States. Since the early 1980s, there has been an increase in reported cases of whooping cough.
Cases of pertussis declined rapidly in the 1940s. The all-time low was in 1976, with only 75 cases reported in the United States. Since the early 1980s, there has been an increase in reported cases of whooping cough.

While public health officials and scientists agree that vaccines are still the best available tool against pertussis, they argue over how effective they are with time and in the face of a possible increase in virulence.

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 those 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.

At the Bryces’ home in Chula Vista, Marlon, who is 31 and a contract specialist at the Naval Medical Center, and Cindy, 27, puzzle over how Matthew could have contracted pertussis. He hadn’t been out of the house much, they said.

Their other boys Jordan, 4, and Joshua, 3, were up to date on their vaccinations. Marlon had gotten his a month before Matthew was born. Cindy was immunized before leaving the hospital after giving birth.

Marlon clearly remembers Cindy’s call when she learned Matthew had whooping cough. “She was crying … The moment that I heard it, I immediately started thinking the worst. You’ve heard the news about the babies that have passed away … Why is this happening?”

Marlon is soft-spoken and thoughtful.

“The one thing I would want to know is: Is the vaccine working? Is it as effective? … I thought that if I did everything I was told to do that our sons would be protected,” Marlon said.

The bacterium that causes whooping cough was first identified in 1906, when the illness was a common cause of death in infants and young children.

The discovery lead to the first attempts at a vaccine, but it wasn’t until the late 1940s, when the rate of disease was around 157 cases per 100,000 population, that scientists developed a vaccine effective enough to prevent pertussis. By the 1970s, the pertussis infection rate had dropped to less than one per 100,000.

But the vaccine, made of whole bacterial cells killed in labs, had side effects, such as prolonged crying spells in babies and seizures.

By 1996, the FDA approved a new whooping cough vaccine: an acellular version, which uses only purified components of the disease-causing organism. It is considered safer than the whole-cell vaccine and is the only one used in the U.S. today.

Just as the vaccines were changing, health officials across the country were reporting increasing numbers of whooping cough cases. According to a CDC report, most of the children four years old and younger who got whooping cough nationwide between 1990 and 1996 were not fully immunized.

That trend appears to have reversed in California’s latest outbreak.

KPBS and the Watchdog Institute requested information from 19 California counties most affected by pertussis. Nine counties supplied pertussis case information and vaccination history. In all but Stanislaus County, more than half the people sick with whooping cough had been immunized.

As of the end of October, and in cases where immunization history was known, data showed 83 percent of the people with whooping cough in Fresno had been vaccinated. In San Luis Obispo, 76 percent were up to date on their immunizations. In San Diego, 68 percent were up to date.

Public health experts say the surge of the disease is cyclical, with increased diagnoses every two to five years.

“And that tells us bordatella pertussis is circulating today exactly as it did in the prevaccine era,” Cherry said. “The main reason is increased awareness,” he explained. “People, particularly public health people, are much more aware, and that trickles down.”

Cherry and Mooi agree that immunity provided by vaccines wanes over time. But, they disagree over how long immunity lasts, and whether a mutated strain of pertussis is exploiting waning immunity.

Dr. James Cherry

Drug package inserts included with the two most common pertussis vaccines in the U.S. state they are 85 percent effective. Cherry, who was involved in the efficacy studies when the vaccines were licensed by the FDA, estimates the efficacy is between 70 and 80 percent. Mooi said there’s no way to know how effective the vaccines are because they haven’t been tested against the new strain.

“The vaccines have less efficacy than many people believe,” Mooi said.

Public health agencies recommend five vaccine doses by age 6, and they recommend adults get a booster every 10 years. The California state legislature passed a law in September requiring all children entering middle school to receive a pertussis booster.

Cherry advocates booster shots. Mooi isn’t so sure adult boosters are cost effective. Both agree that the current vaccine offers the best protection against the disease, especially for families with an infant in the house.

In the long run, Mooi says there should be better vaccines.

Money should be spent studying today’s strains and making a vaccine that would work against them, Mooi said. “After all, every year we have a new flu vaccine, so, I think we should have something like that for bacterial vaccines, too,” he said.

Cherry believes a new, better vaccine is a long way off.

“I think the likelihood of the logistics of getting a new vaccine right now in this country is almost impossible, because of the FDA rules and requirements,” he said. “There’s a lot of things you could do (to improve current vaccines), but to get it approved would cost billions of dollars.”

Cindy and Marlon Bryce were certainly aware of the deadly nature of whooping cough. Six weeks in October and November were harrowing for them. Today, their routine is more normal. Matthew has started day care.

“The one thing I would want to say to parents is watch your kids, just be concerned,” Marlon said. “At first we thought we were being overprotective. But I’m glad we were."

He continued, “I would just hope that there is something we can do about this. If there’s something that we can do, if there’s something that the scientists who look at these things every day, if they think that there’s a better way to do this, if there’s a way that they can improve this vaccine, then please. I would support it.”

Tomorrow - Blurred lines of influence: when pertussis experts rely on vaccine companies for money, ethical dilemmas abound.

Corrected: April 20, 2024 at 3:25 AM PDT
Freelancer reporter Roxana Popescu, Watchdog Institute intern Sandy Coronilla and KPBS Reeves Scholar Jessica Plautz contributed to this report. The Watchdog Institute is an independent nonprofit investigative journalism center, based at San Diego State University.