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Haemophilus influenzae type b (Hib)

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Haemophilus influenzae type b (Hib)

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Haemophilus influenzae type b (Hib)
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Disease Issues
What is Haemophilus influenzae?
Haemophilus influenzae is a bacteria that has encapsulated (typeable) or unencapsulated (nontypeable) strains. Encapsulated strains express one of six antigenically capsular polysaccharides (types a, b, c, d, e, or f). Historically, type b (Hib) is the most common type to cause invasive disease particularly in young children. H. influenzae colonizes the upper respiratory tract of humans and is transmitted person-to-person by inhalation of respiratory droplets or by direct contact with respiratory tract secretions.
Encapsulated H. influenzae nontype b strains, particularly type a, can cause invasive disease similar to Hib disease (see next question). Nontypeable strains also can cause invasive disease but more commonly cause mucosal infections such as otitis media, conjunctivitis, and sinusitis. Vaccines are only available for H. influenzae type b; Hib vaccines only protect against H. influenzae type b strains.
How common is Haemophilus influenzae type b (Hib) disease?
Before 1985, Hib was the leading cause of bacterial meningitis and a common cause of other invasive diseases (such as epiglottitis, pneumonia, septic arthritis, cellulitis, purulent pericarditis, and bacteremia) among U.S. children younger than 5 years of age. An estimated 20,000 cases of invasive Hib disease occurred in this age group each year. Meningitis occurred in approximately two thirds of children with invasive Hib disease; 15%–30% of survivors had hearing impairment or severe permanent neurologic sequelae. Approximately 4% of all cases were fatal.
Following the licensure of conjugate Hib vaccines in 1987 and 1989, the incidence of Hib disease fell dramatically. During 1989–2000, the annual incidence of invasive Hib disease among children younger than 5 years of age decreased by 99%, to less than one case per 100,000 children. During 2000Ė2012, the average annual incidence rate of invasive Hib disease among children younger than 5 years of age in the United States remained below the Healthy People 2020 goal of 0.27/100,000 children.
Only 40 cases of invasive Hib disease among children younger than 5 years were reported in 2014. The majority of Hib disease in the United States occurs among unimmunized and underimmunized infants and children (those who have an incomplete primary series or are lacking a booster dose) and among infants too young to have completed the primary immunization series.
What are the risk factors for invasive Hib disease?
Persons with certain immunocompromising conditions are considered at increased risk for invasive Hib disease. These conditions include functional or anatomic asplenia, HIV infection, immunoglobulin deficiency including immunoglobulin G2 subclass deficiency, early component complement deficiency, receipt of a hematopoietic stem cell transplant, or receipt of chemotherapy or radiation therapy for treatment of cancer.
What's the difference between Haemophilus influenzae type b and influenza?
Haemophilus influenzae type b is a polysaccharide-encapsulated bacteria that causes a variety of invasive diseases, such as meningitis, epiglottitis, and pneumonia. Influenza is a virus that causes the disease influenza.
Historical note: Haemophilus influenzae was first isolated in 1889 from the sputum of a patient who died of influenza, and the isolated organism (then called the Pfeiffer bacillus) was assumed to have caused the patient's illness. Haemophilus influenzae received its name in 1920, to acknowledge its historical association with influenza. The viral cause of influenza was not discovered until 1933.
Vaccine Recommendations Back to top
Where can I find the most recent recommendations for Hib vaccines?
The most recent Advisory Committee on Immunization Practices (ACIP) recommendations for Hib vaccination were published in 2014 and are available on the CDC website at www.cdc.gov/mmwr/pdf/rr/rr6301.pdf. Guidance for Hib vaccination is also provided in the annual childhood immunization schedule, available at www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html.
What Hib vaccines are available in the United States?
As of January 2016 three monovalent Hib vaccines are available in the United States: PedvaxHIB (Merck), ActHIB (Sanofi Pasteur) and Hiberix (GlaxoSmithKline). These vaccines are composed of Hib capsular polysaccharide chemically bound (conjugated) to a protein. All thee vaccines are approved for infants in a 3 or 4 dose series (depending on brand).
Two combination vaccines containing Hib are currently available in the United States. Pentacel (Sanofi Pasteur) contains Hib conjugate, DTaP and inactivated polio vaccines. It is approved for infants at age 2, 4, 6, and 15 through 18 months of age. It is not approved for the DTaP/IPV booster dose at age 4 through 6 years. MenHibRix (GlaxoSmithKline) contains Hib conjugate and Neisseria meningitidis serogroups C and Y conjugate vaccines. It is approved for infants at ages 2, 4, 6, and 12 through 15 months.
What are the recommendations for Hib vaccination in the United States?
The ACIP recommends routine administration of a conjugate Hib vaccine series for all infants beginning at age 2 months. Infants 2 through 6 months of age should receive a 3-dose series of ActHIB, Hiberix, Pentacel, or MenHibRix or a 2-dose series of PedvaxHIB. The first dose can be administered as early as age 6 weeks. Hib-containing vaccine should not be given before 6 weeks of age. Doses given before 12 months of age should be separated by at least 4 weeks. A booster dose (which will be dose 3 or 4 depending on vaccine type used in primary series) of any Hib-containing vaccine is recommended at age 12 through 15 months and at least 8 weeks after the most recent Hib dose.
Medically stable preterm infants should be vaccinated beginning at age 2 months according to the schedule recommended for other infants, on the basis of chronological age. Unimmunized children 60 months and older who have HIV infection should receive 1 dose of Hib vaccine.
Can all of the licensed Hib-containing vaccines be used interchangeably?
Yes. If either ActHIB or Hiberix is used for a routine primary series dose, a complete routine primary series consists of three doses.
Scheduling and Administering Vaccine Back to top
What is the Hib vaccine schedule for children who have fallen behind or are completely unvaccinated?
Healthcare providers should refer to the catch-up schedule which is approved and published each year by the ACIP, AAP, and AAFP (available at www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html). The catch-up schedule will help determine the number of additional doses needed and the minimum intervals between doses. However, if a healthy child receives a dose of Hib vaccine at 15 months of age or older, he or she does not need any further doses regardless of the number of doses received before 15 months of age. Some high-risk children between the ages of 15 months and 59 months will be recommended for two doses of Hib vaccine based on previous history of incomplete vaccination.
If an infant received one dose of Hib at 5 months, and another at 15 months, does he/she need any more doses?
No. If a child receives a dose of Hib vaccine at 15 months of age or older, he or she does not need any further doses regardless of the number of doses received before 15 months of age.
Since the booster dose of Hib vaccine can be given at 12–15 months, is it still necessary to "boost" two months later if the first dose was given at 12–14 months?
If the child received a primary series (2 or 3 doses) of Hib vaccine in the first year of life, then the final (booster) dose of the series may be given as early as 12 months, provided at least 2 months have passed since the last dose. An unvaccinated 12–14 month old child should receive one dose as a primary series, and a booster dose 2 months later. Unvaccinated healthy children 15–59 months of age need only a single dose of any licensed conjugate Hib vaccine. Some high-risk children 15–59 months of age are recommended for two doses of Hib vaccine based on previous history of incomplete vaccination.
A 4-year-old received dose #3 of Hib at age 6 months. Does the child need dose #4?
Yes. All children less than 5 years old need at least one dose of Hib vaccine on or after the first birthday. The last dose should be separated from the previous dose by at least 8 weeks.
I've just evaluated a 7-year old who does not have a record of receiving Hib vaccine. Would a dose be indicated now?
ACIP does not recommend routine Hib vaccination of healthy children 59 months of age or older, even if they have no prior history of Hib vaccination.
If a dose of Hib vaccine was given by mistake to a 2-week-old, should further doses of Hib vaccine be given?
Limited data suggest that Hib vaccine given before 6 weeks of age may induce immunologic tolerance to Hib antigen and reduce the response to subsequent doses. As a result, Hib vaccine should not be given earlier than 6 weeks of age. However, if a dose was administered before 6 weeks of age, it should not be counted as part of the Hib series. A full series of 3 or 4 doses, depending on the product used, should be started at 2 months of age as usual. No special protocol or testing is recommended for children who received a dose of Hib vaccine before 6 weeks of age.
Which adults should receive Hib vaccine?
Hib vaccine is not routinely recommended for healthy adults 19 years and older, even if the person did not receive Hib vaccine as a child. However, ACIP recommends that one dose of Hib vaccine should be administered to persons who have anatomical or functional asplenia or sickle cell disease or are undergoing elective splenectomy if they have not previously received Hib vaccine. Hib vaccination 14 or more days before splenectomy is suggested. Recipients of a hematopoietic stem cell transplant should be vaccinated with a 3-dose regimen 6 to 12 months after a successful transplant, regardless of vaccination history; at least 4 weeks should separate doses. Hib vaccine is not recommended for adults with HIV infection since their risk for Hib disease is low.
When should Hib vaccine be administered to a person having a splenectomy?
When elective splenectomy is planned, vaccination with pneumococcal, meningococcal, and Hib vaccines should precede surgery by at least 2 weeks, if possible. If vaccines are not administered before surgery, they should be administered as soon as the person's condition stabilizes after surgery.
Should adult patients who are not asplenic but who have hypogammaglobulinemia receive Hib vaccine? The 2014 Hib ACIP statement includes immunoglobulin deficiency in its "high-risk groups" for Hib disease, but the recommendations seem to imply that Hib vaccine is not necessarily for adults with immunoglobulin deficiency whose spleen is intact. Am I interpreting ACIP correctly on this matter?
You are interpreting the recommendations correctly, and age is an important factor in this issue. The recommendation for Hib vaccination for asplenia applies to persons of all ages. The recommendation for Hib vaccination for immunoglobulin deficiency applies only to children 12 through 59 months of age.
If a child receives a different brands of Hib vaccine at 2 and 4 months of age should a dose also be given at 6 months of age?
Yes. If different brands of Hib vaccine are given at 2 and 4 months of age then the child should receive a third primary dose of either vaccine at 6 months of age. A 2-dose primary schedule (that is, doses at age 2 and 4 months) is only appropriate when both doses are PedvaxHIB.
Should children who recover from invasive Hib disease be vaccinated?
Hib invasive disease does not always result in development of protective antibody levels. Children younger than 24 months of age who develop invasive Hib disease should be considered susceptible and should receive Hib vaccine. Vaccination of these children should start as soon as possible during the convalescent phase of the illness. A complete series as recommended for the childís age should be administered.
Are there any special Hib vaccination recommendations for American Indian/Alaska Native (AI/AN) children?
Hib meningitis incidence peaks at a younger age (4–6 months) among AI/AN infants than among other U.S. infant populations (6–7 months). Vaccination with a 2 dose primary series of PedvaxHIB is preferred for AI/AN infants to provide early protection because this vaccine produces a protective antibody response after the first dose.
How should Hib vaccines be administered?
All Hib-containing vaccines should be administered by the intramuscular route.
We inadvertently gave a child only the DTaP-IPV component of Pentacel not realizing that this component was intended to reconstitute the Hib component. Does this count as a valid dose of DTaP and IPV? Can we mix the unused Hib component with sterile water and give it separately?
Use of DTaP-IPV solution as the diluent for the Hib component is specifically written both on the Pentacel box AND on the DTaP-IPV vial label. The DTaP-IPV component will count as valid doses of DTaP and IPV vaccines, but take measures to prevent this error in the future. You cannot mix the Hib component with sterile water. ActHIB must ONLY be reconstituted with either the DTaP-IPV solution supplied with Pentacel, or with a specific ActHIB saline diluent. If you have ActHIB but neither diluent, you must contact the manufacturer (Sanofi) and obtain ActHIB diluent.
Contraindications and Precautions Back to top
What are the contraindications and precautions for Hib vaccine?
Vaccination with Hib vaccine is contraindicated for persons known to have experienced a severe allergic reaction (anaphylaxis) to a vaccine component or following a prior dose. Some presentations of Hib vaccine may contain latex or dry natural rubber in the packaging. Vaccination should be delayed for children with moderate or severe acute illnesses. Minor illnesses, such as a mild upper respiratory infection) are not contraindications to vaccination. Hib conjugate vaccines are contraindicated for children younger than 6 weeks of age because of the potential for development of immunologic tolerance. Contraindications and precautions for the use of Pentacel and MenHibrix are the same as those for its individual component vaccines (that is, DTaP, Hib, IPV, hepatitis B and meningococcal conjugate).
Vaccine Safety Back to top
What adverse reactions may occur after Hib vaccination?
Adverse reactions following Hib conjugate vaccines are not common. Swelling, redness, or pain have been reported in 5%–30% of recipients and usually resolve within 12–24 hours. Systemic reactions such as fever and irritability are infrequent. Serious reactions are rare.
All serious adverse events that occur after receipt of any vaccine should be reported to the Vaccine Adverse Event Reporting System (VAERS) (http://vaers.hhs.gov/).
Storage and Handling Back to top
How should Hib vaccines be stored?
Hib vaccine should be maintained at refrigerator temperature between 35°F and 46°F (2°C and 8°C). Manufacturer package inserts contain additional information and can be found at www.immunize.org/packageinserts/. For complete information on best practices and recommendations please refer to CDCís Vaccine Storage and Handling Toolkit at www.cdc.gov/vaccines/recs/storage/toolkit/storage-handling-toolkit.pdf.
Chemoprophylaxis Back to top
Should close contacts of a patient with invasive Hib disease receive antibiotic prophylaxis?
Secondary cases of Hib disease (illness occurring within 60 days of contact with a patient) occur but are rare. Secondary attack rates are higher among household contacts younger than 48 months (2.1%), especially those younger than 12 months (6%) and younger than 24 months (3%). Data are conflicting on the risk for secondary illness among child care contacts, but it is thought to be lower than among household contacts. Rifampin is recommended for chemoprophylaxis because it achieves high concentrations in respiratory secretions and eradicates nasopharyngeal carriage in more than 95% of carriers.
Index patients who are treated with an antibiotic other than cefotaxime or ceftriaxone and are younger than 2 years of age should receive rifampin prior to hospital discharge. Because cefotaxime and ceftriaxone eradicate Hib colonization, prophylaxis is not needed for patients treated with either of these antibiotics.
Rifampin chemoprophylaxis is recommended for all household contacts in households with members younger than 4 years who are not fully vaccinated or members younger than 18 years who are immunocompromised, regardless of their vaccination status.
Rifampin chemoprophylaxis is recommended in child care settings when two or more cases of invasive Hib disease have occurred within 60 days and unimmunized or underimmunized children attend the facility. When prophylaxis is indicated, it should be prescribed for all attendees, regardless of age or vaccine status, and for child care providers. See the AAP Red Book, pages 370–2 for more information on this issue.
There are no guidelines for control measures around cases of invasive nontype b H. influenzae disease. Chemoprophylaxis is not recommended for contacts of persons with invasive disease caused by nontype b H. influenzae because cases of secondary transmission of disease have not been documented.
This page was updated on January 29, 2016.
This page was reviewed on January 21, 2016.
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