Immunogenicity, immunologic memory, and safety following measles revaccination in HIV-infected children receiving highly active antiretroviral therapy

Subacute myoclonic measles encephalitis - An opportunistic HIV-associated infection

Introduction

An unusual cluster of myoclonic epilepsy was observed in a Romanian pediatric HIV cohort concurrent with measles outbreaks. We describe this particular form of subacute measles encephalitis (SME) in a group of HIV-infected children and adolescents with severe immunosuppression.

Methods

This is a single-center study, starting in 1997 and covering 4 measles outbreaks in Romania. The presumptive diagnosis of subacute myoclonic measles encephalitis (SMME) was based on: (1) epidemiological data, previous measles episode or presumed contact with measles virus (MV), (2) clinical presentation with initial localized myoclonic jerks with rapid extension and subsequent motor deficit with preserved mental status, and (3) neuroimaging studies revealing cortical gray matter lesions. Definitive diagnosis was based on a neuropathological exam and immunohistochemistry of brain tissues, and measles RNA detection in the cerebrospinal fluid (CSF).

Results

Thirty-six patients were diagnosed with a particular form of SME during consecutive measles outbreaks in Romania: 1996-1998 (22); 2005-2008 (12); 2010-2011 (1) and 2016-2018 (1). Most children were born in the late 80s and had parenterally acquired HIV infection in early childhood. Before the episode of SMME, 11 patients had confirmed measles, while the rest, without typical rash, had a respiratory tract infection and/or presumed previous measles contact. In all patients, the clinical onset was sudden, with unilateral myoclonus. MRI findings revealed mainly focal cortical gray matter lesions. Neurologic symptoms progressed rapidly to coma and death in most patients. Three patients survived SMME, they had higher CD4 count at onset, slower progression of neurological symptoms, and benefit of immune recovery with cART. Immunocytochemistry studies revealed MV in the brain with a pattern suggesting an ascending viral neural infection. MV was isolated from CSF in 7 out of 8 patients. Sequence analysis of MV RNA from both nasopharyngeal swabs and CSF was available for one patient with similar N-450 strain characteristics.

Conclusion

During an outbreak of measles, neurological manifestations, especially myoclonus in immunosuppressed patients, can be related to measles even in the absence of an acute episode. This particular form of subacute myoclonic measles encephalitis is an opportunistic fatal disease. Immune recovery due to effective antiretroviral treatment might increase survival.

Seroconversion and persistence of neutralizing antibody response after yellow fever vaccination in patients with perinatally acquired HIV infection

OBJECTIVES

To describe the dynamics of neutralizing antibody (NAbs) response after yellow fever (YF) vaccine in young adults and adolescents with perinatally acquired HIV (pHIV).

DESIGN

A retrospective cross-sectional study at three time points around YF vaccination and a matched case-control comparison of NAbs titers several years after YF vaccination.

METHODS

We selected patients who had both documented YF vaccination and perinatally acquired HIV (n = 46). The NAbs titers were measured in plasma samples from the following three time points: during the two years before (TP0), within the year after (TP1) and >1 year after (TP2) administration of the YF vaccine. The impact of perinatal infection was assessed by comparing pHIV YF vaccinees with 44 controls infected with HIV during adulthood.

RESULTS

The median time between the YF vaccine and TP1 and TP2 was 123 days and 7.3 years, respectively. After YF vaccination, 85% of vaccinees experienced seroconversion. The proportion of pHIV patients with NAbs above the protective threshold was stable between TP1 and TP2 (91% and 86%, respectively) but levels of NAbs decreased significantly between TP1 and TP2 (P = 0.0122). The case-control analysis found slightly higher geometrical mean titers (GMT) in pHIV than patients infected during adulthood.

CONCLUSIONS

Patients with pHIV showed high seroconversion rate and NAbs persistence at levels above the protective threshold after first YF vaccination. However, a decline in antibody levels over time suggests that at least one revaccination may be necessary to maintain circulating antibodies, contrary to recommendations for the general population.

Getting Treatment and Care Services Right for Children and Adolescents to Reach High Viral Suppression

In August 2014, PEPFAR and the Children's Investment Fund Foundation launched the Accelerating Children's HIV/AIDS Treatment (ACT) initiative with the aim of doubling the number of children on antiretroviral treatment in 9 African countries. Increasing rates of pretreatment drug resistance and use of suboptimal treatment regimens and formulations result in poor adherence and high rates of viral failure. Supporting adherence and ensuring appropriate treatment monitoring are needed to maximize duration of first-line treatment and enable timely sequencing to subsequent lines of antiretroviral treatment. Although timely antiretroviral treatment is the core of clinical care for infants, children and adolescents living with HIV, ensuring a broader package of biomedical and non-biomedical interventions is also required to address highly prevalent comorbidities among children living with HIV. Providing such a comprehensive package has been challenging for health care workers who lack the necessary skills and confidence to care for pediatric populations. Efforts to simplify clinical management and specific training and mentorship are needed to address these challenges. In this article, we review the progress made during the ACT initiative and the persistent challenges in achieving and maintaining virological suppression across the age spectrum. We identify innovations needed to build on the success of the ACT initiative. Despite the challenges, achieving high levels of virological suppression in children and adolescents is possible. The complexity of pediatric HIV treatment can be offset as antiretroviral regimens become more effective, tolerable, and easier to prescribe and administer. Meanwhile, basic programmatic elements to address comorbidities as well as support health care workers remain critical. In this article we review the progress made through the ACT initiative, as well as identify innovations needed to address persistent challenges to viral suppression across the age spectrum.

Seroprevalence of measles vaccine antibody response in vertically HIV-infected children, in Morocco

BACKGROUND

The widespread use of an effective and safe vaccine to measles has substantially decreased morbidity and mortality from this epidemic. Nevertheless, HIV-infected children vaccinated against measles may develop an impaired vaccine response and remain susceptible to this disease. In Morocco, infants are routinely vaccinated against measles, regardless of their HIV serostatus. An evaluation of the immunization of these children may be of paramount importance to implement timely measures aimed at preventing measles transmission.

METHODS

In this study, we have enrolled 114 children vaccinated against measles, 50 children prenatally infected with HIV and 64 HIV-uninfected children. For all children, blood samples were taken to measure anti-measles IgG by EIA and CD4 count by flow cytometry. Additionally, HIV viral load was determined by automated real time PCR, for HIV-infected children.

RESULTS

The seroprotective rate of IgG anti-measles antibodies was significantly lower among HIV-infected children (26%) compared with HIV-uninfected children (73%) (p < 0.001). Within HIV-infected children group, the comparison of variables between children without seroprotective seroconversion to measles and those with seroprotective immunity, displayed that sex and age were not statistically different, p > 0.999 and p = 0.730, respectively. However, CD4 count was lower among children with negative serostatus to measles (23% versus 32%, p < 0.001). Furthermore, viral load was higher, with 2.91 log10 ± 2.24 versus 1.7 log10 ± 1.5 (p = 0.042). Finally, 62% of children with a negative vaccine response to measles were under HAART therapy, versus 92% (p = 0.008).

CONCLUSION

The majority of HIV-infected children vaccinated against measles develop a suboptimal seroprotective titer, and therefore remain at risk for this highly infectious disease. These data in combination with international recommendations, including recent WHO guidance on vaccination of HIV-infected children, suggest there is a need for national measures to prevent these children from measles.

Safety and Immunogenicity of Measles Vaccination in HIV-Infected and HIV-Exposed Uninfected Children: A Systematic Review and Meta-Analysis

BACKGROUND

HIV-infected and HIV-exposed uninfected (HEU) children have an increased risk of measles that may be due to altered immune responses or suboptimal timing of measles vaccination. We aimed to evaluate the safety and immunogenicity of measles vaccination in HIV-infected and HEU children.

METHODS

For this systematic review and meta-analysis, we searched PubMed, Embase, Cochrane Library, CINAHL, Global Health Library and IndMED on May 9, 2018. Studies were included if they reported on safety or seroresponse (either seroprotection/seropositivity/seroconversion) after measles vaccination in HIV-infected or HEU children. We calculated pooled estimates to compare immunogenicity outcomes between HIV-infected, HEU and HIV-unexposed children, using risk ratios [RRs] (with 95%CIs). PROSPERO registration number: CRD42017057411.

FINDINGS

Seventy-one studies met the inclusion criteria (15,363 children). Twenty-eight studies reported on safety; vaccine-associated adverse events and deaths were uncommon. Sixty-two studies reported on immunogenicity, 27 were included in the meta-analysis. HIV-infected children had lower seroresponse rates after primary vaccination compared with HIV-unexposed (RR 0.74; 95%CI: 0.61-0.90, I 2  = 85.9%) and HEU children (0.78; 0.69-0.88, I 2  = 77.1%), which was mitigated by antiretroviral therapy and time interval between vaccination and serology. HEU and HIV-unexposed children had similar seroresponses. Vaccination at 6-months resulted in similar proportions of HIV-infected children having seroresponse compared with HIV-unexposed (0.96; 0.77-1.19) and HEU children (1.00; 0.73-1.37, I 2  = 63.7%).

INTERPRETATION

Primary measles vaccination at 6-months of age may provide protection against measles during early infancy in settings with high prevalence of maternal HIV-infection, however, further studies are needed to evaluate this strategy in HEU children and HIV-infected children receiving antiretroviral therapy.

FUNDING

South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation in Vaccine Preventable Diseases; Medical Research Council: Respiratory and Meningeal Pathogens Research Unit.

Prevalence and risk factors of measles seronegativity in a cohort of HIV-positive subjects: a retrospective study

OBJECTIVES

Measles infection is a vaccine-preventable disease currently resurging in Europe. HIV-infected subjects are at higher risk of complications following measles infection. We investigated the risk factors associated with being seronegative in a cohort of HIV-infected subjects.

METHODS

All HIV-infected subjects in our cohort who had a measles serological test performed between December 2005 and May 2017 were retrospectively identified. A measles immunoglobulin G (IgG) titre > 275 mIU/mL was considered protective. Risk factors were analysed using logistic regression.

RESULTS

Measles serology was available in 273 of 3124 subjects in active follow-up (8.7%). The prevalence of measles seronegativity was 21.6% (59 of 273). In the univariate analysis, being born after 1970 and HIV infection by vertical transmission were both associated with a higher risk of measles seronegativity, while a nadir CD4 T-cell count < 200 cells/μL was associated with a lower risk of measles seronegativity. In the multivariate analysis, only being born after 1970 [odds ratio (OR) 4.9; 95% confidence interval (CI) 1.3-18.7] and vertical transmission (OR 7.7; 95% CI 3.3-18.3) were significantly associated with seronegativity. Among the vertically infected subjects with measles-mumps-rubella (MMR) immunization documentation, the median number of doses of vaccine received before testing was 2 (range 1-3).

CONCLUSIONS

HIV-infected subjects born after 1970 and vertically infected subjects should be screened for measles seropositivity.

Sustained Responses to Measles Revaccination at 24 Months in HIV-infected Children on Antiretroviral Therapy in Kenya

BACKGROUND

There are limited data on whether HIV-infected children in resource-limited countries who are receiving antiretroviral therapy (ART) are able to produce sustained, protective levels of measles antibody after multiple measles vaccinations.

METHODS

We administered an additional measles vaccine to HIV-infected children 15 months to 12 years of age receiving ART in Nairobi, Kenya. Measles antibody concentrations were determined by enzyme-linked immunosorbent assay at enrollment, 1 month, 12 months and 24 months post revaccination.

RESULTS

At enrollment, 125 (54%) of 232 study participants had protective concentrations of measles antibody. Measles seropositivity increased to 98% of all children at 1 month post revaccination but decreased to 71% at 12 months and 60% at 24 months post revaccination. Measles seroconversion and sustained measles seropositivity among those who were measles seronegative at enrollment was 25% at 24 months post revaccination. In this group, 39% of children with <50 copies/mL plasma HIV RNA measles seroconverted compared to 4% of children with plasma HIV RNA ≥1000 copies/mL (P = 0.018).

CONCLUSIONS

Measles revaccination can result in a sustained antibody response in a subset of HIV-infected children receiving ART, especially among those with HIV suppression.

Vaccinations for the HIV-Infected Adult: A Review of the Current Recommendations, Part II

Vaccination is a critical component for ensuring the ongoing health HIV-infected adults. Since this group may have reduced immune responses and shorter durations of protection post-vaccination, HIV-specific guidelines have been published. This review article provides a comprehensive discussion of the current guidelines and evidence-based data for vaccinating HIV-infected adults, including data on dosing schedules, immunogenicity studies, and safety. In the current paper, part II of the review, live vaccines, as well as vaccines for travelers and specific occupational groups, will be discussed.

Vaccination coverage in a cohort of HIV-infected patients receiving care at an AIDS outpatient clinic in Espírito Santo, Brazil

This cross-sectional study assessed the immunization status of human immune deficiency virus (HIV)-infected patients receiving care at an outpatient clinic in Brazil. The sociodemographic characteristics, CD4 count and HIV viral load of 281 out of 612 adult outpatients were analyzed. A total of 331 patients were excluded because of no availability of vaccination cards. Chi-square or Fisher's exact test were used. Immunization coverage was higher for diphtheria/tetanus (59.79%) and hepatitis B (56.7%), and lowest for hepatitis A (6.8%) and for meningococcal group C (6%). Only 11.74% of the patients had received the influenza virus vaccine yearly since their HIV-infection diagnosis. No vaccination against influenza (p<0.034) or hepatitis B (p<0.029) were associated with CD4 counts <500cells/mL; no vaccination against flu or pneumococcus were associated with detectable HIV viral load (p<0.049 and p<0.002, respectively). Immunization coverage is still very low among HIV-infected adults in this setting despite recommendations and high infection-related mortality.

Measles and Rubella Seroprevalence Among HIV-infected and Uninfected Zambian Youth

BACKGROUND

Measles and congenital rubella syndrome remain significant causes of morbidity and mortality despite available vaccines. HIV-infected youth may be at increased risk of measles because of greater waning immunity after vaccination. At a population level, they constitute a potentially large pool of susceptibles to measles and rubella. More data among HIV-infected youth in sub-Saharan Africa are needed to guide vaccination policy and control strategies.

METHODS

This cross-sectional study was nested within 2 ongoing studies of malaria and HIV in Zambia. Dried blood spot cards from youth (5-15 years) in these studies from 2009 to 2013 were tested for IgG antibodies to measles and rubella viruses. HIV-uninfected youth, HIV-infected treatment-naive youth and HIV-infected youth receiving antiretroviral therapy (ART) were compared.

RESULTS

A total of 617 HIV-uninfected, 144 HIV-infected treatment-naive and 128 HIV-infected youth receiving ART were included in this study. The proportion seropositive for measles virus was significantly higher among HIV-uninfected youth (92.5%) compared with HIV-infected treatment-naive youth (74.1%) and HIV-infected youth receiving ART (71.9%). No differences by age were observed. The proportion seropositive for rubella virus was significantly higher among HIV-uninfected youth (54.7%) compared with HIV-infected treatment-naive youth (41.7%) and HIV-infected youth receiving ART (49.6%), with increases observed by age for all groups.

CONCLUSIONS

Measles seroprevalence was lower among HIV-infected than uninfected youth, consistent with waning immunity after measles vaccination. HIV-infected youth would benefit from revaccination. Half of all youth in rural Zambia were susceptible to rubella and may need targeting for catch-up rubella campaigns when measles-rubella vaccine is introduced.

Four-year persistence of type-specific immunity after quadrivalent human papillomavirus vaccination in HIV-infected children: Effect of a fourth dose of vaccine

OBJECTIVE

Although HIV-infected children are recommended to receive quadrivalent human papillomavirus vaccine (QHPV) there is limited information on their response to QHPV. This study in HIV-infected children, evaluated the magnitude and duration of immune responses to QHPV. This report describes type-specific serum antibody responses over a 4-to-5year period after either 3 or 4 doses of QHPV.

DESIGN/METHODS

HIV-infected children, ages 7-to-11years, received 3 doses of QHPV (n=96) or placebo (n=30). At 72weeks QHPV recipients received a fourth dose (n=84), while placebo recipients began the 3-dose QHPV schedule (n=27). HPV serotype-specific antibody was determined, by competitive Luminex immunoassay (cLIA) and IgG Luminex immunoassay, at 2, 3.5, and 4-to-5years after the last dose of QHPV in each treatment arm.

RESULTS

At 4-to-5years after the last dose of QHPV, antibody titers were significantly higher in 4-dose than in 3-dose group. However, the proportion of vaccinees with a seroresponse in the cLIA assay was not different between the two groups (86-93% for HPV types 6, 11, and 16, and 64% for HPV type 18). These results were very similar to the seroresponse rate in these HIV-infected children at 1month after completing vaccination.

CONCLUSIONS

Children with well-controlled HIV infection who receive 3 doses of the QHPV vaccine maintain seropositivity and antibody levels that are generally similar to children of the same age who are not HIV-infected. Antibody titer correlated strongly with low log HIV RNA, low CD8%, and high CD4%. Additionally, a fourth dose of vaccine in HIV-infected children produces a marked rise in antibody characteristic of an anamnestic response and persistence of high antibody levels. Study identification: IMPAACT P1085 (V501-021). CLINICALTRIALS.GOV identifier: NCT01206556.

HIV-associated sub-acute sclerosing panencephalitis - an emerging threat?

Earlier age of measles virus infection predisposes to development of sub-acute sclerosing panencephalitis (SSPE) and this risk is heightened in HIV-infected children. We describe a HIV-infected young adult on antiretroviral therapy, presenting with a non-classical, fulminant form of SSPE to highlight the unpredictable nature of measles presentation. The recent spate of measles outbreaks due to virus introduction in populations with sub-optimal vaccine coverage or waning immunity and co-existing paediatric HIV cohorts is a cause for concern.

Safety and immunogenicity of a live attenuated pentavalent rotavirus vaccine in HIV-exposed infants with or without HIV infection in Africa

OBJECTIVE

Although many HIV-infected (HIV+) and HIV-exposed but uninfected (HEU) infants have received live rotavirus vaccines since the WHO recommended universal administration of these vaccines to infants, there has been limited prospective information on their safety and immunogenicity in either group of infants.

DESIGN/METHODS

We performed a randomized, double-blinded, placebo-controlled trial of the safety and immunogenicity of oral pentavalent rotavirus vaccine (RV5) administered to HIV+ and HEU infants in four African countries. Ninety-three percent of HIV+ infants were receiving antiretroviral therapy prior to vaccination. Participants were followed for safety. Immune responses were measured 14 days after three doses of RV5, including serum antirotavirus neutralizing and IgA antibodies, IgA antibody in stool, and antirotavirus memory B and T-cell FluoroSpot. Shedding of RV5 in stool was monitored.

RESULTS

A total of 76 HIV+ and 126 HEU infants were enrolled from 2009 to 2013. No significant differences were found in adverse event rates, including grade 3 events, between RV5 and placebo recipients, for either HIV+ or HEU infants. The proportion of antirotavirus IgA responders (at least three-fold increase from baseline) after RV5 administration was 81% in both HIV+ and HEU infants, which was approximately 2.5-fold higher than in placebo recipients (P < 0.001). Neutralizing antibody responses to three of five serotypes were significantly higher after RV5 regardless of HIV status, and those of HIV+ infants were equal or greater than responses of HEU infants to all five serotypes. Only one HIV+ RV5 recipient had RV5 isolated from stool.

CONCLUSION

RV5 was immunogenic in both HIV+ and HEU infants and no safety signals were observed.

Evaluation of Immune Response to Measles Component of MMR Vaccine in Children with HIV Infection Receiving Antiretroviral Therapy

BACKGROUND

Children with HIV (CLHIV) respond poorly to primary immunization with measles vaccine and those responding tend to lose protective titer of antibodies by 2-3 years old. Revaccinating CLHIV after immune reconstitution with antiretroviral therapy (ART) may result in good seroconversion, thereby conferring them protection from measles. The objective was to study prevalence of measles antibodies in CLHIV receiving ART before and after immunization with MMR vaccine.

METHODS

CLHIV in the age 5-18 years receiving ART for >6 months and with CD 4 count >15% were included in this prospective study. Their serum was assayed for IgG measles antibodies by qualitative immune-enzymatic determination using enzyme linked immunosorbent assay. The subjects were then immunized with a single dose of MMR vaccine. A repeat venous sample was assayed for measles antibodies 8-12 weeks after immunization.

RESULTS

Sixty-six subjects (46 males, 20 females, mean age 10.4 ± 2.8 years) were enrolled. The mean duration of ART was 3.4 ± 1.5 years and median CD4 count 716.5 μ/L (interquartile range: 563.3-950). At enrollment, 16 (24.2%) subjects tested positive, 8 (12.1%) equivocal and 42 (63.6%) negative for measles antibodies. After 8-12 weeks of immunization, 62 (93.3%) tested positive, 1 (1.5%) equivocal, and 3 (4.5%) negative. There was no difference among the seropositive and seronegative subjects postimmunization with respect to age, sex, duration of ART, nutritional status, CD4 count, or WHO clinical stage. No serious adverse reaction was observed to vaccination.

CONCLUSIONS

MMR vaccine leads to an excellent seroconversion to measles component of vaccine in immune-reconstituted CLHIV.

Low vaccine coverage among children born to HIV infected women in Niamey, Niger

BACKGROUND

The effect of mother's HIV-status on child vaccination is an important public health issue in countries with high HIV prevalence. We conducted a study in a primary healthcare center located in Niamey, the capital of Niger, which offers free of charge services to HIV positive and/or underprivileged mothers, with the aim of assessing: 1) vaccination coverage for children 0-36 months old, born to HIV-infected mothers, and 2) the impact of maternal HIV status on child vaccination.

METHODS

Mothers of children less than 36 months old attending the center were interviewed, to collect information on vaccines administered to their child, and family's socio-demographic characteristics.

RESULTS

Overall, 502 children were investigated. Children of HIV-seropositive mothers were less likely to receive follow up vaccinations for Diphtheria-Tetanus-Pertussis (DTP) than those of HIV-seronegative mothers, with a prevalence ratio (PR) of 2.03 (95%CI: 1.58-2.61). Children born to HIV-seropositive mothers were less likely to miss vaccination for MMR than those born to HIV negative mothers, with a RR of 0.46 (95%CI: 0.30-0.72).

CONCLUSIONS

Vaccine coverage among children born to HIV infected mothers was rather low. It is important to favor access to vaccination programs in this population.

Immunization of children with secondary immunodeficiency

The main causes of secondary immunodeficiency at a pediatric age include infectious diseases (mainly HIV infection), malignancies, haematopoietic stem cell or solid organ transplantation and autoimmune diseases. Children with secondary immunodeficiency have an increased risk of severe infectious diseases that could be prevented by adequate vaccination coverage, but vaccines administration can be associated with reduced immune response and an increased risk of adverse reactions. The immunogenicity of inactivated and recombinant vaccines is comparable to that of healthy children at the moment of vaccination, but it undergoes a progressive decline over time, and in the absence of a booster, the patients remain at risk of developing vaccine-preventable infections. However, the administration of live attenuated viral vaccines is controversial because of the risk of the activation of vaccine viruses. A specific immunization program should be administered according to the clinical and immunological status of each of these conditions to ensure a sustained immune response without any risks to the patients' health.

Immunity to Measles, Mumps, and Rubella in US Children With Perinatal HIV Infection or Perinatal HIV Exposure Without Infection

BACKGROUND

Children with perinatal human immunodeficiency virus (HIV) infection (PHIV) may not be protected against measles, mumps, and rubella (MMR) because of impaired initial vaccine response or waning immunity. Our objectives were to estimate seroimmunity in PHIV-infected and perinatally HIV-exposed but uninfected (HEU) children and identify predictors of immunity in the PHIV cohort.

METHODS

PHIV and HEU children were enrolled in the Pediatric HIV/AIDS Cohort Study (PHACS) at ages 7-15 years from 2007 to 2009. At annual visits, demographic, laboratory, immunization, and clinical data were abstracted and serologic specimens collected. Most recent serologic specimen was used to determine measles seroprotection by plaque reduction neutralization assay and rubella seroprotection and mumps seropositivity by enzyme immunoassay. Sustained combination antiretroviral therapy (cART) was defined as taking cART for at least 3 months.

RESULTS

Among 428 PHIV and 221 HEU PHACS participants, the prevalence was significantly lower in PHIV children for measles seroprotection (57% [95% confidence interval {CI}, 52%-62%] vs 99% [95% CI, 96%-100%]), rubella seroprotection (65% [95% CI, 60%-70%] vs 98% [95% CI, 95%-100%]), and mumps seropositivity (59% [95% CI, 55%-64%] vs 97% [95% CI, 94%-99%]). On multivariable analysis, greater number of vaccine doses while receiving sustained cART and higher nadir CD4 percentage between last vaccine dose and serologic testing independently improved the cumulative prediction of measles seroprotection in PHIV. Predictors of rubella seroprotection and mumps seropositivity were similar.

CONCLUSIONS

High proportions of PHIV-infected children, but not HEU children, lack serologic evidence of immunity to MMR, despite documented immunization and current cART. Effective cART before immunization is a strong predictor of current seroimmunity.

Long-term effect of highly active antiretroviral therapy on immunologic features in children

BACKGROUND

Highly active antiretroviral therapy (HAART) has transformed human immunodeficiency virus infection (HIV) into a chronic condition. The effects of long-term HAART on the immune system activity of early infected children are not fully understood. Hence, the aim of this review is to investigate immune system recovery and residual alteration in HIV-infected children receiving HAART in high-income countries.

METHODS

A systematic review was performed by searches of PubMed and references of the relevant articles. Studies published between January 1, 2000 and April 1, 2014 and conducted in high-income countries reporting data on immunological features in HIV-infected children receiving HAART were included in this review.

RESULTS

Fifty-three articles were included in this review. Present knowledge on B-cell and T-cell function, immunoglobulin production, response to vaccine and innate immune system activity in HIV-infected children receiving HAART is discussed.

CONCLUSION

Starting therapy as soon as diagnosis is ascertained and monitoring vaccine response in children under HAART are the most important tools to safeguard immunological function in HIV-infected children.

Susceptibility to Measles Among Perinatally HIV-Infected Adolescents and Young Adults

Among our cohort of adolescents and young adults with perinatally acquired human immunodeficiency virus, few (17.6%) had measles protective antibodies by plaque reduction neutralization (PRN). Agreement was demonstrated between the commercial enzyme immunoassay and the PRN assay (K = 0.59 [95% confidence interval: 0.23-0.95]). Further studies are needed to understand the determinants of immunity in this population.

Vaccination in HIV-infected adults

Vaccines are critical components for protecting HIV-infected adults from an increasing number of preventable diseases. However, missed opportunities for vaccination among HIV-infected persons persist, likely due to concerns regarding the safety and efficacy of vaccines, as well as the changing nature of vaccine guidelines. In addition, the optimal timing of vaccination among HIV-infected adults in regards to HIV stage and receipt of antiretroviral therapy remain important questions. This article provides a review of the current recommendations regarding vaccines among HIV-infected adults and a comprehensive summary of the evidence-based literature of the benefits and risks of vaccines among this vulnerable population.

Measles seropositivity in HIV-infected Kenyan children on antiretroviral therapy

This article describes results from a cross-sectional study among HIV-infected children 15 months to 12 years of age who were receiving antiretroviral therapy. We found a low prevalence of measles IgG seropositivity (45.7%) and identified CD4% ≥ 25 as a predictor. Most HIV-infected children on ART were not measles seropositive and might benefit from revaccination.

Fatal measles virus infection prevented by brain-penetrant fusion inhibitors

Measles virus (MV) infection causes an acute childhood disease that can include infection of the central nervous system and can rarely progress to severe neurological disease for which there is no specific treatment. We generated potent antiviral peptide inhibitors of MV entry and spreading and MV-induced cell fusion. Dimers of MV-specific peptides derived from the C-terminal heptad repeat region of the MV fusion protein, conjugated to cholesterol, efficiently protect SLAM transgenic mice from fatal MV infection. Fusion inhibitors hold promise for the prophylaxis of MV infection in unvaccinated and immunocompromised people, as well as potential for the treatment of grave neurological complications of measles.

Antibody persistence and immunologic memory after sequential pneumococcal conjugate and polysaccharide vaccination in HIV-infected children on highly active antiretroviral therapy

BACKGROUND

The capacity of pneumococcal vaccination to confer memory in HIV-infected children is critical for durable protection.

METHODS

HIV-infected children 2-<19 years administered two doses of pneumococcal conjugate vaccine (PCV7) and one dose of polysaccharide vaccine (PPV) on HAART were randomized 4-5 years later to receive a PCV7 or PPV booster. Total and high avidity antibodies to serotypes 1 (PPV) and 6B and 14 (PCV7 and PPV) were determined by ELISA. Memory was defined as persistence of ≥ 0.5 mcg/mL of serotype-specific antibody on day 0 or change from <0.5 mcg/mL to ≥ 0.5 mcg/mL between day 0 and week 1, or, ≥ 4-fold antibody rise between day 0 and week 1.

RESULTS

Prior to boosting, 4-5 years after the previous PCV7-PCV7-PPV series, geometric mean concentrations (GMCs) were 0.46 mcg/mL (serotype 1), 1.31 mcg/mL (serotype 6B), and 1.47 mcg/mL (serotype 14), with concentrations ≥ 0.5 mcg/mL in 41% (serotype 1) to 82% (serotypes 6B and 14). Memory based on antibody concentration ≥ 0.5 mcg/mL before or 1 week after boosting with PCV7 or PPV was demonstrated in 42-61% for serotype 1 and 87-94% for serotypes 6B and 14, with lower rates based on day 0 to week 1 ≥ 4-fold antibody rise (serotype 1, 3-13%; serotype 6B, 13-31%; serotype 14, 29-53%). Antibody concentrations post-boosting were greater following PCV7 than PPV for serotypes 6B and 14. Ratios of highly avid to total antibody pre- and post-boosting were 0.5-0.8. Predictors of memory included higher CD4% (nadir before HAART and at P1024 and P1061s entry), CD19% (at P1024 and P1061s entry), and antibody response after the PCV7-PCV7-PPV primary series and lower viral load (at P1024 and P1061s entry) and age.

CONCLUSIONS

Protective antibody concentrations, high avidity, and booster responses to PCV7 or PPV indicative of memory were present 4-5 years after PCV7-PCV7-PPV in HIV-infected children on HAART.

Changes in measles serostatus among HIV-infected Zambian children initiating antiretroviral therapy before and after the 2010 measles outbreak and supplemental immunization activities

BACKGROUND

In 2010, Zambia had a large measles outbreak, providing an opportunity to measure changes in measles serostatus following highly active antiretroviral therapy (HAART), exposure to measles virus, and revaccination among children infected with human immunodeficiency virus (HIV).

METHODS

A prospective cohort study of 169 HIV-infected Zambian children aged 9-60 months with a history of measles vaccination was conducted to characterize the effects of HAART and revaccination on measles immunoglobulin G (IgG) serostatus by enzyme immunoassay.

RESULTS

Prior to the measles outbreak, only 23% of HIV-infected children were measles IgG seropositive at HAART initiation. After adjusting for 6-month changes in baseline age and 5% changes in nadir CD4(+) T-cell percentage, HAART was not associated with measles IgG seroconversion. However, 18 of 19 children seroconverted after revaccination. Eight children seroconverted during the outbreak without revaccination and were likely exposed to wild-type measles virus, but none were reported to have had clinical measles.

CONCLUSIONS

Immune reconstitution after HAART initiation did not restore protective levels of measles IgG antibodies, but almost all children developed protective antibody levels after revaccination. Some previously vaccinated HIV-infected children had serological evidence of exposure to wild-type measles virus without a reported history of measles.

Undervaccination of perinatally HIV-infected and HIV-exposed uninfected children in Latin America and the Caribbean

BACKGROUND

Perinatally HIV-infected (PHIV) children may be at risk of undervaccination. Vaccination coverage rates among PHIV and HIV-exposed uninfected (HEU) children in Latin America and the Caribbean were compared.

METHODS

All PHIV and HEU children born from 2002 to 2007 who were enrolled in a multisite observational study conducted in Latin America and the Caribbean were included in this analysis. Children were classified as up to date if they had received the recommended number of doses of each vaccine at the appropriate intervals by 12 and 24 months of age. Fisher's exact test was used to analyze the data. Covariates potentially associated with a child's HIV status were considered in multivariable logistic regression modeling.

RESULTS

Of 1156 eligible children, 768 (66.4%) were HEU and 388 (33.6%) were PHIV. HEU children were significantly (P < 0.01) more likely to be up to date by 12 and 24 months of age for all vaccines examined. Statistically significant differences persisted when the analyses were limited to children enrolled before 12 months of age. Controlling for birth weight, sex, primary caregiver education and any use of tobacco, alcohol or illegal drugs during pregnancy did not contribute significantly to the logistic regression models.

CONCLUSIONS

PHIV children were significantly less likely than HEU children to be up to date for their childhood vaccinations at 12 and 24 months of age, even when limited to children enrolled before 12 months of age. Strategies to increase vaccination rates in PHIV are needed.

Impaired cellular immune response to tetanus toxoid but not to cytomegalovirus in effectively HAART-treated HIV-infected children

Despite of highly active antiretroviral therapy, the response to vaccines in HIV-infected children is poor and short-lived, probably due to a defect in cellular immune responses. We compared the cellular immune response (assessed in terms of IFN-γ production) to tetanus toxoid and to cytomegalovirus in a series of 13 HIV-perinatally-infected children and adolescents with optimal immunovirological response to first line antiretroviral therapy, implemented during chronic infection. A stronger cellular response to cytomegalovirus (11 out of 13 patients) was observed, as compared to tetanus toxoid (1 out of 13; p=0.003). These results suggest that the repeated exposition to CMV, as opposed to the past exposition to TT, is able to maintain an effective antigen-specific immune response in stable HIV-infected pediatric patients and strengthen current recommendations on immunization practices in these children.