Diseases > Pertussis
Pertussis Disease
"Whooping Cough"

Questions and answers for parents, health care professionals, and people considering immunization

1. Why do we vaccinate against “whooping cough” or pertussis?
2. How many cases of pertussis are reported in the United States?
3. Is pertussis reporting on the rise in the U.S.?
4. Why are we concerned about pertussis among infants?
5. How much has pertussis increased in reporting among infants in the U.S.?
6. Is there a change in the severity of pertussis in infants?
7. What can we do to prevent infants from getting pertussis?
8. What is the recommended immunization schedule with DTaP to prevent pertussis?

1. Why do we vaccinate against pertussis (also called “whooping cough”)?

Pertussis is a bacterial respiratory illness characterized by severe spasms of coughing that can last for several weeks or even for months. Pertussis is usually spread from person-to-person through close contact with respiratory droplets released when a person coughs or sneezes. Before the introduction of vaccination in the 1940s, pertussis was a major cause of serious illness and death among infants and young children in the United States.

2. How many cases of pertussis are reported in the United States?

An average of more than 160,000 cases and more than 5,000 deaths were reported every year in the 1920s-30s. At its peak during this period, the annual number of case-reports was more than 250,000 with up to 9,000 deaths. In the 1940s, whole-cell pertussis vaccine combined with diphtheria and tetanus toxoids (DTP) was introduced, and case-reports of pertussis decreased more than 99% by 1976, when the number of reported cases reached a record-low of 1,010 cases.

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3. Is pertussis reporting on the rise in the U.S.?

An increasing number of cases of pertussis have been reported to the CDC since the 1980s. The increases are greatest among adolescents (aged 10-19 years), but an increase is also seen among infants younger than 5 months old. The reported increases may reflect greater awareness of pertussis to some degree. Even with the increase in reports among adolescents and very young infants, the number of reported cases is more than 97 % lower than in the pre-vaccine era.

4. Why are we concerned about pertussis among infants? 

Infants under the age of 12 months have more serious illness from pertussis and they are more likely to have complications and be hospitalized than persons in other age groups. In the 1990s, about two thirds of infants reported with pertussis were hospitalized. Infants are more likely to have pneumonia or convulsions. Infants also are at greatest risk of fatal pertussis. In recent years, 15 to 21 infant deaths from pertussis are reported to CDC annually. 

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5. How much has the reporting of pertussis among infants increased in the U.S.?

The case-reports of pertussis among infants younger than 5 months have been increasing since the 1980s. This age group is too young to be well protected by DTaP (diphtheria and tetanus toxoids and acellular pertussis) vaccine. For example, the number of case-reports among infants younger than 5 months was about 600 per year in the early 1980s, and about 1,700 per year at the end of the 1990s. The average reported rate among infants in this age group increased more than 50% in the 1990s compared with the 1980s (the average reported rate was 89 in the 1990s per 100,000 infants). By contrast, among infants aged 5 to 11 months, there was no increase in the reported rate from the 1980s to the present.

(Data from Supplementary Pertussis Surveillance System).

6. Has there been a change in the severity of pertussis in infants?

No. The severity of the pertussis illness among reported infant cases was comparable between the 1980s and the 1990s, judging from reported symptoms and the proportion of patients hospitalized. Although the number of cases reported among infants younger than 5 months increased, the illnesses were just as serious as they were in the past.

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7. What can we do to prevent infants from getting pertussis?

In the U.S., we have the vaccine called DTaP (diphtheria and tetanus toxoids and acellular pertussis vaccine). DTaP is safe and effective, and prevents severe pertussis and death among infants and young children. The best way to protect infants from pertussis is to give DTaP vaccine starting on time at 2 months of age. Parents should vaccinate their infant on-time (at 2, 4, and 6 months of age) and complete all the recommended doses of DTaP vaccine to best protect their infant.

At least three DTaP doses are needed to have the maximum benefit from the vaccination. However, even one or two doses of DTaP will provide some protection against pertussis. Parents are urged to make sure their infant receives these doses on time.

Parents can also help protect their very young infants by minimizing exposure (close contact) with persons who have cold symptoms or cough illness. Coughing people of any age, including parents, siblings and grandparents can have pertussis. When a person has cold symptoms or cough illness, they need to stay away from young infants as much as possible.

8. What is the recommended immunization schedule to prevent pertussis with DTaP?

DTaP (diphtheria and tetanus toxoids and acellular pertussis) vaccine is recommended for all infants at 2, 4 and 6 months of age. An additional dose of DTaP vaccine is recommended at 15-18 months of age and at 4-6 years of age. It is important that young infants start their DTaP vaccination without delay at 2 months of age.

For more information on pertussis, consult: http://www.cdc.gov/nip/menus/diseases.htm#pertussis.

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This page last modified on December 9, 2003