| Haemophilus influenzae type b (Hib) |
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| Disease Issues |
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| What is
Haemophilus influenzae? |
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| 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. |
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| 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. |
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| How common is
Haemophilus influenzae type b (Hib) disease? |
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| 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. |
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| 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. Since 2000, 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. |
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| Only 30 cases of
invasive Hib disease among children younger
than 5 years were reported in 2016. 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. |
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| What are the
risk factors for invasive Hib disease? |
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| 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. |
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| What's the
difference between Haemophilus influenzae type
b and influenza? |
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| 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. |
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| 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. |
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| Where can I
find the most recent recommendations for Hib
vaccines? |
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| 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. |
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| What Hib
vaccines are available in the United States? |
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| As of September
2018 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). |
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| One combination
vaccine containing Hib is currently available
in the United States. Pentacel (Sanofi
Pasteur) contains Hib conjugate, DTaP and
inactivated polio vaccines and 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. |
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| What are the
recommendations for Hib vaccination in the
United States? |
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| 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, or Pentacel 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. |
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| 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. |
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| Can all of the
licensed Hib-containing vaccines be used
interchangeably? |
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| Yes. If either
ActHIB or Hiberix is used for a routine
primary series dose, a complete routine
primary series consists of three doses. |
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| What is the
Hib vaccine schedule for children who have
fallen behind or are completely unvaccinated? |
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| 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. |
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| If a healthy infant
received one dose of Hib at 5 months, and
another at 15 months, does he/she need any
more doses? |
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| No. 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. |
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| 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? |
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| 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. |
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| A 4-year-old
received dose #3 of Hib at age 6 months. Does
the child need dose #4? |
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| 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. |
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| I've just
evaluated a 7-year old who does not have a
record of receiving Hib vaccine. Would a dose
be indicated now? |
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| 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. |
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| If a dose of
Hib vaccine was given by mistake to a
2-week-old, should further doses of Hib
vaccine be given? |
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| 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. |
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| Which adults
should receive Hib vaccine? |
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| 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
vaccine should be administered 14 or more days
before splenectomy if possible. Recipients of
a hematopoietic stem cell transplant should be
vaccinated with a 3-dose series of Hib vaccine
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. |
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| When should
Hib vaccine be administered to a person having
a splenectomy? |
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| 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. |
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| 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? |
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| 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. |
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| 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? |
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| 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. |
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| Should
children who recover from invasive Hib disease
be vaccinated? |
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| 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 child’s age should be
administered. |
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| Are there any
special Hib vaccination recommendations for
American Indian/Alaska Native (AI/AN)
children? |
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| 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. |
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| How should Hib
vaccines be administered? |
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| All Hib-containing
vaccines should be administered by the
intramuscular route. |
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| 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? |
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| 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. |
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| What are the
contraindications and precautions for Hib
vaccine? |
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| 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. The PedvaxHIB vial
stopper contains dry natural rubber which
could produce an allergic reaction in children
with severe allergy to latex. 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 are the
same as those for its individual component
vaccines (that is, DTaP, Hib, and IPV). |
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| What adverse
reactions may occur after Hib vaccination? |
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| 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. |
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| 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/). |
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| How should Hib
vaccines be stored? |
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| Hib vaccine
should be maintained at refrigerator
temperature between 2°C and 8°C (36°F and
46°F). 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 CDC’s Vaccine
Storage and
Handling Toolkit at
www.cdc.gov/vaccines/hcp/admin/storage/toolkit/storage-handling-toolkit.pdf. |
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| Should close
contacts of a patient with invasive Hib
disease receive antibiotic prophylaxis? |
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| 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. |
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| 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. |
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| Rifampin
chemoprophylaxis is recommended for all
household contacts in households with members
younger than 4 years who are not fully
vaccinated, households with a child younger
than 12 moths who has not completed the
primary Hib series, or households with a
contact who is an immunocompromised child
regardless of that child's vaccination status. |
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| 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 2018 AAP Red
Book, pages 369–1 for more information on this
issue. |
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| 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. |
ACIP Recommendations
Vaccine Information Statements 
