ABSTRACT: This paper reviews the English language literature on the safety, immunogenicity and effectiveness in children infected with the human immunodeficiency virus (HIV) of vaccines currently recommended by WHO for use in national immunization programmes. Immunization is generally safe and beneficial for children infected with HIV, although HIVinduced immune suppression reduces the benefit compared with that obtained in HIVuninfected children. However, serious complications can occur following immunization of severely immunocompromised children with bacillus CalmetteGuérin (BCG) vaccine. The risk of serious complications attributable to yellow fever vaccine in HIVinfected persons has not been determined.
WHO guidelines for immunizing children with HIV infection and infants born to HIVinfected women differ only slightly from the general guidelines. BCG and yellow fever vaccines should be withheld from symptomatic HIVinfected children. Only one serious complication (fatal pneumonia) has been attributed to measles vaccine administered to a severely immunocompromised adult. Although two HIVinfected infants have developed vaccineassociated paralytic poliomyelitis, several million infected children have been vaccinated and the evidence does not suggest that there is an increased risk. The benefits of measles and poliovirus vaccines far outweigh the potential risks in HIVinfected children. The policy of administering routine vaccines to all children, regardless of possible HIV exposure, has been very effective in obtaining high immunization coverage and control of preventable diseases. Any changes in this policy would have to be carefully examined for a potential negative impact on disease control programmes in many countries.
Keywords HIV infections/immunology; BCG vaccine/immunology/adverse effects; Measles vaccine/immunology; Poliovirus vaccine, Oral/immunology; Yellow fever vaccine/immunology/adverse effects; Diphtheriatetanuspertussis vaccine/immunology; Hepatitis B vaccines/immunology; Haemophilus vaccines/immunology; Infant; Immunization programs; Guidelines; World Health Organization; Review literature (source: MeSH, NLM).
Mots clés HIV, Infection/immunologie; Vaccin BCG/immunologie/effets indésirables; Vaccin antimorbilleux/immunologie; Vaccin antipoliomyélitique Sabin/immunologie; Vaccin antifièvre jaune/immunologie/effets indésirables; Vaccin diphtérietétanoscoqueluche/ immunologie; Vaccin antihépatite B/immunologie; Vaccin antihémophilus/immunologie; Enfant; Nourrisson; Programmes de vaccination; Lignes directrices; Organisation mondiale de la Santé; Revue de la littérature (source: MeSH, INSERM).
Palabras clave Infecciones por VIH/inmunología; Vacuna BCG/inmunología/efectos adversos; Vacuna antisarampión/inmunología; Vacuna antipolio oral/inmunología; Vacuna contra la fiebre amarilla/inmunología/efectos adversos; Vacuna difteriatétanopertussis/inmunología; Vacunas contra hepatitis B//inmunología; Vacunas contra haemophilus/ inmunología; Vacunas bacterianas/inmunología; Vacunas virales/inmunología; Vacunas atenuadas/inmunología; Niño; Lactante; Programas de inmunización; Pautas; Organización Mundial de la Salud; Literatura de revisión (fuente: DeCS, BIREME).
The majority of children born to women who are infected with human immunodeficiency virus (HIV) do not acquire HIV infection. Of those children who do become infected, most acquire the virus from their mothers at the time of delivery or shortly thereafter. Early in life they are immunologically normal but, in the absence of specific therapy for HIV infection, develop progressive immunodeficiency that affects all aspects of the immune system. The rate of progression to clinically apparent immunosuppression depends on maternal, infant, and viral factors. Accordingly, the safety and effectiveness of vaccines in HIVinfected children varies with age at vaccination and their immune status.
Guidelines for administering immunizations usually make special provisions for children known to have underlying immunodeficiency disorders. The following areas of concern are critical to the development of such guidelines.
Will the effectiveness of a vaccine be impaired because of underlying immune deficiency?
Are persons receiving a live viral vaccine or a bacterial vaccine subject to a significantly increased risk compared with noninfected persons?
Does administering a vaccine significantly affect the rate of HIVassociated disease?
In this paper we review the literature published in English on the safety, immunogenicity and effectiveness of vaccines, including new vaccines that are being introduced in some areas, and critically evaluate WHO's recommendations on the vaccination of HIVinfected persons.
Current WHO recommendations for immunization of children with known or suspected HIV infection
Few adverse events have been observed following the immunization of HIVinfected infants. Consequently, the current WHO guidelines for immunizing children known to have HIV infection and infants born to HIVinfected women differ only slightly from the general guidelines for other infants (1). WHO's policy is based on the potential severity of vaccine preventable diseases in HIVinfected children, on vaccine safety and immunogenicity, and on the degree of HIVinduced immunosuppression. Children with known or suspected asymptomatic HIV infection should receive all recommended vaccines in accordance with nationally recommended schedules subject to the modifications listed below.
An extra dose of measles vaccine is recommended at 6 months of age in order to provide protection at a younger age than for nonHIVinfected infants and to improve protection against measles.
Individuals with symptomatic HIV infection should not receive live attenuated BCG vaccine. Administration of BCG vaccine to HIVexposed infants should be based on the risk of tuberculosis. If this risk is high, BCG vaccine should be administered at birth to children with possible HIV infection according to the standard schedule of the Expanded Programme on Immunization. If BCG vaccine remains on the schedule of a national immunization programme and the risk of tuberculosis is low, this vaccine should not be administered to children with suspected HIV infection.
Individuals with symptomatic HIV infection should not receive live attenuated yellow fever vaccine.
Immunogenicity and effectiveness
Following primary immunization in infancy, 40100% of symptomatic and asymptomatic HIVinfected children respond to diphtheria and tetanus toxoids by developing protective levels of diphtheria and tetanus antitoxins (Table 1). However, HIVinfected children and adults develop lower geometric mean antitoxin titres and are more likely than uninfected persons to lose antibody within a few years after vaccination. Some studies have correlated antibody titres with CD4+ Tlymphocyte counts (Table 1). Comparable data for pertussis vaccines are more limited and their interpretation is more difficult since serological correlates of protection have not been identified. The available data suggest that the proportion of children who seroconvert and the geometric mean antibody titres to pertussis toxin are lower for HIV infected children than for healthy controls (2). There is no evidence that HIVinfected children have higher vaccine failure rates than HIVuninfected children following diphtheria, tetanus or pertussis immunization, but there have been no rigorous studies of the effectiveness of diphtheriatetanus pertussis vaccine in HIVinfected children.
Hepatitis B vaccines
The serological response to hepatitis B vaccines is lower for HIVinfected children and adults than for uninfected persons of similar age (Table 2). Serological response rates have varied, but most studies have reported that only 2550% of HIVinfected children have developed protective antibodies. As with tetanus and diphtheria toxoids, response rates appear to be higher for younger children and in some studies correlate with CD4+ Tlymphocyte counts. Attempts to overcome the decreased response by administering higher doses or extra doses of hepatitis B vaccine have not been promising in children (3, 4). However, one study of 20 HIVinfected adults reported that seven of the nine individuals who failed to respond to the initial threedose series developed a protective antibody response after three additional doses of hepatitis B vaccine (5). HIVinfected children and adults who respond to hepatitis B vaccine have a more rapid decline in antibody titre than uninfected persons. For example, only 42% of HIVinfected children who seroconverted after the primary threedose series or after receipt of the adult dose of hepatitis B vaccine had protective antibody titres 1318 months after immunization (6). Longterm followup studies suggest that most HIVuninfected children and adults have continued protection against becoming clinically ill and chronic HBsAg carriers after exposure, despite loss of detectable antibody (7). It is not known whether such protection occurs in HIVinfected persons with undetectable antibody levels. In immunologically normal persons, however, loss of detectable antibody after developing a protective antibody response (> 10 mIU) does not mean that protection against hepatitis B has been lost.
Polysaccharide and polysaccharideprotein conjugate vaccines
In the absence of acquired immunodeficiency syndrome (AIDS) or profoundly diminished CD4+ Tlymphocyte counts, 3786% of HIVinfected children developed protective antibody responses to Haemophilus influenzae type b conjugate vaccine, but the geometric mean titres were lower than those reported for HIVuninfected persons of similar ages (812). Antibody levels decline more rapidly in HIVinfected children but booster doses of vaccine induce rapid increases in the levels, suggesting the retention of immunological memory in many HIVinfected children (11). One study reported that antibody titres decreased to below 1 mg/ml in 43% of 48 HIVinfected children one year after vaccination, whereas the corresponding proportion was only 11% for HIVuninfected children (10). The absence of high rates of vaccine failure among HIVinfected children in settings where routine immunization has been introduced suggests that many such children are protected against invasive disease following immunization with conjugate H. influenzae type b vaccines.
No data are available on the response of HIVinfected children or adults to meningococcal polysaccharide or conjugate vaccines, but the response to 23valent pneumococcal polysaccharide vaccine is poorer than that of HIVuninfected persons. The antibody response to a glycoprotein conjugate pneumococcal vaccine was better than that of the polysaccharide vaccine in HIVinfected persons, except for those with very low CD4+ Tlymphocyte counts (13, 14). Since polysaccharides are processed as Tindependent antigens, the immune response is not affected by HIVinduced impairment of the immune response to the same extent as with Tdependent antigens. However, the antibody response to specific pneumococcal polysaccharide serotypes varies, some serotypes eliciting poor antibody responses in HIVinfected persons with CD4+ Tlymphocyte counts below 200 cells/ mm3 (15). In HIVinfected Ugandan, adults the 23valent pneumococcal polysaccharide vaccine did not prevent first episodes of invasive pneumococcal disease (16).
Live bacterial vaccines
Bacillus CalmetteGuérin (BCG) vaccine
The tuberculin skin test is the only practical tool for determining the response to BCG vaccination, but the diameter of the skin test following immunization is not a good predictor of protection against Mycobacterium tuberculosis disease. In Rwanda, only 37% of HIVinfected infants developed a skin test response exceeding 6 mm in diameter after BCG vaccination, whereas the corresponding proportions for HIVuninfected infants born to HIVinfected women and for infants born to HIVuninfected women were 57% and 70%, respectively (17).
The protection conferred by BCG vaccination against tuberculous meningitis and miliary tuberculosis in HIV uninfected populations varies widely, most probably because of differences in BCG strains and in study methodologies, but a recent metaanalysis indicated that the overall protection was approximately 80% (18). In Zambia the proportion of children with BCG scars (83%) was the same for 30 HIVinfected children with tuberculosis and for 18 such children who did not have tuberculosis, i.e. there was no evidence of protection from BCG vaccination (19). This study did not have sufficient power to evaluate protection against tuberculous meningitis or miliary disease. Studies of tuberculosis in adults who had received BCG vaccine in infancy have not shown a clear protective benefit (20, 21). These data are not adequate to permit definitive conclusions about the effectiveness of BCG vaccine to protect HIVinfected children or adults against tuberculosis.
Live viral vaccines
Oral poliovirus vaccine (OPV)
The proportion of HIVinfected children who responded to three doses of OPV exceeded 90% in most studies (Table 3). In the Democratic Republic of Congo (formerly Zaire), 97% of HIVinfected children developed protective antibody titres to poliovirus types 1, 2, and 3 after three doses of OPV (22). However, this study was conducted when there was widespread circulation of wildtype polioviruses, which could have contributed to the high proportion of children with antibody. Although no direct estimates of the efficacy of poliovirus vaccine have been conducted in HIVinfected children, wild type polioviruses have been eliminated from several countries with high prevalence rates of HIV infection.
Measles virus vaccine
Antibody response to measles vaccine is impaired in HIV infected persons (Table 4). Approximately onefourth to one third of HIVinfected children have responded to a single dose of standardtitre measles vaccine in most prospective studies (2326). In a study of HIVseropositive children in Zaire, 65% had protective titres of measles antibody three months after measles vaccination at 9 months of age; only 36% of 11 symptomatic children seroconverted, whereas 77% of 26 asymptomatic children did so (23). The response to a second dose of vaccine varied but was generally poor (25, 2730). In crosssectional studies there were wide variations in the age at immunization, the number of vaccine doses received, the interval between immunization and assay, the type of measles antibody assay, and the degree of immunosuppression at the time of assessment. In children, the prevalence of measles antibody varied from 17% to 100%, with a median value of 60% (24, 25, 27, 2933). Most HIVinfected adults, however, were seropositive for measles antibodies (34, 35). An association between lack of measlesspecific antibodies after vaccination and low CD4+ Tlymphocyte counts (3) was documented in one prospective study (25) and two crosssectional studies (30, 33). In a study of Ugandan children, a poor antibody response to measles vaccine was associated with stunting but not with HIV infection (36). HIVinfected children appear to experience a more rapid decline in measles antibodies than HIVuninfected children (30), the median time to loss of antibody detectable by enzyme immunosorbent assay was 30 months in a study of 17 HIVinfected children (33).Placental transfer of maternal antibodies, including antibodies to measles, may be impaired in HIVinfected women (32, 37, 38). The lower amounts of maternal antibody correlated with an improved response to standardtitre measles vaccine administered at 6 months of age. Less immunosuppression at 69 months of age may contribute to higher response rates than at 1215 months of age (32). Studies in progress are evaluating the immunogenicity of measles vaccination at 6 and 9 months of age in HIVinfected children.
Experience in southern Africa suggests that the number of measles cases can be reduced in regions of high HIV prevalence by maintaining high immunization rates coupled with periodic supplemental campaigns (39). However, primary and secondary vaccine failures in HIVinfected children and the potential for prolonged measles virus shedding (40) could hinder the longterm control or elimination of measles in regions of high HIV prevalence.
Yellow fever virus vaccine
Limited data suggest that HIVinfected children respond poorly to yellow fever vaccine (41). However, seroconversion rates were high in HIVinfected adults who were not severely immunocompromised (42). Only 3 of 18 HIVinfected children (17%) developed an antibody response to yellow fever vaccine, whereas 74% of 57 HIVuninfected children did so (41). No data are available on protection against disease following yellow fever vaccination of HIVinfected persons. Despite the possibility of reduced protection, it seems justifiable to encourage the use of the vaccine even in areas of high HIV prevalence.
Safety of vaccines in HIVinfected persons
Nonreplicating vaccines are not associated with increased risks of complications in immunocompromised persons. However, a study of HIVinfected Ugandan adults found a higher incidence of pneumonia among recipients of 23valent pneumococcal polysaccharide vaccine than among unvaccinated HIVinfected adults (16). The authors hypothesized that immunization might result in the destruction of polysaccharideresponsive Bcell clones but presented no specific data to support this suggestion. Additional studies are needed on this issue.
Complications arising from BCG vaccination include regional, extraregional localized, and disseminated disease. The rates of these complications in HIVuninfected children vary. BCG causes local ulcers and regional lymphadenitis in normal hosts at rates varying from 4 to 30 per 1000 vaccinated infants, depending on the vaccine strain, the technique of administration, and the dose (43). There are several reports of regional lymphadenitis, poorly healing ulcers, and fistulae in HIVinfected infants (Table 5). Administration of BCG to HIVinfected children in the first month of life is associated with relatively low rates of complications because immune suppression takes several months to develop. In direct comparisons, the rates of these complications have been similar in HIVinfected and HIVuninfected infants, but lymphadenitis has been more severe in HIVinfected children.
More than 28 cases of disseminated BCG infection have been reported in HIVinfected children and adults (Table 5) (44, 45). Because the diagnosis cannot be made on clinical criteria alone and requires laboratory facilities to culture the organism and differentiate it from other mycobacteria, this complication has undoubtedly occurred in more HIVinfected individuals than has been reported in the published literature. Although disseminated disease usually occurs between several months and a few years following vaccination, it was reported in one 30yearold with HIV infection who received BCG vaccine at birth (46). Disseminated BCG infection is more likely to occur when the vaccine is administered to individuals with clinical AIDS or advanced immunosuppression. Progressive immune suppression can lead to the reactivation of latent BCG organisms, causing regional or disseminated disease (46, 47). In one study, however, no cases of disseminated BCG infection were found among 155 adult patients with AIDS who had received BCG vaccine in infancy and whose blood was cultured for mycobacteria (21).
Live viral vaccines
Oral poliovirus vaccine
The risk of vaccineassociated paralytic poliomyelitis is increased in persons with primary B cell immunodeficiency disorders. Nevertheless, in the USA more than 1000 HIVinfected children received at least one dose of OPV without complications before it was known that they or their mothers were HIVinfected, and several thousand HIVinfected children in other countries have been vaccinated. We estimate that, in the 20 years since the HIV epidemic has been recognized, more than 500 000 HIVinfected children have received one or more doses of OPV. Only two HIVinfected children have been reported with vaccineassociated paralytic poliomyelitis following the receipt of OPV (Table 3): a 2year old Romanian girl (48) and a child in Zimbabwe (49). In Romania the rate of vaccineassociated paralytic poliomyelitis in all children was approximately ten times higher than the estimated 1 case per 2.5 million doses administered in the USA and Europe, most probably because of the use of multiple injections (50). The HIV infections in these two children with vaccineassociated paralytic poliomyelitis could be chance associations and not evidence of an increased risk associated with HIV infection. If the risk of vaccineassociated paralytic poliomyelitis is greater for HIVinfected persons, the attributable risk is very low. Studies in progress are evaluating the possibility of prolonged excretion of poliovirus vaccine strain by HIVinfected children.
Measles virus vaccine
Prospective studies revealed that the risk of adverse events in the few weeks following immunization with standardtitre and hightitre measles vaccines was no different for HIVinfected and HIVuninfected children (51), although one HIVinfected adult developed fever, rash, coryza and conjunctivitis 12 days after measles immunization (52). A retrospective survey conducted by the New York City Department of Health found no complications following measles immunization of HIVinfected children (53). Measles vaccine virus was detected by means of the polymerase chain reaction in a 14monthold HIVinfected boy who developed diarrhoea and a febrile illness associated with a 4day generalized rash after receiving measlesmumpsrubella vaccine (54). No evidence of persistent excretion of measles vaccine virus was found in 10 HIV infected children immunized with this vaccine (28).
Only one serious adverse event has been reported following the administration of measles vaccine to an HIV infected person (55). A 20yearold HIVinfected man, who had a very low CD4+ Tlymphocyte count at the time he received a second dose of measlesmumpsrubella vaccine, developed cough and progressive pulmonary infiltrates 10 months after immunization. An open lung biopsy showed giant cell pneumonitis, and measles vaccine virus was identified in the lung tissue. The patient died several months later from the progressive pneumonitis
Yellow fever vaccine
WHO became concerned about the theoretical risk of yellow fever vaccine causing illness in immunocompromised individuals and about early unconfirmed reports of serious adverse events in HIVinfected persons and issued guidelines on avoiding the use of yellow fever vaccine in symptomatic HIV infected individuals (1). Few severe complications attributable to the inadvertent immunization of immunocompromised individuals with yellow fever vaccine have been reported, but experience is limited. Fatal myeloencephalitis caused by yellow fever vaccine was reported in a 53yearold HIVinfected man in Thailand (56), although no adverse events were observed following yellow fever vaccination of two HIVinfected adults (57). Seven cases of severe illness resembling yellow fever, six of them fatal, were reported with evidence of vaccine virus in affected tissues, but there was no evidence of HIV infection (58). These findings are encouraging but more studies are needed in order to confirm the safety of yellow fever vaccine in HIVinfected persons. On the basis of the available information, the authors consider that, in the event of an outbreak, yellow fever vaccine should be administered to the whole population at risk, irrespective of their HIV infection status. Travel clinics for healthy adults are generally more conservative, and administer yellow fever vaccine only to those with adequate CD4+ Tlymphocyte counts.
Effect of vaccination on HIV disease progression
The activation of CD4+ Tlymphocytes following immunization could potentially augment HIV replication and result in accelerated progression to disease. Several, but not all investigators (59) have described increased HIV RNA plasma levels lasting several days following immunization with tetanus toxoid (60) and with influenza (6164), pneumococcal (65, 66) and hepatitis B vaccines (5, 67). Importantly, no investigators have observed prolonged elevation of HIV RNA viral load, decreased CD4+ lymphocyte counts or accelerated HIV disease progression following immunization (68). Although the transient rise in HIV viral load following the administration of tetanus toxoid to pregnant women could theoretically affect the risk of maternalinfant HIV transmission, an increased risk of transmission is unlikely if vaccination occurs at least four weeks before delivery.
The current WHO recommendations for the vaccination of HIVinfected children and adults are appropriate. However, the factors discussed below should be taken into consideration.
Timing of immunizations
Because of the decreased immune response to vaccines with increasing age in HIVinfected children, immunization should take place as early in life as possible in children born to HIV infected women. For hepatitis B vaccine, early immunization is especially important because the risk of becoming a chronic carrier is higher for HIVinfected children and adults than for uninfected persons (69). A preference for immunization at birth should be indicated in countries with a high maternal HIV infection rate as well as in those where there are high rates of perinatal hepatitis B transmission. The limited available data do not suggest that there is a need for administering extra doses of hepatitis B vaccine to HIVinfected children.
Most infants born to HIVinfected women do not acquire HIV infection. BCG vaccine provides some protection against severe disease for children in areas of high risk for tuberculosis. If it were possible to administer BCG vaccine only to HIVuninfected children in the first month of life, the incidence of severe complications from this vaccine could be reduced. However, in most areas it is not practical at this time to identify HIVinfected children early in their lives. The current policy of administering BCG vaccine to all asymptomatic infants at risk of acquiring tuberculosis is appropriate. In regions where the risk of contracting tuberculosis is low, BCG vaccine should not be administered to children with known or suspected HIV infection.
It is not necessary or practical to consider the use of inactivated poliovirus vaccine for children born to HIVinfected women in most countries. Some countries that have been free of wildtype polioviruses for many years routinely use inactivated poliovirus vaccine to vaccinate HIVinfected children. In order to avoid the possible increased risk of vaccineassociated paralytic poliomyelitis, countries where wildtype polioviruses have been eliminated may consider the use of inactivated poliovirus vaccine for immunocompromised HIVinfected children if the necessary resources are available.
Immunocompromised HIVinfected children are at risk of death or severe complications following wildtype measles virus infection. The balance of risk clearly favours measles immunization in regions where there is transmission of wildtype measles virus. If measles virus is circulating in a community, all children, regardless of HIV infection status, should receive measles vaccine. Current WHO policy adequately addresses the need for early measles immunization of children born to HIVinfected women. Although definitive evidence is lacking, an extra dose of standardtitre measles vaccine administered to HIVinfected infants at 6 months of age is likely to result in protective antibody titres because inhibitory maternal antibody titres are low and the immune system is still unimpaired.
Where the chance of contracting wildtype measles virus infection is almost nonexistent, countries with the capacity to monitor an individual's immune status may consider withholding measles vaccine from severely immunocompromised HIVinfected children. Children with moderate levels of immune suppression should continue to receive measles vaccine.
Yellow fever vaccine
Yellow fever vaccine should be withheld from HIVsymptomatic individuals until more information is available on the vaccine's safety for HIVinfected individuals.
Research in several areas (see Box 1) is needed in order to further evaluate and consider future modifications of WHO policies for the vaccination of HIVinfected persons.
This work was supported in part by the World Health Organization and by a cooperative agreement from the Centers for Disease Control and Prevention (CDC) for Clinical Immunization Safety Assessment (CISA) Network.
The authors wish to thank Tina Proveaux for technical and editorial assistance.
Conflicts of interest: Dr Halsey has conducted clinical trials of vaccines supported by Glaxo SmithKline.
Vaccination de l'enfant à risque d'infection par le virus de l'immunodéficience humaine
L'article passe en revue la littérature de langue anglaise concernant l'innocuité, l'immunogénicité et l'efficacité des vaccins actuellement recommandés par l'OMS dans le cadre des programmes nationaux de vaccination. La vaccination est en général sans danger et bénéfique chez l'enfant infecté par le virus de l'immunodéficience humaine (VIH) ; l'immunodépression induite par le VIH diminue cependant le bénéfice, comparé à celui obtenu chez des enfants indemnes d'infection. Le risque de complications graves est toutefois possible après vaccination par le bacille de Calmette et Guérin (BCG) quand l'enfant est gravement immunodéprimé. Le risque de complication postvaccinale grave après vaccination antiamarile de personnes infectées par le VIH n'a pas été déterminé.
Les recommandations de l'OMS pour la vaccination de l'enfant atteint d'infection à VIH et du nourrisson né de mère infectée par le virus diffèrent très peu des recommandations générales. Le vaccin antiamaril et le BCG ne seront pas administrés à l'enfant symptomatique. Un seul cas de complication grave (pneumonie fatale) a été attribué au vaccin antirougeoleux administré à un adulte massivement immunodéprimé. Si deux nourrissons infectés par le VIH ont fait une poliomyélite paralytique postvaccinale, plusieurs millions d'enfants infectés par le VIH ont été vaccinés et les données n'indiquent pas qu'il y ait augmentation du risque. Les avantages des vaccins antirougeoleux et antipoliomyélitique dépassent largement les risques potentiels chez ces enfants. La politique consistant à administrer les vaccins classiques à tous les enfants, quelle que soit leur exposition au VIH, a permis d'obtenir une bonne couverture vaccinale et la maîtrise de maladies évitables. Toute modification de cette politique devra être soigneusement pesée en raison de l'impact négatif qu'elle pourrait avoir dans de nombreux pays sur les programmes de lutte contre les maladies.
Inmunización de los niños en riesgo de infección por el virus de la inmunodeficiencia humana
En este artículo se examina la literatura en inglés sobre la seguridad, inmunogenicidad y eficacia de las vacunas actualmente recomendadas por la OMS para los programas nacionales de vacunación. La inmunización es por lo general segura y beneficiosa para los niños infectados por el virus de la inmunodeficiencia humana (VIH), si bien la inmunodepresión causada por dicho virus atenúa los efectos beneficiosos en comparación con los conseguidos en los niños no infectados por el VIH. Sin embargo, los niños gravemente inmunodeprimidos pueden sufrir graves complicaciones tras la inmunización con la vacuna basada en el bacilo de CalmetteGuérin (BCG). No se ha determinado el riesgo de complicaciones graves atribuibles a la vacuna antiamarílica en personas infectadas por el VIH.
Las directrices de la OMS para inmunizar a los niños con infección por el VIH y los lactantes nacidos de mujeres infectadas por el VIH difieren muy poco de las directrices generales. Hay que evitar la BCG y la vacuna antiamarílica en los niños infectados por el VIH con síntomas. Sólo se ha dado un caso de complicación grave (neumonía mortal) atribuida a la vacuna antisarampionosa administrada a un adulto gravemente inmunodeprimido. Aunque dos lactantes infectados por el VIH han desarrollado poliomielitis paralítica asociada a la vacuna, son varios millones los niños infectados que han sido vacunados, y no hay ningún indicio de que corran un mayor riesgo. Los beneficios que reportan las vacunas contra el sarampión y el poliovirus superan ampliamente los riesgos potenciales en los niños infectados por el VIH. La política de administrar sistemáticamente esas vacunas a todos los niños, independientemente de su posible exposición al VIH, ha contribuido de forma muy eficaz al logro de una alta cobertura de inmunización y de control de enfermedades prevenibles. Cualquier cambio de dicha política debería verse precedido de un detenido examen de las posibles repercusiones negativas en los programas de control de esas enfermedades en muchos países.
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1Assistant Research Professor, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; and W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; USA.
2Medical Officer, Department of Vaccines and Biologicals, World Health Organization, Geneva, Switzerland.
3Professor and Director, Institute for Vaccine Safety, Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA (email: firstname.lastname@example.org). Correspondence should be addressed to this author.
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