MONDAY, March 11 (HealthDay News) -- 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 dose is
New research from the U.S. Centers for Disease Control and
Prevention (CDC) confirms what other recent studies have found:
protection against whooping cough wanes significantly between the
fifth dose of the vaccine -- given sometime during the 4- to
6-year-old age range -- and the adolescent booster vaccine given at
11 or 12.
"This study provides fairly strong evidence that the trends we're seeing are real -- and a couple of other studies with similar findings have recently come out," said study lead author Sara Tartof, who was at the CDC at the time of the study and is now a researcher at Kaiser Permanente in Los Angeles.
Nonetheless, "the vaccine is still a great tool," she said.
"Kids who are fully vaccinated who get whooping cough have a much
milder disease than those who aren't vaccinated. Vaccines are still
the best protection against disease, and the incidence of whooping
cough is low."
Whooping cough, which is also called pertussis, is a highly
contagious bacterial disease that attacks the respiratory system.
In 2012, the United States had the highest number of whooping cough
cases since 1959, according to the CDC. During 2012, the CDC
received reports of 41,000 cases and 18 deaths, with most of the
deaths occurring in infants.
The whooping cough vaccine also includes immunizations for
diphtheria and tetanus. It's given in a five-dose series at 2, 4
and 6 months; at 15 to 18 months; and between 4 and 6 years,
according to the CDC. An adolescent booster is recommended between
age 11 and 12.
The current study, published online March 11 in the journal
Pediatrics, looked at children born between 1998 and 2003 in
Minnesota or Oregon who had received the recommended five doses of
the vaccine. By using immunization records and comparing them to
state health department whooping cough surveillance data for six
years following the fifth dose of vaccine, the researchers were
able to more accurately track how many fully vaccinated youngsters
got the illness, and how much protection the vaccine offered from
year to year.
In Minnesota, nearly 225,000 children born during the study
period were fully vaccinated. In Oregon, there were about 180,000.
In Minnesota, 458 cases of whooping cough were reported; there were
89 reported in Oregon.
The rates of whooping cough rose each year of the follow-up
period. During the first year after the final vaccination, the
incidence of whooping cough was 15.6 per 100,000 in the Minnesota
population. By the sixth year, that rate was 138.4 per 100,000. In
Oregon, a similar trend emerged, with a rate of 6.2 per 100,000 in
the first year of follow-up and 24.4 per 100,000 in the last year
The authors said many reasons may explain why whooping cough
cases are on the rise. One may be that physicians simply are more
aware of the disease and may be reporting it more often. Another
possible cause is the vaccine itself, they noted.
The current vaccine is an acellular vaccine, which means it
doesn't contain whole cells of the bacterium responsible for
pertussis infections. The previous vaccine contained whole cells of
the bacterium, but was more likely to cause side effects. One of
the trade-offs for reducing side effects may be a vaccine that's
slightly less effective, said Dr. Kenneth Bromberg, director of the
Vaccine Research Center at the Brooklyn Hospital Center in New York
"This study adds to the strength of argument that the acellular vaccine doesn't seem to last as long as we might have thought it would," Bromberg said.
Both experts said there are no new whooping cough vaccines
currently in development, so for now it's important that everyone
get vaccinated: children, teens and adults. The more people who
have protection against the disease, the less chance it will have
That's why the CDC now recommends that pregnant women receive
the whooping cough vaccine during the third month of pregnancy, so
they can pass protection on to their babies.
To learn more about whooping cough, visit the
Centers for Disease Control and Prevention.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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