Our Vaccine Update feature article “Fast Facts” series continues this month with a focus on pertussis, also known as whooping cough. Approximately 35,000 cases were recorded during 2024, an increase from pre-pandemic levels in 2019, and a likely underestimate, as is often the case when it comes to pertussis. Because immunity to pertussis wanes after either vaccination or natural infection, this disease typically circulates at low levels. More recently, waning immunity has been compounded by decreases in vaccination rates, putting the most vulnerable — the youngest infants — at risk. In 2024, 10 deaths occurred; six of these were in infants younger than 1 year of age. In April 2025, Louisiana reported two deaths in infants in just six months’ time.
Recognizing pertussis
Pertussis is challenging to recognize early in infection because initial symptoms are like those of a typical cold. However, pertussis typically progresses through three stages, making diagnosis easier as illness continues:
- Catarrhal stage (first 1-2 weeks): Early symptoms of pertussis are similar to a common cold with mild cough, runny nose and low-grade fever. People at this stage of infection are contagious but lack an obvious clinical finding to help providers know to test. A known exposure or significant disease in the community may be the only clue.
- Paroxysmal stage (1-6 weeks): In this stage, people have classic fits of coughing followed by a “whoop” sound, cough-induced vomiting and exhaustion. Older children and adults may have a less prominent “whoop” or merely a persistent cough. Coughing spells can occur up to 15 times per day and can be so severe that they lead to broken blood vessels, including nosebleeds, broken ribs, and hernias, in which organs break through muscle or tissue walls. Infants may experience apnea (short periods in which they stop breathing), cyanosis (bluish skin tone due to low oxygen levels) or gagging, often without a whoop. The apnea and cyanosis can be life-threatening.
- Convalescent stage (weeks to months): People are no longer contagious during this stage, but recovery occurs slowly. This stage often lasts three months or longer as cough slowly resolves.
Clinicians should have a high index of suspicion early on, particularly when pertussis is circulating in the community.
Infants under 12 months are at greatest risk for hospitalization and death from pertussis. Adolescents and adults are a major source of transmission to vulnerable infants.
Making a pertussis diagnosis
PCR testing of nasopharyngeal specimens is the most sensitive and commonly used test, especially in the first few weeks of illness. Early testing is critical as early treatment may decrease severity of illness as well as reduce transmission to others. However, because the infection may be mild in older children and adults, many will not seek medical care, leading to underdiagnosis. Alternatively, people with mild illness may see a clinician but be misdiagnosed as having a viral illness or other disease where cough is a prominent symptom, like an asthma flare or pneumonia.
Treatment and management of pertussis
Antibiotics will reduce spread to other people by preventing additional bacterial replication and may make the infection less severe for the patient if started during the catarrhal stage (first 1-2 weeks). Most people remain contagious in the first three weeks of symptoms and should start antibiotics if diagnosed during that time period. They should also isolate for the first five days of treatment. Of note, pregnant people and infants up to 1 year of age may be given antibiotics up to six weeks after the start of symptoms. This recommendation is made out of an abundance of caution for these two populations. For pregnant people, treatment is critical as they are going to be in close contact with an infant in the near future. For infants, disease is so severe that even a small benefit from late therapy may be lifesaving.
A macrolide antibiotic, typically azithromycin or erythromycin, is preferred for most age groups. After five days of antibiotic treatment, people are no longer contagious and can return to normal routines. Without antibiotics, people should be considered contagious for 21 days and advised to isolate during that time. Erythromycin and azithromycin should be prescribed with caution in young infants because of their association with the development of infantile hypertrophic pyloric stenosis (IHPS), a rare condition in young infants in which a thickening of the muscles connecting the stomach and the intestine blocks food from passing through the digestive tract. IHPS can lead to vomiting, constipation, dehydration and weight loss and requires surgical intervention to relieve.
Supportive care during infection is often necessary for infants with pertussis. Some require hospitalization, sometimes including intensive care, particularly if they develop apnea or pneumonia (infection of the lungs). Monitoring and managing oxygen levels, eating habits and hydration are key components of care. Older children and adults may need care if they suffer complications, such as a broken rib, hernia or pneumonia.
Long-term impact
Although most people recover, pertussis can have serious outcomes. About 1 in 100 infants younger than 3 months of age with pertussis will die. While rare, some infants will have seizures or brain injury due to low oxygen levels during coughing fits. Older children and adults may experience complications from coughing, including broken ribs, hernia, pneumonia and weight loss. After the infection, they may experience prolonged fatigue.
Infection control: Reducing the spread of pertussis
Pertussis is highly contagious and spreads through respiratory droplets. Patients are most infectious in the catarrhal (first) stage and during the first two weeks of coughing. In a healthcare setting, the biggest risk is spread from patients to providers, such as if a provider collects a respiratory specimen without wearing a mask. For this reason, providers should use droplet precautions (masks) based on a patient’s symptoms of mild cough and runny nose even before a diagnosis has been made. If pertussis is confirmed, droplet precautions should continue until the patient has received five days of antibiotics.
Antibiotic prophylaxis is recommended for close contacts, especially infants, pregnant individuals, and people who will be in close contact with infants. Maternal vaccination with pertussis vaccine during pregnancy remains the most effective way to prevent infection in infants as it reduces the likelihood that a new mother will transmit pertussis to her baby in the days after birth. Likewise, maternal vaccination will provide passive protection to the infant through transient antibodies that cross the placenta prior to birth.
Finally, it’s important to remember that pertussis is a reportable disease, and public health departments may coordinate broader interventions during outbreaks in schools or child care centers.
Pertussis: Key clinical takeaways
Pertussis is one of the more common vaccine-preventable diseases that circulates in the U.S., with infants at the greatest risk for severe outcomes. Recognizing the early signs and acting quickly to test for pertussis can help decrease the spread of this highly contagious infection.
Resources for families
- Diphtheria, Tetanus and Pertussis: The Disease & Vaccines (webpage)
- Pertussis Q&A: What You Should Know: English | Spanish (PDF)
- Vaccines on the Go: What You Should Know (mobile app)
- Doctors Talk: Pertussis in Children and Adults (video)
- If I got the whooping cough vaccine during pregnancy, should I delay my baby’s DTaP vaccine? (video)
- Which adults need a Tdap vaccine? (video)
- Vaccines During Pregnancy: English | Spanish (infographic)
- Infectious Diseases and Pregnancy: What You Should Know (PDF)
Resources for providers
- Manual for the Surveillance of Vaccine-Preventable Diseases — Chapter 10: Pertussis (webpage)
- Infection Control: Pertussis (webpage)
Contributed by: Lori Handy, MD, MSCE , Charlotte A. Moser, MS, Paul A. Offit, MD
Our Vaccine Update feature article “Fast Facts” series continues this month with a focus on pertussis, also known as whooping cough. Approximately 35,000 cases were recorded during 2024, an increase from pre-pandemic levels in 2019, and a likely underestimate, as is often the case when it comes to pertussis. Because immunity to pertussis wanes after either vaccination or natural infection, this disease typically circulates at low levels. More recently, waning immunity has been compounded by decreases in vaccination rates, putting the most vulnerable — the youngest infants — at risk. In 2024, 10 deaths occurred; six of these were in infants younger than 1 year of age. In April 2025, Louisiana reported two deaths in infants in just six months’ time.
Recognizing pertussis
Pertussis is challenging to recognize early in infection because initial symptoms are like those of a typical cold. However, pertussis typically progresses through three stages, making diagnosis easier as illness continues:
- Catarrhal stage (first 1-2 weeks): Early symptoms of pertussis are similar to a common cold with mild cough, runny nose and low-grade fever. People at this stage of infection are contagious but lack an obvious clinical finding to help providers know to test. A known exposure or significant disease in the community may be the only clue.
- Paroxysmal stage (1-6 weeks): In this stage, people have classic fits of coughing followed by a “whoop” sound, cough-induced vomiting and exhaustion. Older children and adults may have a less prominent “whoop” or merely a persistent cough. Coughing spells can occur up to 15 times per day and can be so severe that they lead to broken blood vessels, including nosebleeds, broken ribs, and hernias, in which organs break through muscle or tissue walls. Infants may experience apnea (short periods in which they stop breathing), cyanosis (bluish skin tone due to low oxygen levels) or gagging, often without a whoop. The apnea and cyanosis can be life-threatening.
- Convalescent stage (weeks to months): People are no longer contagious during this stage, but recovery occurs slowly. This stage often lasts three months or longer as cough slowly resolves.
Clinicians should have a high index of suspicion early on, particularly when pertussis is circulating in the community.
Infants under 12 months are at greatest risk for hospitalization and death from pertussis. Adolescents and adults are a major source of transmission to vulnerable infants.
Making a pertussis diagnosis
PCR testing of nasopharyngeal specimens is the most sensitive and commonly used test, especially in the first few weeks of illness. Early testing is critical as early treatment may decrease severity of illness as well as reduce transmission to others. However, because the infection may be mild in older children and adults, many will not seek medical care, leading to underdiagnosis. Alternatively, people with mild illness may see a clinician but be misdiagnosed as having a viral illness or other disease where cough is a prominent symptom, like an asthma flare or pneumonia.
Treatment and management of pertussis
Antibiotics will reduce spread to other people by preventing additional bacterial replication and may make the infection less severe for the patient if started during the catarrhal stage (first 1-2 weeks). Most people remain contagious in the first three weeks of symptoms and should start antibiotics if diagnosed during that time period. They should also isolate for the first five days of treatment. Of note, pregnant people and infants up to 1 year of age may be given antibiotics up to six weeks after the start of symptoms. This recommendation is made out of an abundance of caution for these two populations. For pregnant people, treatment is critical as they are going to be in close contact with an infant in the near future. For infants, disease is so severe that even a small benefit from late therapy may be lifesaving.
A macrolide antibiotic, typically azithromycin or erythromycin, is preferred for most age groups. After five days of antibiotic treatment, people are no longer contagious and can return to normal routines. Without antibiotics, people should be considered contagious for 21 days and advised to isolate during that time. Erythromycin and azithromycin should be prescribed with caution in young infants because of their association with the development of infantile hypertrophic pyloric stenosis (IHPS), a rare condition in young infants in which a thickening of the muscles connecting the stomach and the intestine blocks food from passing through the digestive tract. IHPS can lead to vomiting, constipation, dehydration and weight loss and requires surgical intervention to relieve.
Supportive care during infection is often necessary for infants with pertussis. Some require hospitalization, sometimes including intensive care, particularly if they develop apnea or pneumonia (infection of the lungs). Monitoring and managing oxygen levels, eating habits and hydration are key components of care. Older children and adults may need care if they suffer complications, such as a broken rib, hernia or pneumonia.
Long-term impact
Although most people recover, pertussis can have serious outcomes. About 1 in 100 infants younger than 3 months of age with pertussis will die. While rare, some infants will have seizures or brain injury due to low oxygen levels during coughing fits. Older children and adults may experience complications from coughing, including broken ribs, hernia, pneumonia and weight loss. After the infection, they may experience prolonged fatigue.
Infection control: Reducing the spread of pertussis
Pertussis is highly contagious and spreads through respiratory droplets. Patients are most infectious in the catarrhal (first) stage and during the first two weeks of coughing. In a healthcare setting, the biggest risk is spread from patients to providers, such as if a provider collects a respiratory specimen without wearing a mask. For this reason, providers should use droplet precautions (masks) based on a patient’s symptoms of mild cough and runny nose even before a diagnosis has been made. If pertussis is confirmed, droplet precautions should continue until the patient has received five days of antibiotics.
Antibiotic prophylaxis is recommended for close contacts, especially infants, pregnant individuals, and people who will be in close contact with infants. Maternal vaccination with pertussis vaccine during pregnancy remains the most effective way to prevent infection in infants as it reduces the likelihood that a new mother will transmit pertussis to her baby in the days after birth. Likewise, maternal vaccination will provide passive protection to the infant through transient antibodies that cross the placenta prior to birth.
Finally, it’s important to remember that pertussis is a reportable disease, and public health departments may coordinate broader interventions during outbreaks in schools or child care centers.
Pertussis: Key clinical takeaways
Pertussis is one of the more common vaccine-preventable diseases that circulates in the U.S., with infants at the greatest risk for severe outcomes. Recognizing the early signs and acting quickly to test for pertussis can help decrease the spread of this highly contagious infection.
Resources for families
- Diphtheria, Tetanus and Pertussis: The Disease & Vaccines (webpage)
- Pertussis Q&A: What You Should Know: English | Spanish (PDF)
- Vaccines on the Go: What You Should Know (mobile app)
- Doctors Talk: Pertussis in Children and Adults (video)
- If I got the whooping cough vaccine during pregnancy, should I delay my baby’s DTaP vaccine? (video)
- Which adults need a Tdap vaccine? (video)
- Vaccines During Pregnancy: English | Spanish (infographic)
- Infectious Diseases and Pregnancy: What You Should Know (PDF)
Resources for providers
- Manual for the Surveillance of Vaccine-Preventable Diseases — Chapter 10: Pertussis (webpage)
- Infection Control: Pertussis (webpage)
Contributed by: Lori Handy, MD, MSCE , Charlotte A. Moser, MS, Paul A. Offit, MD