Special Risk Groups - New Zealand Immunisation Schedule

Immunisation
Special Risk Groups

Note: The following is an extract from page 67 of the Immunisation Handbook 2006.

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Special risk groups: medical conditions

Some conditions increase the risk from infectious diseases, and children with such conditions should be immunised as a matter of priority. These conditions include chronic diseases, and immune defi cient and immune compromised individuals. Special care is required with some live vaccines. When considering immunising children at risk, seek advice from the child’s paediatrician.

Preterm infants

Preterm infants and other infants with low birthweight should be immunised at the usual chronological age with the usual vaccine dosage.

If an infant is still in hospital when immunisations are due, the DTaP-IPV and Hib- Hepatitis B vaccines should be given at the scheduled chronological age. Babies who weigh under 2 kg have a sub-optimal response to hepatitis B vaccine, so immunisation may need to be deferred (see section 3.5). In New Zealand, some neonatal units give Hib-Hepatitis B at six weeks of age (chronological age); others when the baby weighs 2 kg. However, all pre-term infants born to HBsAg positive mothers should receive immune prophylaxis (HBIG and hepatitis B vaccine) as soon as possible after birth. Available data suggests very low birthweight infants have a less adequate antibody response to Hib-OMP vaccine and an extra dose is recommended at age fi ve months, (see chapter 7). The response may be decreased in chronically sick infants.

Preterm infants who develop chronic respiratory disease should be given influenza vaccine at six months of age, and a second dose one month later (influenza vaccine is usually available from March to June each year). Further protection of infants with these and other chronic conditions should be ensured by immunising the family and caregivers, including hospital personnel.

Immune deficient children

For information on the pneumococcal immunisation programme for high risk children, see chapter 16: Pneumococcal Disease.

Diagnosis of immune deficient children is often not made before children start their immunisation schedules. However, no live virus vaccines are given in the fi rst year of life. For children with immune suppression, consult their specialist about a suitable immunisation schedule.

The safety and effectiveness of vaccines in people with immune defi ciency are determined by the nature and degree of immune suppression. Immune defi ciency conditions may be divided into primary and secondary. Primary immune deficiencies that present in childhood are generally inherited, and include antibody defi ciency (disorders of B lymphocytes or antibody production), defects of cell mediated immunity (disorders of T lymphocytes, which most often present as combined defects affecting antibody production as well), and defects of complement and phagocytic function. Secondary disorders of the immune system are acquired, and occur in people with human immunodefi ciency virus (HIV), malignant neoplasms or transplantation, and in people receiving immune suppressive treatment or radiotherapy (see Table 1.9).

Experience with vaccine administration in immune suppressed children is limited.

Live vaccines
Live vaccines(these include MMR, varicella and BCG) should not in general be given to people who are severely immune suppressed, either viral or bacterial, because of the risk of disease from vaccine strains.

Inactivated vaccines
Inactivated vaccines (IPV, DTaP, hepatitis B, Hib, pneumococcal and infl uenza) may be administered since the risk of adverse reactions is not increased in immune suppressed children. However, the response of immune suppressed children to these inactivated vaccines may be inadequate. In children with a secondary immune deficiency, their ability to develop an adequate immunological response depends on when immune suppression occurs. In children in whom immune suppressive therapy is discontinued, an adequate response usually occurs between three months and one year after discontinuation. Infl uenza vaccine should be given to immune suppressed children before each infl uenza season, and to children receiving chemotherapy for malignant neoplasm three to four weeks after chemotherapy is discontinued, when both the peripheral granulocyte and lymphocyte counts are > 1.0 x 109/L.

Primary immune deficiencies
Live vaccines are contraindicated for most children with B lymphocyte defects (except IgA deficiency), and for all children with T lymphocyte mediated disorders of immune function. Most of these children will be on intravenous immunogobulin (IVIG) replacement therapy, which provides passive protection against most vaccine preventable infections. Seek specialist paediatric advice. (See Table 1.9.)

Secondary (acquired) immune deficiencies
Factors to consider when immunising children with secondary immune deficiency include the underlying disease, the dose and schedule of the immune suppressive drugs, the infectious disease, and the immunisation history of the child. Live vaccines, generally, are contraindicated because of the risk of serious adverse effects. Exceptions are children with HIV infection who are not severely immune compromised, in whom MMR is recommended. Varicella vaccine is recommended for children with HIV infection with CD4+ T lymphocyte values of 25 percent or greater. Live virus vaccines should be withheld until at least three months after cessation of immune suppressive cancer chemotherapy, and tests of immune function may be used to guide safe timing. Recommendations for children on corticosteroids are given below. Seek specialist paediatric advice.

Other considerations
Children with a primary or secondary immune defi ciency may not respond adequately to an immunising agent. Specific serum antibody titres should be determined to guide future management of exposures and vaccine. People with certain immune deficiencies may benefit from specific vaccines to prevent diseases to which they are particularly susceptible. Pneumococcal and meningococcal vaccine are indicated to those with splenic dysfunction, asplenia and complement deficiencies, who are at increased risk of infection from encapsulated bacteria. Influenza vaccine is indicated for children with splenic dysfunction, asplenia, and phagocyte function defi ciencies to prevent influenza and reduce risk of secondary bacterial infections.

Household contacts
Immunologically competent siblings and household contacts may receive all the National Immunisation Schedule vaccines, particularly IPV and MMR. There is no risk of transmission of the IPV or MMR vaccine viruses to the immune compromised individual. However, it is important to ensure that close household contacts are immune for the added protection of the immune suppressed individual. Varicella vaccine can be given safely to household contacts of immune suppressed children.

Oral polio vaccine, which was contraindicated in households where immune suppressed individuals lived, is no longer available in New Zealand.

A summary of the appropriate immunisation for children with primary and secondary immune deficiencies is given in Table 1.9.

Table 1.9: Immunisation of children with primary and secondary immune deficiencies

Category	Specific immune deficiency	Vaccine contraindications	Efficacy and comments
Primary
B lymphocyte (humoral)	X-linked and common variable immune deficiency	Live bacterial vaccines, MMR and varicella	The efficacy of any vaccine dependent on humoral response is doubtful; IVIG interferes with the response to live vaccines and provides passive protection.
B lymphocyte (humoral)	Selective IgA deficiency	Nil	All vaccines are probably effective
T lymphocyte (cell mediated and humoral)	Severe combined immune deficiency	All live vaccines^a,b	The efficacy of any vaccine dependent on humoral or cellular response is doubtful.
Complement	Deficiency of early components (C1, C4, C2, C3)	None	All routine vaccines are probably effective; pneumococcal and meningococcal are recommended.
Complement	Deficiency of late components (C5–9), properdin, factor B	None	All routine vaccines are probably effective; meningococcal vaccine is recommended.
Phagocytic function	Chronic granulomatous disease, leukocyte adhesion defect, myeloperoxidase deficiency	Live bacterial vaccines^b	All routine vaccines are probably effective; consider influenza vaccine.
Secondary
	HIV/AIDS	BCG; withhold MMR and varicella in severely immunocompromised children	MMR, varicella and all inactivated vaccines may be effective.^c
	Malignant neoplasm, transplantation, immune suppressive or radiation therapy	Live viral and bacterial, depending on immune statusa,^b	The effectiveness of any vaccine depends on the degree of immune suppression.

Key: IVIG: intravenous immunoglobulin; IgA: immunoglobulin A; HIV: human immunodeficiency virus; AIDS: acquired immunodeficiency syndrome; BCG: Bacille Calmette-Guérin; MMR: measles, mumps and rubella.

Live viral vaccines (MMR, varicella).
Live bacterial vaccines (BCG).
HIV infected children should receive IG after exposure to measles and may receive varicella vaccine if CD4+ count ≥25 percent.

Children receiving corticosteroids
Children who receive corticosteroid therapy can become immune suppressed. The minimal amount of corticosteroid and duration of administration suffi cient to cause immune suppression is not well defined, and is dependent on dose, duration and underlying disease. Many clinicians consider a daily dosage equivalent to 2 mg/kg prednisone or greater, or a total daily dosage of 20 mg or greater, particularly when given for 14 days or more, is suffi cient to raise concern about the safety of live virus vaccines.

This guide may be used for safe live virus vaccine administration to children on corticosteroids.

Topical therapy or local injections of corticosteroids, including on skin or respiratory tract (by aerosol) or intra-articular, bursal or tendon injections, usually do not result in immune suppression, and live virus vaccines may be given after topical therapy.
Children on maintenance physiologic doses of corticosteroids can receive live virus vaccine while on treatment.
Children on low to moderate doses of systemic steroids given daily or on alternate days can receive live virus vaccines. This includes children receiving less than 2 mg/kg per day prednisone or less than 20 mg/day if they weigh more than 10 kg, or an equivalent dose of another short acting systemic corticosteroid.
Children receiving high dose corticosteroids daily or on alternate days for fewer than 14 days (eg, children receiving 2 mg/kg of prednisone, or up to 20 mg if the child weighs more than 10 kg) can receive live virus vaccines immediately on discontinuation of treatment. Some experts would delay immunisation for two weeks if possible.
Children receiving high dose corticosteroids daily or on alternate days for more than 14 days (eg, children receiving 2 mg/kg of prednisone, or 20 mg or more if the child weighs more than 10 kg) should not receive live virus vaccines until the corticosteroid therapy has been discontinued for at least one month.
Children who have a disease process which causes immune suppression, and who are being treated with either systemic or locally administered corticosteroids, should not be offered live virus vaccines except in special circumstances.

Note: these guidelines are made to ensure safety of administration of the live virus vaccine and may not achieve optimal vaccine immunogenicity.

Hodgkin’s disease

Patients suffering from Hodgkin’s disease should be immunised with Hib and pneumococcal vaccines (see chapters 7 and 16) according to age specifi c recommendations, and have their routine childhood vaccines and MeNZB™ updated as required. Quadrivalent meningococcal vaccine should also be considered. The antibody response is best if immunisation is undertaken 10–14 days prior to the initiation of any chemotherapy. If given during chemotherapy or shortly after its cessation, the antibody response will be sub-optimal. The immune system recovers quickly and immunisation can be carried out three months after chemotherapy ceases. For children who received immunisation during therapy, the vaccines should be re-administered three months after discontinuation of therapy.

Children and adults receiving chemotherapy or immune suppressive therapy

Live virus vaccines (see chapters 9–11 and 17) are generally contraindicated
because of the risk of serious adverse effects. An exception appears to be the judicious use of live varicella vaccine in children with acute lymphocytic leukaemia in continuous remission of at least one year, whose total lymphocyte count is > 0.7 × 109/L and in whom the risk of natural varicella far outweighs the risk from attenuated vaccine virus. Inactivated vaccines may be used where appropriate, but the immune response is likely to be sub optimal and following exposure passive immunisation with IG is likely to be required.

After cessation of immune suppressive therapy, live virus vaccines are generally withheld for an interval of not less than three months. The interval may need to be extended according to the intensity and type of the immune suppressive therapy, radiation therapy, underlying disease and other factors.

Bone marrow transplant

Many factors can affect transplant recipients’ immunity to vaccine preventable diseases following a successful marrow transplant. These include the donor’s immunity, the type of transplant, the interval since the transplant, the continuing use of immune suppressive drugs, and graft versus host disease (GVHD). Some recipients acquire the immunity of the donor, but others lose all serological evidence of immunity. Serological tests should be carried out to establish immunological status 12 months after bone marrow transplant and prior to immunisation. If tests are not available, the patient should be reimmunised according to the appropriate catch-up schedule (see Appendix 2).

One study suggests that three doses of tetanus toxoid are required after bone marrow transplant to achieve adequate immunity. Information regarding the response to diphtheria toxoid is not available, but at least three doses will be required. As noted above, the usual childhood immunisations should be given for under seven years of age, and after the seventh birthday Td should be given. No data is available about the other inactivated bacterial vaccines (pneumococcal, meningococcal or Hib), but for maximum benefi t all should be delayed for at least one year after transplant.

Healthy survivors of bone marrow transplant can be given MMR vaccine two years after transplant, but the vaccine should not be given to individuals suffering from GVHD, because of a risk of a resulting chronic latent virus infection leading to central nervous system sequelae.3 It is important to ensure that household contacts are immune to infectious diseases wherever possible. Household contacts may be safely given MMR (see chapter 9). IPV can be given to transplant recipients and their household contacts (see chapter 8).

Solid organ transplants

Children older than 12 months who have been scheduled for solid organ transplantation should receive the MMR vaccine at least one month before the transplant. Measles antibody titres should be measured one to two years after the transplant; immunisation may be repeated if titres are low. It may be advisable to check other antibody titres and reimmunise where indicated. The use of passive immunisation with IG should be based on the documentation of negative antibody titres and a positive history of exposure to the disease. See chapter 16 for further information regarding pneumococcal immunisation for these children.

HIV infection

For children with HIV infection, discuss with their specialist the recommendations for immunisation. HIV positive children (CD4+ > 14 percent), whether symptomatic or asymptomatic, should follow the routine immunisation schedule, including MMR. No ill effects have been reported following administration of MMR vaccines to HIV positive individuals, who are at increased risk from these three diseases.

The efficacy of any vaccine may be reduced in HIV positive individuals. Serological testing and the need for additional doses should be discussed with the child’s specialist.

Passive immunisation with IG should be considered in HIV positive individuals exposed to measles, even if they have received measles immunisation (see section 9.8). Zoster immunoglobulin (ZIG) should be offered to HIV positive individuals who have not been infected with clinical chickenpox or who can be shown to be nonimmune following exposure to chickenpox or shingles. ZIG should be given within 72 hours of exposure but may still have some effects up to seven days later (see section 17.8). For information on varicella vaccine see chapter 17. In general varicella vaccine may be safely given to children at CDC A1 or N1 ie, CD4+ ≥ 25 percent.

Since influenza has not caused excessive morbidity in HIV infected individuals, this vaccine is not routinely recommended for HIV positive individuals.

For other vaccines, see specifi c disease chapters (chapter 15 for meningococcal invasive disease, chapter 16 for pneumococcal disease).

Asplenic children

There are three general reasons why individuals may not have a functioning spleen:

surgical removal (eg, post trauma)
disease (eg, sickle cell disease, thalassaemia)
congenital asplenia.

All asplenic individuals are at increased risk of fulminant bacteraemia, which is associated with a high mortality rate. The risk is greatest for infants, and probably declines with age and with the number of years since onset of asplenia. The degree of risk of mortality from sepsis is also infl uenced by the nature of the underlying disease, being increased 50 times (compared with healthy children) in asplenia after trauma, 350 times in asplenia with sickle cell disease, and even higher in asplenia with thalassaemia.

The organisms that most commonly cause fulminant sepsis in these individuals are Streptococcus pneumoniae (most frequent), N. meningitidis, H. infl uenzae type b,
and Escherichia coli. Less commonly, infection may be caused by other streptococci, Staphylococcus aureus and gram-negative coliforms (eg, Klebsiella, Salmonella
sp and Pseudomonas aeruginosa). There is an increased fatality from malaria for asplenic individuals.

If possible, splenectomy should be avoided or delayed, accessory spleens should be preserved, hemisplenectomy should be performed during staging for Hodgkin’s disease, and partial splenectomy should be performed for benign splenic tumours.

The following vaccines are recommended in addition to the normal National Immunisation Schedule:

pneumococcal vaccine – for recommendations for pneumococcal conjugate vaccine (PCV 7) and polysaccharide pneumococcal vaccine (23 PPV) for all asplenic children and adults see also below, and chapter 16.
quadrivalent meningococcal polysaccharide vaccine for all asplenic children two years of age or older (see chapter 15 for adult recommendations); conjugate meningococcal group C vaccine may be given to children under two years of age.

Because of an increased risk of infection it is particularly important that asplenic children, whatever their age, receive the Hib vaccine schedule as per the National Immunisation Schedule.

Pneumococcal vaccine appears to reduce the risk of fulminant pneumococcal bacteraemia in asplenic children. The effi cacy of other bacterial vaccines (eg, Hib) in these circumstances is not clearly established, but they are probably as effective as pneumococcal vaccine.

Antimicrobial prophylaxis
The effectiveness of antimicrobial prophylaxis in asplenic children was proven only for sickle cell disease, but should be strongly considered for all children under five years of age and for at least one year after splenectomy. Monthly benzathine penicillin injections have been shown to reduce episodes of pneumococcal bacteraemia in asplenic children as compared with rates observed in untreated children. Oral penicillin daily also reduces the incidence of severe bacterial infection by 84 percent in asplenic children, compared with rates observed in placebo treated controls.

It is reasonable to extrapolate these data to other asplenic children with a high risk of bacteraemia (eg, asplenic children with malignancies, thalassaemia, etc). There is less agreement regarding the use of chemoprophylaxis in children who have been splenectomised following trauma.

Chemoprophylaxis should be recommended for:

asplenic children fi ve years of age and under
for older asplenic children at least two years post-splenectomy.

There are no studies that help decide the age at which chemoprophylaxis should be discontinued. This decision has to be made according to clinical judgement.

The dosage given is as follows:

under five years of age: 125 mg bd oral penicillin
fi ve years of age and older: 250 mg bd oral penicillin.

An alternative recommended by some experts is amoxycillin 20 mg/kg per day.

Parents/caregivers should be advised that all febrile illnesses are potentially serious and that they should seek immediate medical help in these circumstances. Patients should be hospitalised if bacteraemia is a possibility. In hospital, the usual treatment would be cefotaxime, ceftriaxone, or another regimen effective against S. pneumoniae, H. influenzae type b and N. meningitis.

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Page last updated: 13 June 2008