Our Vaccine Update feature article “Fast Facts” series continues this month with a focus on Haemophilus influenzae type b (Hib). With more families refusing or delaying routine vaccinations, healthcare providers are more frequently faced with the need to evaluate and manage unvaccinated children in their practice. One of the more common questions our infectious disease colleagues are asked is, “Should I be worried about something like meningitis in this unvaccinated child?”.
Prior to availability of the Hib vaccine, about 20,000 cases of invasive Hib disease occurred each year in the U.S. This plummeted by 99% with widespread use of the vaccine. The Hib vaccine not only reduced the risk of disease, but it also reduced colonization in the throat, decreasing spread in the community as well as cases among unvaccinated people. Importantly, vaccination rates need to remain above approximately 90% in infants and toddlers — the groups that drive transmission — to maintain these community benefits, more commonly referred to as herd immunity.
Recognizing Hib
Children with Hib infections can have an array of symptoms. Most feared is meningitis (swelling of the brain). Children with meningitis have classic symptoms like fever, irritability, lack of appetite, stiff neck and drowsiness. Infants may have a bulging fontanelle. Symptoms can progress to coma and death.
But Hib doesn’t just cause meningitis. It can also cause:
- Sepsis (bloodstream infections)
- Pneumonia (infection of the lungs)
- Cellulitis (infection of the skin; for Hib, a common location involves the side of the cheek)
- Arthritis (infection of the joints)
- Epiglottitis (infection and swelling of the tissue above the airway)
Hib, therefore, needs to be considered as a cause of any of these syndromes in unvaccinated children.
Making a Hib diagnosis
Depending on the patient’s syndrome, different tests may be required. If evaluating for meningitis, a lumbar puncture is needed for a gram stain (looking for small gram-negative coccobacilli), white blood cell count, measurements of protein (which will be high) and glucose (which will be low). Many multiplex PCR panels for meningitis include testing for Hib; alternatively, the diagnosis can be confirmed through culturing spinal fluid.
Clinicians continue to routinely see syndromes such as sepsis, pneumonia, cellulitis and arthritis caused by many types of viruses and bacteria. While the evaluation of an unvaccinated child does not need to change for these conditions, clinicians should consider Hib as a cause of these illnesses in unvaccinated children as this will impact the choice of antibiotic for treatment.
Treatment & management of Hib
Antibiotics are the primary method of treatment for Hib. Clinicians should recognize that empiric antibiotics, the antibiotics administered when a culture isn’t taken or available yet, need to cover Hib in unvaccinated children. In the cases where a culture is not obtained, the child’s immunization status may be a major driver in determining the plan for antibiotics. Clinical guidelines in the vaccine era highlight the need to consider a patient’s vaccination status when making empiric treatment decisions. For example, first line treatment for community-acquired pneumonia in children is amoxicillin, but many strains of Hib will not respond to this antibiotic, instead requiring a broader antibiotic like amoxicillin-clavulanic acid. This can be used for other infections, like sinusitis or ear infections, where Hib can cause infection.
Depending on the patient’s illness, the supportive care required until antibiotics take effect can vary greatly. For example, some children with pneumonia may be treated at home; others may need admission for oxygen — or worse, intubation. In contrast, sepsis, meningitis and epiglottitis are all medical emergencies and universally should be treated emergently in the hospital setting with intravenous antibiotics while waiting for results of initial testing. Third-generation cephalosporins, such as ceftriaxone, are commonly used in the emergency room or hospital for serious infections, like meningitis, bloodstream infections or epiglottitis. Despite early antibiotic treatment, not all infections are survivable.
Long-term impact
About 3%-6% of children infected with Hib will not survive. Of those who do survive, many are left with long-term outcomes, including paralysis, deafness or blindness. Survivors can also have lifelong neurologic conditions, including developmental delay, seizure disorders and learning disabilities.
Infection control: Reducing the spread of Hib
Hib spreads between people with close contact through respiratory secretions after someone coughs or sneezes. It also spreads through direct contact with infected secretions, such as from sharing a glass or utensils, or kissing.
While someone is sick, other patients around that child in a healthcare setting, such as those in the waiting room, are not at risk. Healthcare workers, however, can be in close contact with secretions through bedside care and procedures like intubation and need to wear personal protective equipment, including masks.
Unvaccinated household contacts and children younger than 4 years of age are at the highest risk of infection after contact with someone who is sick from Hib. For this reason, select groups of people are recommended to receive a course of the antibiotic rifampin, after their close contact.
Household contacts should receive antibiotics in the following circumstances:
- Household has at least one child younger than 4 years of age who is unvaccinated or who has not received all recommended doses.
- Household has a child younger than 12 months who has not completed the primary Hib series (two or three doses by 6 months of age, depending on brand).
- Household has an immune-compromised child, regardless of their vaccination history.
If the infected patient attends a setting with high numbers of unvaccinated individuals (e.g., preschool and childcare centers), the facility should work with public health authorities to determine the need for antibiotics among their population.
Haemophilus influenzae type b: Key clinical takeaways
Hib remains uncommon, with fewer than 50 cases occurring each year in the U.S. However, if vaccination rates decrease, more children will be at risk for this deadly infection. Providers should be prepared to recognize its many presentations and act fast.
Resources for families
- Haemophilus Influenzae Type B (Hib): The Disease & Vaccines (webpage)
- Doctors Talk Meningitis (video)
- Vaccines on the Go: What You Should Know (mobile app)
Resources for providers
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 Haemophilus influenzae type b (Hib). With more families refusing or delaying routine vaccinations, healthcare providers are more frequently faced with the need to evaluate and manage unvaccinated children in their practice. One of the more common questions our infectious disease colleagues are asked is, “Should I be worried about something like meningitis in this unvaccinated child?”.
Prior to availability of the Hib vaccine, about 20,000 cases of invasive Hib disease occurred each year in the U.S. This plummeted by 99% with widespread use of the vaccine. The Hib vaccine not only reduced the risk of disease, but it also reduced colonization in the throat, decreasing spread in the community as well as cases among unvaccinated people. Importantly, vaccination rates need to remain above approximately 90% in infants and toddlers — the groups that drive transmission — to maintain these community benefits, more commonly referred to as herd immunity.
Recognizing Hib
Children with Hib infections can have an array of symptoms. Most feared is meningitis (swelling of the brain). Children with meningitis have classic symptoms like fever, irritability, lack of appetite, stiff neck and drowsiness. Infants may have a bulging fontanelle. Symptoms can progress to coma and death.
But Hib doesn’t just cause meningitis. It can also cause:
- Sepsis (bloodstream infections)
- Pneumonia (infection of the lungs)
- Cellulitis (infection of the skin; for Hib, a common location involves the side of the cheek)
- Arthritis (infection of the joints)
- Epiglottitis (infection and swelling of the tissue above the airway)
Hib, therefore, needs to be considered as a cause of any of these syndromes in unvaccinated children.
Making a Hib diagnosis
Depending on the patient’s syndrome, different tests may be required. If evaluating for meningitis, a lumbar puncture is needed for a gram stain (looking for small gram-negative coccobacilli), white blood cell count, measurements of protein (which will be high) and glucose (which will be low). Many multiplex PCR panels for meningitis include testing for Hib; alternatively, the diagnosis can be confirmed through culturing spinal fluid.
Clinicians continue to routinely see syndromes such as sepsis, pneumonia, cellulitis and arthritis caused by many types of viruses and bacteria. While the evaluation of an unvaccinated child does not need to change for these conditions, clinicians should consider Hib as a cause of these illnesses in unvaccinated children as this will impact the choice of antibiotic for treatment.
Treatment & management of Hib
Antibiotics are the primary method of treatment for Hib. Clinicians should recognize that empiric antibiotics, the antibiotics administered when a culture isn’t taken or available yet, need to cover Hib in unvaccinated children. In the cases where a culture is not obtained, the child’s immunization status may be a major driver in determining the plan for antibiotics. Clinical guidelines in the vaccine era highlight the need to consider a patient’s vaccination status when making empiric treatment decisions. For example, first line treatment for community-acquired pneumonia in children is amoxicillin, but many strains of Hib will not respond to this antibiotic, instead requiring a broader antibiotic like amoxicillin-clavulanic acid. This can be used for other infections, like sinusitis or ear infections, where Hib can cause infection.
Depending on the patient’s illness, the supportive care required until antibiotics take effect can vary greatly. For example, some children with pneumonia may be treated at home; others may need admission for oxygen — or worse, intubation. In contrast, sepsis, meningitis and epiglottitis are all medical emergencies and universally should be treated emergently in the hospital setting with intravenous antibiotics while waiting for results of initial testing. Third-generation cephalosporins, such as ceftriaxone, are commonly used in the emergency room or hospital for serious infections, like meningitis, bloodstream infections or epiglottitis. Despite early antibiotic treatment, not all infections are survivable.
Long-term impact
About 3%-6% of children infected with Hib will not survive. Of those who do survive, many are left with long-term outcomes, including paralysis, deafness or blindness. Survivors can also have lifelong neurologic conditions, including developmental delay, seizure disorders and learning disabilities.
Infection control: Reducing the spread of Hib
Hib spreads between people with close contact through respiratory secretions after someone coughs or sneezes. It also spreads through direct contact with infected secretions, such as from sharing a glass or utensils, or kissing.
While someone is sick, other patients around that child in a healthcare setting, such as those in the waiting room, are not at risk. Healthcare workers, however, can be in close contact with secretions through bedside care and procedures like intubation and need to wear personal protective equipment, including masks.
Unvaccinated household contacts and children younger than 4 years of age are at the highest risk of infection after contact with someone who is sick from Hib. For this reason, select groups of people are recommended to receive a course of the antibiotic rifampin, after their close contact.
Household contacts should receive antibiotics in the following circumstances:
- Household has at least one child younger than 4 years of age who is unvaccinated or who has not received all recommended doses.
- Household has a child younger than 12 months who has not completed the primary Hib series (two or three doses by 6 months of age, depending on brand).
- Household has an immune-compromised child, regardless of their vaccination history.
If the infected patient attends a setting with high numbers of unvaccinated individuals (e.g., preschool and childcare centers), the facility should work with public health authorities to determine the need for antibiotics among their population.
Haemophilus influenzae type b: Key clinical takeaways
Hib remains uncommon, with fewer than 50 cases occurring each year in the U.S. However, if vaccination rates decrease, more children will be at risk for this deadly infection. Providers should be prepared to recognize its many presentations and act fast.
Resources for families
- Haemophilus Influenzae Type B (Hib): The Disease & Vaccines (webpage)
- Doctors Talk Meningitis (video)
- Vaccines on the Go: What You Should Know (mobile app)
Resources for providers
Contributed by: Lori Handy, MD, MSCE , Charlotte A. Moser, MS, Paul A. Offit, MD