Immunity After Childhood Vaccinations in Perinatally HIV-exposed Children With and Without HIV Infection in Latin America

Heterogeneity and Hierarchy of Immune Response to Primary Immunization in HIV-Infected Children on HAART and the Impact of an Additional Dose of Vaccine

The nature of vaccine response inferiority is not well studied in children living with HIV (CLHIV). The authors investigated Hepatitis B Virus (HBV) and Diphtheria/Pertussis/Tetanus toxoid (DPT) vaccination responses following primary immunization in CLHIV (n = 42) and healthy controls (HC) (n = 38) and the effect of an additional vaccine dose. Antibody responses, CD4 and HBV-specific T/B cells were analysed using CMIA/ELISA and flow-cytometry. CLHIV had significantly lower baseline median antibody titres for all vaccines than HC (p <0.02). Differential seroprotection rates observed in CLHIV were, 4.8% for pertussis; 9.5% for HBV; 26.2% for diphtheria and 66.7% for tetanus. WHO staging significantly influenced anti-HBs levels (p = 0.0095). HBsAg-specific CD4+T-cells were significantly higher in CLHIV than HC (p = 0.042). An additional vaccine dose (HBV and Tdap) conferred a higher protection rate for tetanus and diphtheria (p <0.040) in CLHIV. These findings suggest that CLHIV exhibit a hierarchy of vaccine responses affecting antibody levels and protection rate, which was rescued by administering additional vaccine dose.

Follow-up for 3 years of a pediatric population diagnosed in 2018 with mother-to-child transmission of HIV in 8 Latin American countries in the PLANTAIDS cohort

INTRODUCTION

The frequency of mother-to-child transmission (MTCT) of human immunodeficiency virus (HIV) in Latin America has decreased considerably. However, new infections continue to be recorded, and the pediatric population remains one of the most vulnerable groups in this region. The main objective of the study was to describe the clinical, epidemiological and psychosocial characteristics of new diagnoses of HIV MTCT in 2018 in the PLANTAIDS network (Paediatric Network for Prevention, Early Detection and Treatment of HIV in Children) during the 3 years following diagnosis.

METHODOLOGY

Retrospective, multicenter, descriptive study based on a 3-year follow-up of patients diagnosed with HIV infection due to MTCT in 2018 in 10 hospitals in 8 Latin American countries (Costa Rica, Ecuador, Mexico, Honduras, El Salvador, Panama, Guatemala and Venezuela). The hospitals belonged to the PLANTAIDS network, which is included in CYTED (Ibero-American Programme of Science and Technology for Development).

RESULTS

The study population comprised 72 pediatric patients (38.9% male). The median age at diagnosis was 2.4 years (IQR: 0.8-5.4). There were 35 cases of opportunistic infections corresponding to 25 patients (34.7%), with tuberculosis being the most common. Adequate childhood vaccination coverage was achieved in 80.5%. There were 3 cases of acute SARS-CoV-2 infection, and these were asymptomatic or mildly symptomatic. According to the Centers for Disease Control and Prevention (CDC) classification, the most frequent clinical-immunological stage at all check-ups was C1. Three patients died from opportunistic infections and/or advanced HIV infection.

CONCLUSIONS

It is important to diagnose HIV infection early in pediatrics, since early initiation of ART is associated with a decrease in mortality. Despite this, HIV infection has a poor prognosis in children, necessitating adequate follow-up to ensure adherence to health care and ART, although it can sometimes prove difficult in children.

Measles seroprevalence in adolescents and young adults living with HIV and response to MMR booster in seronegative ones

OBJECTIVE

The study analyzed people with HIV (PWH) measles seroprevalence and response to MMR booster given to seronegative individuals.

DESIGN

A prospective cohort study with four groups: vertically (v-HIV), horizontally infected (h-HIV) individuals, and two control groups. An MMR booster was offered to seronegative individuals.

RESULTS

Measles seropositivity and IgG antibodies were significantly lower in v-HIV than in the other groups. All measles seronegative patients responded to booster.

CONCLUSION

An MMR booster must be sought during adolescence in vertically PWH.

Vaccination coverage and immunization safety among children with special health status in Chongqing, China

Vaccination of children with special health status has become one of the most urgent issues in China. We aim to evaluate vaccination coverage and safety as well as its associated factors among children with special health status in China during 2016‒2020. We conducted a retrospective cohort review of all children with special health status recorded in the Electronic Immunization Registries System in Chongqing, China, between 2016 and 2020. Univariate and multivariate logistic regression analyses were used to analyze the influence factors. Among the 2,175 children with special health status enrolled in the study, the overall vaccination coverage rate was lower than that among the general population, and the incidence of adverse event in them following immunization was very rare. Children with congenital heart disease were better vaccinated (aOR = 1.508-6.331), while most of the jaundice children had missed vaccination (aOR = 0.441‒0.556). The purchase of vaccine compensation insurance was associated with higher completion rate of basic immunization for Bacillus Calmette-G vaccine (aOR = 1.706, 95% CI: 1.249‒2.329) and rotavirus vaccine (aOR = 1.346, 95% CI: 1.061‒1.708). Children with special health status can be safely vaccinated. However, the vaccination coverage in these huge and vulnerable group is too low to protect them from vaccine-preventable diseases through immunization. More researches and interventions should be conducted to ensure a higher vaccination rate among the children with special health status.

Defective Monocyte Enzymatic Function and an Inhibitory Immune Phenotype in Human Immunodeficiency Virus-Exposed Uninfected African Infants in the Era of Antiretroviral Therapy

BACKGROUND

Human immunodeficiency virus-exposed uninfected (HEU) infants are a rapidly expanding population in sub-Saharan Africa and are highly susceptible to encapsulated bacterial disease in the first year of life. The mechanism of this increased risk is still poorly understood. We investigated whether human immunodeficiency virus (HIV)-exposure dysregulates HEU immunity, vaccine-antibody production, and human herpes virus amplify this effect.

METHODS

Thirty-four HIV-infected and 44 HIV-uninfected pregnant women were recruited into the birth cohort and observed up to 6 weeks of age; and then a subsequent 43 HIV-infected and 61 HIV-uninfected mother-infant pairs were recruited into a longitudinal infant cohort at either: 5-7 to 14-15; or 14-15 to 18-23 weeks of age. We compared monocyte function, innate and adaptive immune cell phenotype, and vaccine-induced antibody responses between HEU and HIV-unexposed uninfected (HU) infants.

RESULTS

We demonstrate (1) altered monocyte phagosomal function and B-cell subset homeostasis and (2) lower vaccine-induced anti-Haemophilus influenzae type b (Hib) and anti-tetanus toxoid immunoglobulin G titers in HEU compared with HU infants. Human herpes virus infection was similar between HEU and HU infants.

CONCLUSIONS

In the era of antiretroviral therapy-mediated viral suppression, HIV exposure may dysregulate monocyte and B-cell function, during the vulnerable period of immune maturation. This may contribute to the high rates of invasive bacterial disease and pneumonia in HEU infants.

Rubella antibodies in vertically and horizontally HIV-infected young adults vaccinated early in life and response to a booster dose in those with seronegative results

BACKGROUND

Very limited data are available on the persistence of rubella antibodies in vertically HIV-infected individuals who were vaccinated early in life.

METHODS

Prospective, cohort study on 4 groups of patients: 96 vertically HIV-1-infected individuals (v-HIV), 69 horizontally HIV-1-infected individuals (h-HIV), 93 healthy controls previously vaccinated for rubella (vac-CON) and 20 healthy controls with history of rubella disease (dis-CON). A blood sample was collected and rubella antibodies were analyzed by ELISA. Rubella antibodies above 10 IU/mL were considered protective. Individuals with seronegative results were offered an extra MMR vaccine dose and were tested at least 30 days afterwards.

RESULTS

Time since previous rubella vaccination was similar in v-HIV, h-HIV and vac-CON (16, 11 and 11 years; p = 0.428). v-HIV and h-HIV were also comparable regarding median CD4 T cells (613 and 614 cells/mm³; p = 0.599) and percentage on ART (93.8% and 98.6%; p = 0.135) at study entry. v-HIV had less individuals on virological suppression (63.5%) compared to 85.5% in h-HIV (p < 0.001). Rubella seropositivity and antibodies were significantly lower in v-HIV compared to h-HIV (32.3% vs 65.5%, 4.3 IU/mL vs 21.1 IU/mL; p < 0.001). Time interval between the last rubella vaccine dose and study entry was associated with an increase of rubella seronegativity, with a 7% higher chance of seronegativity for each one-year increase. After an extra MMR dose, 40 out of 48 (83.3%) seronegative individuals responded, with no significant difference among groups considering rubella seropositivity and antibody levels.

CONCLUSION

As vertically HIV-infected individuals reach adolescence and adulthood, assessment of vaccine antibodies can identify those who might benefit from an extra vaccine dose.

Protection of Vaccine Preventable Diseases in a Population of HIV-Infected Children: A 3 Years Prospective Study

Human Immunodeficiency Virus (HIV) infected children have a 30-70% chance of being incompletely immunized and may not respond serologically with the same magnitude or durability as uninfected children. The aim of the study was to describe the rate of protective antibodies titre and the persistence of the response against four recommended vaccinations in HIV infected children and adolescents. A two-phase observational study was performed in which protective IgG antibodies to measles, mumps, rubella and hepatitis B were determined and monitored for 12 and 24 months, in 26 perinatally HIV-infected children. The rate of protection for rubella and hepatitis B was significantly lower in the HIV group compared to the control group (92% vs. 65% for rubella and 78.4% vs. 45.4% for hepatitis B; p < 0.05). Children who received primary vaccination after initiating combination antiretroviral therapy (cART) had a higher rate of response. Seronegative patients who received a booster dose of vaccine had a good immunological response. HIV infection is associated with a lower response to vaccines against rubella and hepatitis. The beginning of cART before vaccination may be associated with a better response. The evaluation of the serological response is crucial in children with HIV infection in order to evaluate the protection of vaccine preventable diseases.

Gaps in knowledge about the vaccine coverage of immunocompromised children: a scoping review

Immunocompromised children are at increased risk of severe illness from vaccine-preventable infections. However, inadequate vaccine coverage remains a concern. This scoping review sought to determine the current state of knowledge regarding vaccine coverage of immunocompromised children. Bibliographic databases were searched for primary research from any year. Data were analyzed quantitatively and narratively. Ninety-seven studies met inclusion criteria. The most commonly studied vaccines were pneumococcal (n = 46), influenza (n = 44), diphtheria/tetanus/pertussis/poliomyelitis/Haemophilus influenzae type B/hepatitis B-containing (n = 36), and measles- and/or mumps- and/or rubella-containing (n = 29). Immunocompromising conditions studied included cancer/stem cell transplants (n = 24), solid organ transplants (n = 23), sickle cell disease (n = 21), immunosuppressive therapy (n = 14), human immunodeficiency virus (n = 12), splenectomy (n = 4), and primary immunodeficiency (n = 2). As more children are treated with immunosuppressive therapies, it is critical to identify whether they are being appropriately vaccinated for age and condition. We identified gaps in the current state of knowledge for specific vaccine types in specific immunocompromised populations.

Levels of vaccination coverage among HIV-exposed children in China: a retrospective study

Background

Vaccination is crucial for human immunodeficiency virus (HIV)-exposed children because of their increased risk of morbidity and mortality from various vaccine-preventable diseases. However, studies have shown that they are at high risk of incomplete vaccination. Although China has developed prevention of mother-to-child transmission (PMTCT) of HIV programs substantially over the past decades, few studies have investigated the immunization levels of Chinese HIV-exposed children. Therefore, we aimed to evaluate vaccination coverage and its associated factors among HIV-exposed children in China during 2016‒2018.

Methods

We conducted a retrospective cohort review of all cases of Chinese HIV-exposed children born between July 1, 2016 and June 30, 2018 recorded in the Chinese information system on PMTCT. The vaccination coverage indicators refer to the percentage of children who received recommended basic vaccines, including Bacillus Calmette-Guérin (BCG), hepatitis B (HepB), polio, measles-containing vaccine (MCV), and diphtheria-tetanus-pertussis-containing (DTP) vaccine. Univariate and multivariate logistic regression analyses expressed as crude odds ratios (cORs) and adjusted odds ratios (aORs), each with 95% confidence intervals (95% CI), were performed to compare the proportional differences of factors associated with vaccine coverage.

Results

Among the enrolled 10 033 children, the vaccination rate was 54.1% for BCG, 84.5% for complete HepB vaccination, 54.5% for complete polio vaccination, 51.3% for MCV, and 59.5% for complete DTP vaccination. Children with perinatally acquired HIV (PHIV) were 2.46‒3.82 times less likely to be vaccinated than HIV-exposed uninfected children. Multivariate logistic regression indicated that children of Han ethnicity (aOR = 1.33‒2.04), children with early infant diagnosis (EID) of HIV (aOR = 1.86‒3.17), and children whose mothers had better education (college or above, aOR = 1.63‒2.51) had higher odds of being vaccinated. Most of the deceased children (aOR = 4.28‒21.55) missed vaccination, and PHIV (aOR = 2.46‒3.82) significantly affected immunization.

Conclusions

Chinese HIV-exposed children had low vaccination coverage, which is a serious health challenge that needs to be addressed thoroughly. Interventions should be developed with a focus on minority HIV-exposed children whose mothers do not have formal education. Particularly, more attention should be paid to EID to increase access to immunization.

Graphical abstract

Correlates of Health Care Workers' Knowledge and HIV-Exposed Infant Immunization Counseling Practice in Northern Nigeria

BACKGROUND

Human Immunodeficiency Virus (HIV)-exposed and HIV-infected infants are at increased risk of vaccine-preventable diseases. However, little is known about health care workers' knowledge and immunization counseling practices in this population. We determined the predictors of health care workers' knowledge of vertical transmission risks, HIV exposed/infected infant immunization, and counseling practices in a tertiary center in Northern Nigeria.

METHODS

A cross-section of 297 health workers were interviewed using a structured, validated questionnaire. Knowledge and HIV-exposed infant immunization counseling practices were analyzed, and adjusted odds ratios for predictors were derived from logistic regression models.

RESULTS

Of the 297 participating health care workers, (32.3%, n=96) had adequate knowledge of HIV-exposed/infected infant immunization. Two-thirds (67%, n=199) of the participants appropriately identified the timing of infant diagnosis, while (73%, n=217) and (56.2%, n=167) correctly categorized infants as HIV-exposed and HIV-infected, respectively. Only (19.5%, n=58) participants had ever counselled a HIV-positive mother on infant immunization. Knowledge was predicted by work unit (HIV clinic vs. Obstetrics & Gynecology clinic), (Adjusted Odds Ratio (AOR) =3.78, 95% CI: 1.27-5.54), age (30-39 vs. <30 years), (AOR=2.24, 95% CI:1.19-5.67), years of experience (≥10 vs. <5), (AOR=1.76, 95% CI: 1.15-6.04), number of children (1 vs. 0), (AOR=1.73, 95% CI:1.14-4.23), infant immunization training (yes vs. no), (AOR=1.57, 95% CI:1.12-5.43), female sex (AOR = 1.17, 95% CI:1.06-2.21), profession (nurse/midwife vs. physician), (AOR=0.44, 95% CI:0.21-0.94) and previous HIV test (no vs. yes), (AOR=0.67, 95% CI:0.21-0.83).

CONCLUSION AND GLOBAL HEALTH IMPLICATIONS

Knowledge of HIV-exposed infant immunization was low and counseling practices were sub-optimal. Both immunization knowledge and counseling practices were predicted by demographic, professional, and training variables. Our findings indicate the need for educating health care workers on HIV exposed/infected infant immunization policy and improving counseling skills through capacity-building programs.

Measles Immunity at 4.5 Years of Age Following Vaccination at 9 and 15-18 Months of Age Among Human Immunodeficiency Virus (HIV)-infected, HIV-exposed-uninfected, and HIV-unexposed Children

BACKGROUND

Human immunodeficiency virus (HIV)-infected and HIV-exposed-uninfected (HEU) children may be at increased risk of measles infection due to waning of immunity following vaccination. We evaluated persistence of antibodies to measles vaccination at 4.5 years of age in HIV-unexposed, HEU, and HIV-infected children with CD4+ ≥25% previously randomized to immediate antiretroviral therapy (ART) interrupted at 12 months (HIV/Immed-ART-12), 24 months (HIV/Immed-ART-24), or when clinically/immunologically indicated (HIV/Def-ART). The HIV/Def-ART group initiated ART by median 5.8 (interquartile range, 4.4-10.3) months of age.

METHODS

In this study, HIV-unexposed (n = 95), HEU (n = 84), HIV/Immed-ART-12 (n = 70), HIV/Immed-ART-24 (n = 70), and HIV/Def-ART (n = 62) children were scheduled to receive measles vaccination at age 9 and 15-18 months. Antimeasles serum immunoglobulin G titers were quantified using enzyme-linked immunosorbent assay at 4.5 years.

RESULTS

Compared with HIV-unexposed children (2860 mIU/mL), measles antibody geometric mean titers (GMTs) were significantly lower in both HIV/Immed-ART-12 (571; P < .001) and HIV/Immed-ART-24 (1136; P < .001) but similar in the HIV/Def-ART (2777) and HEU (3242) groups. Furthermore, compared with HIV-unexposed, antibody titers ≥330 mIU/mL (ie, presumed serocorrelate for protection; 99%) were also significantly lower in HIV/Immed-ART-12 (70%; P < .001) and HIV/Immed-ART-24 (83%; P < .001) but similar in the HIV/Def-ART (90%) and HEU (98%) groups.

CONCLUSIONS

HIV-infected children in whom ART was interrupted at either 12 or 24 months had lower GMTs and lower proportions with seroprotective titers than HIV-unexposed children, indicating a potential downside of ART treatment interruption.

CLINICAL TRIALS REGISTRATION

NCT00099658 and NCT00102960.

Immune response to a Tdap booster in vertically HIV-infected adolescents

BACKGROUND

Pertussis cases have increased worldwide and knowledge on immune response and cytokine profile after Tdap vaccine in immunodeficient adolescents is scarce.

OBJECTIVE

To evaluate the immune response after Tdap in HIV-infected (HIV) and in healthy adolescents (CONTROL).

METHODOLOGY

Thirty HIV adolescents with CD4 cell counts >200 and 30 CONTROLs were immunized with Tdap, after a prior whole-cell DTP vaccine primary scheme. Blood samples were collected immediately before and after vaccine. Lymphocyte immunophenotyping was performed by flow cytometry; tetanus, diphtheria and pertussis toxin antibodies were assessed by ELISA; whole blood was stimulated with tetanus toxoid and Bordetella pertussis and supernatants were assessed for cytokines by xMAP.

RESULTS

Mean age of HIV and CONTROL groups were 17.9 e 17.1 years, respectively. Pain at injection site was more intense in CONTROL group. HIV group had similar increase in tetanus antibodies at 28 days (geometric mean concentration, GMC, 15.6; 95% CI, 7.52-32.4) than CONTROL group (GMC, 23.1; 95% CI, 15.0-35.5), but lower diphtheria antibodies at 28 days (GMC, 2.3; 95% CI, 0.88-6.19) than CONTROL group (GMC, 16.4; 95% CI, 10.3-26.2); for pertussis, the percentage of individuals who seroconverted was lower in HIV than CONTROL group (HIV, 62.1% versus CONTROL, 100%; p = .002). Both groups built a cellular immune response to tetanus, with a Th2 (IL-4, IL-5 and IL-13) and Th1 (IFN-γ) response, with lower cytokine levels in HIV than in CONTROL group. Especially for pertussis, cellular and humoral responses were less intense in HIV adolescents, with a lower Th1 and Th17 profile and higher IL-10 levels. HIV-infected adolescents on viral suppression showed an enhanced immune response to all the three vaccine antigens, although still at lower levels if compared to CONTROL group.

CONCLUSIONS

Both groups tolerated well and built an immune response after Tdap. However, HIV-infected adolescents would probably benefit from more frequent booster doses.

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.