Immunization status of children with HIV: failure to protect a vulnerable population

Abstract

The Children's HIV Association (http://www.chiva.org.uk/health/guidelines/immunisation; accessed 22 September 2009) and the Department of Health (http://www.dh.gov.uk/en/Publichealth/Healthprotection/Immunisation/Greenbook; accessed 17 September 2009) strongly recommend that HIV-positive children should receive all routine childhood immunizations. Exceptions are Bacillus Calmette–Guérin (BCG), regardless of CD4 cell count, and measles, mumps and rubella (MMR), if the CD4 cell count is <15% of total lymphocytes. HIV-infected children are at an increased risk of vaccine-preventable diseases. While we acknowledge that some vaccines are less effective in severely immunocompromised children [1], even on highly active antiretroviral therapy (HAART), we believe that efforts should be made to ensure immunization according to published UK guidelines. The aim was to audit the immunization status of HIV-positive children in London. A standardized proforma was used to collect data from children/adolescents attending four paediatric HIV clinics in 2008 (three tertiary level and one secondary level). Data were collected on routine and nonroutine vaccines from clinical notes and supplemented with information from Parent-Held Child Healthcare Records (‘Red Book’) and Primary Care records. Vaccination details supplied by parents, however seldom, were taken into account. Data were collected on 75 children. Fifty-five per cent were UK-born. The median age was 11 years (range 11 months to 20 years). The median CD4 percentage was 26% (range 4–47%) and the median viral load was 185 HIV-1 RNA copies/mL (range 0–2.4 × 105 copies/mL). Although children attended specialist clinics, only 5% had complete documentation of immunization in the medical notes. ‘Complete’ vaccination was determined on the basis of UK guidelines and accounted for age, vaccination history, contraindications, birth country and age of moving to the UK. Figure 1 shows proportions of children fully immunized with primary and booster doses of routine vaccines. Overall, 63% (186 of 297) of primary immunizations and only 41% (61 of 149) of booster immunizations were complete in children eligible to receive the vaccine (P<0.001). Sixty-one per cent (162 of 267) of all immunizations were complete in UK-born children compared with 47% (85 of 179) in non-UK-born children (P=0.006). Proportion of children fully immunized with routine vaccines. Nonroutine vaccinations in the UK include Bacillus Calmette–Guérin (BCG) for tuberculosis and hepatitis B. DTP, diphtheria, tetanus and pertussis; Hib, Haemophilus influenzae type b; Men C, meningococcal group C; MMR, measles, mumps and rubella; PCV, pneumococcal conjugate vaccine. Even though rates of immunization in London are lower than in the UK overall [e.g. 83% vs. 93% completed primary diphtheria, tetanus and pertussis (DTP) by age 5 years (http://www.ic.nhs.uk/statistics-and-data-collections/health-and-lifestyles/immunisation; accessed 3 September 2009)], rates in HIV-infected children were surprisingly low. HIV-infected children may have other risk factors for incomplete immunization such as residence in disadvantaged areas, history of hospital admission [2] or coming from an immigrant family. Childhood vaccinations are free; however, specialist clinics incur costs if vaccinations are provided through them, and not all have the funding or resources to do so. Additionally, guidelines are based on limited evidence in HIV-infected children, especially those with severe immune deficiency, causing uncertainty as to optimal practice. Approximately 20% of HIV-infected children nationally have a CD4% <20 (http://www.chipscohort.ac.uk/summary_data.asp; accessed 8 July 2010). This may contribute to the incomplete coverage observed for MMR in our study. Few studies have assessed the immunization status of HIV-infected children in industrialized countries. Like ours, recent Swiss and Spanish studies found lower immunization coverage in this population than in the general public [3,4]. A study from Texas found no difference between HIV-infected patients and the general population for diphtheria, tetanus, acellular pertussis and inactivated polio vaccine (DTaP-IPV) and MMR, although vaccine coverage was low overall [5]. We conclude that immunization of HIV-infected children is suboptimal in this London population. Booster doses and nonroutine vaccines are most commonly omitted. Immigrant children are particularly likely to be under-immunized. As life expectancy and the proportion of immigrant HIV-infected children increase, appropriate routine and catch-up immunization becomes more important. Development of evidence-based recommendations and standards for immunization of HIV-infected children, improved accessibility of immunization records, and opportunistic immunization in clinics may all improve this situation.