TDAP Vaccine During Pregnancy Protects Infants Against Whooping Cough

MedicalResearch.com Interview with:

Sylvia Becker-Dreps, MD MPH Associate Professor, Department of Family Medicine Associate Director, Office of International Activities (Latin America Focus) Director, UNC Program in Nicaragua University of North Carolina at Chapel Hill Chapel Hill, NC 27599-7595

Dr. Becker-Dreps

Sylvia Becker-Dreps, MD MPH
Associate Professor, Department of Family Medicine
Associate Director, Office of International Activities (Latin America Focus)
Director, UNC Program in Nicaragua
University of North Carolina at Chapel Hill
Chapel Hill, NC 27599-7595

MedicalResearch.com: What is the background for this study? What are the main findings?

 Response: Pertussis (or whooping cough) is a respiratory infection caused by bacteria. It has been becoming more common in the US over the past two decades. Infants are more likely to be hospitalized and die of the disease. They are especially vulnerable in the first months of life because they have not yet had time to complete the DTaP vaccine series themselves. (Currently, infants receive 3 doses of DTaP at 2,4, and 6 months of age.) Immunizing mothers allows the mothers to pass antibodies against pertussis through the placenta and provide passive immunity to infants early in life. In early 2013, the CDC recommended that pregnant women receive a Tdap vaccine in every pregnancy. That recommendation was based on studies of the immune response to the vaccine, not real cases of pertussis.

Our study examined clinical cases of pertussis in over 675,000 infants throughout the US. We found that in the first six months of life, infants of vaccinated mothers (those that received Tdap during pregnancy) had 75% less pertussis hospitalizations and 50% less pertussis cases overall.  Continue reading

End of Honeymoon Period Means Whooping Cough Can Resurge

MedicalResearch.com Interview with:

This Gram-stained photomicrograph depicts numbers of Bordetella pertussis bacteria, which is the etiologic pathogen for pertussis, also known as whooping cough.

This Gram-stained photomicrograph depicts numbers of Bordetella pertussis bacteria, which is the etiologic pathogen for pertussis, also known as whooping cough.
CDC image

Matthieu Domenech de Cellès PhD
Department of Ecology and Evolutionary Biology
University of Michigan, Ann Arbor, MI, USA.
Biostatistics, Biomathematics, Pharmacoepidemiology, and Infectious Diseases Unit
Institut Pasteur, Inserm,
University of Versailles St-Quentin-en-Yvelines,
Versailles, France.

MedicalResearch.com: What is the background for this study? What are the main findings?

 

Response: Our main motivation was to elucidate an apparent paradox: Why has the US experienced a resurgence of pertussis (whooping cough) since the mid-1970s, despite persistently high vaccine coverage? A variety of hypotheses have been proposed to explain this resurgence, but most attention has focused on the potential shortcomings of the new generation of pertussis vaccines (called acellular pertussis vaccines). However, there remains considerable uncertainty about the degree and the mechanisms of protection conferred by pertussis vaccines.

Via a collaboration with the local department of public health, we used detailed surveillance data in the state of Massachusetts to test a number of hypotheses about pertussis vaccines. We found that, although pertussis vaccines are imperfect (in the sense that they do not provide lifelong, 100% protection to 100% of children vaccinated), they are still highly efficacious. Specifically, we estimated that vaccine protection wanes over time, but slowly, with about 85% of children still protected 10 years after vaccination. Despite this high vaccine efficacy, we showed that the resurgence of pertussis was, in fact, to be expected. What happens is that the introduction of routine vaccination leads to an overall reduction in transmission, not only in vaccinated children but also in the population at large. Accordingly, those who escaped vaccination as children (as a consequence of incomplete vaccine coverage or imperfect vaccine protection) increasingly age having also avoided natural infection. As a result, the number of individuals susceptible to contract pertussis gradually increases. Because such people are the “fuel” of epidemics, this sets the stage for pertussis’ resurgence, with increasing incidence among older individuals.

This overall effect is called the “end-of-honeymoon” and means that resurgence is therefore a predictable consequence of incomplete vaccination with efficacious, but imperfect, vaccines. Importantly, these results show that recent trends do not necessarily reflect recent changes in the epidemiology of pertussis. Rather, they may be interpreted as a legacy of past immunization practices, with long-to-manifest effects. This is a significant shift of perspective about pertussis epidemiology.  Continue reading

TDAP Vaccine During Pregnancy Prevents Whooping Cough In Young Babies

MedicalResearch.com Interview with:
Tami H Skoff Centers for Disease Control and Prevention Atlanta, Georgia
Tami H Skoff
Centers for Disease Control and Prevention
Atlanta, Georgia

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Infants are at greatest risk for severe pertussis (whooping cough) morbidity and mortality, especially during the first months of life before infant immunizations begin.  CDC and the Advisory Committee on Immunization Practices (ACIP) currently recommend that women receive a dose of Tdap during the third trimester of each pregnancy.  This recommendation has been in place since 2012.  By getting Tdap, pregnant women pass critical short-term protection to their unborn babies. This helps protect babies until they are old enough to start getting their own whooping cough vaccines at 2 months of age.

The purpose of our study was to evaluate the effectiveness of maternal Tdap during pregnancy at preventing whooping cough in infants <2 months of age.

In our evaluation, Tdap administration during the third trimester of pregnancy prevented more than 3 in 4 (78%) infant cases.  Additionally, Tdap vaccination during pregnancy was even more effective (90%) at preventing whooping cough serious enough that the baby had to get treatment in a hospital.

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Whooping Cough Can Still Cause Significant Cough Even In Fully Vaccinated Children

Kay Wang Academic Clinical Lecturer Nuffield Department of Primary Care Health Sciences University of Oxford, Oxford, UKMedicalResearch.com: Interview with
Kay Wang
Academic Clinical Lecturer
Nuffield Department of Primary Care Health Sciences
University of Oxford, Oxford, UK


MedicalResearch: What are the main findings of the study?

Dr. Wang: We have found evidence of recent whooping cough infection in 1 in 5 school age children who see their doctor with a persistent cough and in 1 in 6 children who have been fully vaccinated against whooping cough.  We have also shown that whooping cough can still cause clinically significant cough in fully vaccinated children.
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