FDA study helps provide an understanding of rising rates of whooping cough and response to vaccination
FDA NEWS RELEASE
For Immediate Release: Nov. 27, 2013
Media Inquiries: FDA- Jennifer Rodriguez, 301-796-8232, jennifer.rodriguez@fda.hhs.gov
NIH- Nalini Padmanabhan, 301-402-1663, padmanabhannm@niaid.nih.gov
NIH- Nalini Padmanabhan, 301-402-1663, padmanabhannm@niaid.nih.gov
Consumer Inquiries: 888-INFO-FDA,OCOD@fda.hhs.gov
FDA study helps provide an understanding of rising rates of whooping cough and response to vaccination
A
new study is helping to provide a better understanding of vaccines for
whooping cough, the common name for the disease pertussis. Based on an
animal model, the study conducted by the U.S. Food and Drug
Administration (FDA) and published November 25, 2013, in The Proceedings of the National Academy of Sciences,
shows that acellular pertussis vaccines licensed by the FDA are
effective in preventing the disease among those vaccinated, but suggests
that they may not prevent infection from the bacteria that causes
whooping cough in those vaccinated or its spread to other people,
including those who may not be vaccinated.
Whooping
cough rates in the United States have been increasing since the 1980s
and reached a 50-year high in 2012. Whooping cough is a contagious
respiratory disease caused by Bordetella pertussis bacteria.
Initial symptoms include runny nose, sneezing, and a mild cough, which
may seem like a typical cold. Usually, the cough slowly becomes more
severe, and eventually the patient may experience bouts of rapid,
violent coughing followed by the “whooping” sound that gives the disease
its common name, when trying to take a breath. Whooping cough can cause
serious and sometimes life-threatening complications, permanent
disability, and even death, especially in infants and young children.
There
are two types of pertussis vaccines, whole-cell and acellular.
Whole-cell pertussis vaccines contain a whole-cell preparation, which
means they contain killed, but complete, B. pertussis bacteria.
The acellular pertussis vaccine is more purified and uses only selected
portions of the pertussis bacteria to stimulate an immune response in an
individual. In response to concerns about the side effects of the whole
cell pertussis vaccine, acellular vaccines were developed and replaced
the use of whole-cell pertussis vaccines in the U.S. and other countries
in the 1990s; however, whole-cell pertussis vaccines are still used in
many other countries.
“This study is critically
important to understanding some of the reasons for the rising rates of
pertussis and informing potential strategies to address this public
health concern,” said Karen Midthun, M.D., director of the FDA’s Center
for Biologics Evaluation and Research, where the study was conducted.
“This research is a valuable contribution and brings us one step closer
to understanding the problem. We are optimistic that more research on
pertussis will lead to the identification of new and improved methods
for preventing the disease.”
While the reasons for
the increase in cases of whooping cough are not fully understood,
multiple factors are likely involved, including diminished immunity from
childhood pertussis vaccines, improved diagnostic testing, and
increased reporting. With its own funds plus support from the National
Institutes of Health (NIH), the FDA conducted the study to explore the
possibility that acellular pertussis vaccines, while protecting against
disease, might not prevent infection.
“There were
48,000 cases reported last year despite high rates of vaccination,” said
Anthony S. Fauci, M.D., director of the NIH’s National Institute of
Allergy and Infectious Diseases. “This resurgence suggests a need for
research into the causes behind the increase in infections and improved
ways to prevent the disease from spreading.”
The
FDA conducted the study in baboons, an animal model that closely
reproduces the way whooping cough affects people. The scientists
vaccinated two groups of baboons – one group with a whole-cell pertussis
vaccine and the other group with an acellular pertussis vaccine
currently used in the U. S. The animals were vaccinated at ages two,
four, and six months, simulating the infant immunization schedule. The
results of the FDA study found that both types of vaccines generated
robust antibody responses in the animals, and none of the vaccinated
animals developed outward signs of pertussis disease after being exposed
to B. pertussis. However, there were differences in other
aspects of the immune response. Animals that received an acellular
pertussis vaccine had the bacteria in their airways for up to six weeks
and were able to spread the infection to unvaccinated animals. In
contrast, animals that received whole-cell vaccine cleared the bacteria
within three weeks.
This research suggests that
although individuals immunized with an acellular pertussis vaccine may
be protected from disease, they may still become infected with the
bacteria without always getting sick and are able to spread infection to
others, including young infants who are susceptible to pertussis
disease.
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