Immunogenicity of a monovalent 2009 influenza A (H1N1) vaccine in an immunocompromised population: a prospective study comparing HIV-infected adults with HIV-uninfected adults

Comparative immunogenicity and neutralizing antibody responses post heterologous vaccination with CoronaVac (Sinovac) and Vaxzevria (AstraZeneca) in HIV-infected patients with varying CD4+ T lymphocyte counts

The immune response to heterologous coronavirus disease (COVID-19) vaccination in people living with HIV (PLWH) is still unclear. Herein, our prospective cohort study aimed to compare the immune response of heterologous vaccination with CoronaVac (Sinovac) and Vaxzevria (AstraZeneca) between PLWH having CD4 counts ≤ 200 cells/µL (low CD4+) and > 200 cells/µL (high CD4+). Anti-receptor-binding domain (RBD) immunoglobulin G (IgG) levels and the percentage inhibition of neutralizing antibodies (nAbs) were analyzed at 2 and 12 weeks after immunization. Participants in the low and high CD4+ groups had mean CD4+ counts of 139 and 575 cell/µL, respectively. Two and 12 weeks after immunization, in the low CD4 group, the median anti-RBD-IgG levels were 159 IU/mL and 143 IU/mL, respectively, whereas the nAb level was 71% and decreased to 47.2%, respectively. Contrarily, the median anti-RBD-IgG levels in the high CD4+ group were 273 IU/mL and 294 IU/mL, respectively, whereas the nAb levels were 89.3% and relatively stable at 81.6%. However, although immune responses between the two study groups were not significantly different, a decline in nAb levels was observed at 12 weeks in the low CD4+ group. Therefore, a COVID-19 booster vaccine dose is suggested for immunoprotection.

Longevity of serologic responses following a single dose of typhoid conjugate vaccine among children living with HIV in Pakistan: A prospective cohort study

BACKGROUND

This study aimed to assess the longevity of serologic response and seroconversion rates at several time points following TCV vaccination among children living with HIV aged 6 months to 15 years in Pakistan.

METHODS

From November 20, 2020, to January 2, 2021; 336 children were enrolled and followed up prospectively for 12 months. Blood samples were collected before the administration of TCV and at 4-6 weeks, 6 months, and 1 year after administration of a single dose (0.5 ml) of intramuscular Typbar TCV®. Samples were analyzed for anti-Vi-IgG antibodies using ELISA. Geometric mean titers (GMTs), seroconversion rates (fourfold rise in anti-Vi-IgG from baseline) were assessed, and factors associated with sustained seroconversion at 1 year were evaluated using generalized linear mixed models.

FINDINGS

The seroconversion rates were significantly lower in children aged 6 months to 5 years compared to children > 5 years; (127/216 (58·8%)) versus (81/111 (73·0%)) at 6 months and (110/217 (50·7%)) versus (78/109 (71·6%)) at 1 year, only two-third; 188/326 (57·7%) remained seroconverted at 1 year. The GMTs (95 % CI) were significantly lower in children aged 6 months to 5 years compared to children > 5 years, 9·6 (7·6, 12·0) versus 28·9 (20·2, 41·4) at 6 months, and 6·6 (5·4, 8·0) versus 23·1 (16·4, 32·5) at 1 year time point. The odds of sustained seroconversion significantly decreased with time (adjusted odds ratio (aOR): 0.23; 95 % CI: 0.14, 0.40). The odds of sustained seroconversion following 1 year of TCV vaccination were significantly higher among children with non-severe HIV clinical disease (aOR: 10·61; 95% CI: 1·52, 73·98) and children in elder age group (aOR: 7·45; 95% CI: 1·18, 47·03).

CONCLUSIONS

A significant decrease in seroconversion rates was observed among children living with HIV following one year of TCV administration. The decline was significantly higher in children with severe or advanced HIV clinical disease and children younger than five years of age.

Burden of Vaccine-Preventable Diseases in People Living with HIV

Vaccine-preventable diseases (VPDs) pose a serious public health concern for people living with HIV (PLH). PLH experience a delayed and weakened response to many vaccines available, compared to the general population. Lower seroconversion rates, along with a decreased efficacy and durability of vaccines, increases the susceptibility of PLH to VPDs. Vaccination guidelines specifically targeting this population have been modified to overcome these challenges. However, vaccine uptake remains suboptimal due to multiple barriers, highlighting the need for further studies and the additional implementation of public health measures specifically tailored to PLH.

Humoral immune response following the inactivated quadrivalent influenza vaccination among HIV-infected and HIV-uninfected adults

BACKGROUND

A limited amount of information is available about the immunogenicity of the quadrivalent inactivated influenza vaccine among human immunodeficiency virus (HIV)-infected individuals, especially in low and middle-income countries (LMICs).

METHODS

HIV-infected adults and HIV-uninfected adults received a dose of quadrivalent inactivated influenza vaccine including strains of H1N1, H3N2, BV and BY. Enzyme-linked immunosorbent assay (ELISA) and hemagglutination-inhibition assay (HAI) were used to determine IgA, IgG antibody concentration and geometric mean titers (GMT) at day 0 and day 28, respectively. Associated factors contributing to seroconversion or GMT changes were analyzed using simple logistic regression model.

RESULTS

A total of 131 HIV-infected and 55 HIV-uninfected subjects were included in the study. In both HIV-infected and uninfected arms, IgG and IgA against influenza A and B all increased significantly at day 28 after receiving QIV (P < 0.001). GMTs of post-vaccination at day 28 showed that HIV-infected persons with CD4 + T cell counts ≤ 350 cells/mm3 were statistically less immunogenic to all strains of QIV than HIV-uninfected ones (P < 0.05). HIV-infected participants with CD4 + T cell counts ≤ 350 cells/mm3 were less likely to achieve seroconversion to QIV (H1N1, BY and BV) than HIV-uninfected individuals at day 28 after vaccination (P < 0.05). Compared with HIV-infected patients with baseline CD4 + T cell counts ≤ 350 cells/mm3, individuals with baseline CD4 + T cell counts > 350 cell/mm3 seemed more likely to generate antibody responses to H1N1 (OR:2.65, 95 %CI: 1.07-6.56) and BY (OR: 3.43, 95 %CI: 1.37-8.63), and showed a higher probability of seroconversion to BY (OR: 3.59, 95 %CI: 1.03-12.48). Compared with nadir CD4 + T cell count ≤ 350 cell/mm3, individuals with nadir CD4 + T cell count > 350 cell/mm3 showed a higher probability of seroconversion to H1N1(OR: 3.15, 95 %CI: 1.14-8.73).

CONCLUSION

Influenza vaccination of HIV-infected adults might be effective despite variable antibody responses. HIV-positive populations with CD4 + T cell counts ≤ 350 are less likely to achieve seroconversion. Further vaccination strategies could be developed for those with low CD4 T cell counts.

Human lymph node immune dynamics as driver of vaccine efficacy: an understudied aspect of immune responses

INTRODUCTION

During the last century, changes in hygiene, sanitation, and the advent of childhood vaccination have resulted in profound reductions in mortality from infectious diseases. Despite this success, infectious diseases remain an enigmatic public health threat, where effective vaccines for influenza, human immunodeficiency virus (HIV), tuberculosis, and malaria, among others remain elusive.

AREA COVERED

In addition to the immune evasion tactics employed by complex pathogens, our understanding of immunopathogenesis and the development of effective vaccines is also complexified by the inherent variability of human immune responses. Lymph nodes (LNs) are the anatomical sites where B cell responses develop. An important, but understudied component of immune response complexity is variation in LN immune dynamics and in particular variation in germinal center follicular helper T cells (Tfh) and B cells which can be impacted by genetic variation, aging, the microbiome and chronic infection.

EXPERT OPINION

This review describes the contribution of genetic variation, aging, microbiome and chronic infection on LN immune dynamics and associated Tfh responses and offers perspective on how inclusion of LN immune subset and cytoarchitecture analyses, along with peripheral blood biomarkers can supplement systems vaccinology or immunology approaches for the development of vaccines or other interventions to prevent infectious diseases.

Seasonal trivalent inactivated influenza vaccine with topical imiquimod in immunocompromised patients: A randomized controlled trial

BACKGROUND

The effect of the Toll-like receptor 7 agonist imiquimod before intradermal (ID) or intramuscular (IM) influenza vaccine in immunocompromised hosts is unknown.

METHODS

In this open-label randomized controlled trial, kidney transplant recipients (KT) and people living with HIV (PLWH) were randomized to receive IM trivalent inactivated influenza vaccine alone (IM), IM vaccine after topical imiquimod (imi+IM) or ID vaccine after topical imiquimod (imi+ID). Immunogenicity was assessed by hemagglutination inhibition assay. The primary outcome was vaccine response, defined as seroconversion to at least one viral strain at day 21.

RESULTS

Seventy patients (35 KT and 35 PLWH) received IM (24), imi+IM (22), or imi+ID (24) vaccine. Vaccine response was 61% (14/23) with IM, 59% (13/22) with imi+IM, and 65% (15/23) with imi+ID vaccine (P = 0.909). Vaccine response was associated with HIV infection compared to kidney transplantation (adjusted-OR 3.74, 95% CI 1.25 - 11.23, P = 0.019), but not with imiquimod application nor ID injection. After vaccination, seroprotection to all viral strains was 79% (19/24) with IM, 68% (15/22) with imi+IM, and 70% (16/23) with imi+ID (P = 0.657). We did not observe any vaccine-related severe adverse event.

CONCLUSIONS

In our study, topical imiquimod did not improve the immunogenicity of influenza vaccine in KT and in PLWH.

Vaccine responses in ageing and chronic viral infection

Over the last few decades, changing population demographics have shown that there are a growing number of individuals living past the age of 60. With this expanding older population comes an increase in individuals that are more susceptible to chronic illness and disease. An important part of maintaining health in this population is through prophylactic vaccination, however, there is growing evidence that vaccines may be less effective in the elderly. Furthermore, with the success of anti-viral therapies, chronic infections such as HIV are becoming increasingly prevalent in older populations and present a relatively unstudied population with respect to the efficacy of vaccination. Here we will examine the evidence for age-associated reduction in antibody and cellular responsiveness to a variety of common vaccines and investigate the underlying causes attributed to this phenomenon, such as inflammation and senescence. We will also discuss the impact of chronic viral infections on immune responses in both young and elderly patients, particularly those living with HIV, and how this affects vaccinations in these populations.

Residual immune dysfunction under antiretroviral therapy

The usage of combination antiretroviral therapy in people with HIV (PWH) has incited profound improvement in morbidity and mortality. Yet, PWH may not experience full restoration of immune function which can manifest with non-AIDS comorbidities that frequently associate with residual inflammation and can imperil quality of life or longevity. In this review, we discuss the pathogenesis underlying chronic inflammation and residual immune dysfunction in PWH, as well as potential therapeutic interventions to ameliorate them and prevent incidence or progression of non-AIDS comorbidities. Current evidence advocates that early diagnosis and prompt initiation of therapy at high CD4 counts may represent the best available approach for an improved immune recovery in PWH.

Impact of Maternal HIV Infection and Placental Malaria on the Transplacental Transfer of Influenza Antibodies in Mother-Infant Pairs in Malawi, 2013-2014

BACKGROUND

Maternal influenza vaccination protects infants against influenza virus infection. Impaired transplacental transfer of influenza antibodies may reduce this protection.

METHODS

We conducted a cross-sectional study of influenza vaccine-naïve pregnant women recruited at delivery from Blantyre (urban, low malaria transmission) and Chikwawa (rural, high malaria transmission) in Southern Malawi. HIV-infected mothers were excluded in Chikwawa. Maternal and cord blood antibodies against circulating influenza strains A/California/7/2009, A/Victoria/361/2011, B/Brisbane/60/2008, and B/Wisconsin/1/2010 were measured by hemagglutination inhibition (HAI). We studied the impact of maternal HIV infection and placental malaria on influenza antibody levels in mother-infant pairs in Blantyre and Chikwawa, respectively.

RESULTS

We included 454 mother-infant pairs (Blantyre, n = 253; Chikwawa, n = 201). HIV-infected mothers and their infants had lower seropositivity (HAI titer ≥1:40) against influenza A(H1N1)pdm09 (mothers, 24.3 vs 45.4%; P = .02; infants, 24.3 vs 50.5%; P = .003) and A(H3N2) (mothers, 37.8% vs 63.9%; P = .003; infants, 43.2 vs 64.8%; P = .01), whereas placental malaria had an inconsistent effect on maternal and infant seropositivity. In multivariable analyses, maternal HIV infection was associated with reduced infant seropositivity (A(H1N1)pdm09: adjusted odds ratio [aOR], 0.34; 95% confidence interval [CI], 0.15-0.79; A(H3N2): aOR, 0.43; 95% CI, 0.21-0.89). Transplacental transfer was not impaired by maternal HIV or placental malaria.

CONCLUSIONS

Maternal HIV infection influenced maternal antibody response to influenza A virus infection, and thereby antibody levels in newborns, but did not affect transplacental antibody transfer.

Standard-Dose Intradermal Influenza Vaccine Elicits Cellular Immune Responses Similar to Those of Intramuscular Vaccine in Men With and Those Without HIV Infection

BACKGROUND

Human immunodeficiency virus (HIV)-infected persons are at a higher risk of severe influenza. Although we have shown that a standard-dose intradermal influenza vaccine versus a standard-dose intramuscular influenza vaccine does not result in differences in hemagglutination-inhibition titers in this population, a comprehensive examination of cell-mediated immune responses remains lacking.

METHODS

Serological, antigen-specific B-cell, and interleukin 2-, interferon γ-, and tumor necrosis factor α-secreting T-cell responses were assessed in 79 HIV-infected men and 79 HIV-uninfected men.

RESULTS

The route of vaccination did not affect the immunoglobulin A and immunoglobulin G (IgG) plasmablast or memory B-cell response, although these were severely impaired in the group with a CD4+ T-cell count of <200 cells/μL. The frequencies of IgG memory B cells measured on day 28 after vaccination were highest in the HIV-uninfected group, followed by the group with a CD4+ T-cell count of ≥200 cells/μL and the group with a CD4+ T-cell count of <200 cells/μL. The route of vaccination did not affect the CD4+ or CD8+ T-cell responses measured at various times after vaccination.

CONCLUSIONS

The route of vaccination had no effect on antibody responses, antibody avidity, T-cell responses, or B-cell responses in HIV-infected or HIV-uninfected subjects. With the serological and cellular immune responses to influenza vaccination being impaired in HIV-infected individuals with a CD4+ T-cell count of <200 cells/μL, passive immunization strategies need to be explored to protect this population.

CLINICAL TRIALS REGISTRATION

NCT01538940.

Neutralization and hemagglutination-inhibition antibodies following influenza vaccination of HIV-infected and HIV-uninfected pregnant women

Background

We previously reported that despite HIV-infected pregnant women had modest humoral immune responses to inactivated influenza vaccine (IIV) measured by hemagglutination-inhibition (HAI) assay, the observed vaccine efficacy against influenza disease was higher than predicted by HAI; suggesting that IIV may confer protection to HIV-infected individuals by additional mechanisms. We evaluated the response to IIV by microneutralization (MN) and HAI assays and correlated both methods in HIV-infected and HIV-uninfected pregnant women.

Methods

MN and HAI antibodies were measured pre-vaccination and approximately one-month post-vaccination in 80 HIV-infected and 75 HIV-uninfected women who received IIV. Geometric mean titers (GMTs), fold-change in titers and seroconversion rates were determined for the three influenza stains in the vaccine.

Results

After vaccination there were significant increases in MN and HAI GMTs for the three vaccine strains in both HIV-infected and HIV-uninfected women. HIV-infected women had, however, a lower immune response compared to HIV-uninfected. Fold-increases were 2 to 3-times higher for MN assay compared to HAI assay for the influenza-A strains. Also a higher percentage of women seroconverted by MN than by HAI assay for the influenza-A strains. There was high positive correlation between MN and HAI assays, except for the B/Victoria strain at pre-vaccination.

Conclusions

In general, the MN assay was more sensitive than the HAI assay. Microneutralization antibodies might correlate better with protection against influenza infection.

Influence of sample collection tube method, anticoagulant-containing plasma versus serum, on influenza virus hemagglutination inhibition titer and microneutralization titer serological assays

BACKGROUND

The hemagglutination-inhibition (HAI) assay is a critical component for measurement of immunogenicity in influenza vaccine development. It is unknown if the results can be influenced by sample type and anticoagulants. The purpose of this study was to evaluate the influence of different sample collection methods, in particular different anticoagulants, and choice of plasma or serum, on influenza virus serological assays.

METHODS

Blood samples from thirty donors previously immunized against influenza viruses were collected using six different types of blood collection tubes, two of which collect serum and four of which contain various anticoagulants for collecting plasma. Serum: (1) serum separator tubes (SST); and (2) Plus Plastic serum "red-top serum" tubes. Plasma: (3) spray-coated K2 ethylenediaminetetraacetic acid (EDTA) tubes: (4) Sodium Heparin tubes; (5) Citrate tubes with 3.2% sodium citrate solution; and (6) Glass Blood Collection tubes with acid citrate dextrose. Samples were tested against three different influenza viruses (A/California/07/2009 (H1N1pdm09), A/Texas/50/2012 (H3N2), and B/Massachusetts/2/2012) for hemagglutination inhibition titer and virus neutralization titer via a microneutralization (MN) assay, and data compared to that obtained for standard serum sample collected in SST.

RESULTS

HAI and MN titers against type A viruses were within two dilutions compared to SST collection method over 96% of the time irrespective of sample type or anticoagulant. However, HAI titers for type B virus were more variable across different collection methods. EDTA plasma samples were greater than two dilutions higher than SST serum samples 70% (21 of 30 samples) of the time. In contrast, MN titers were within two dilutions over 96% of the time, with the highest deviation noted in acid citrate dextrose plasma samples (3 of 30 samples tested, 10%).

CONCLUSIONS

These data provide useful guidelines for sample collection and serology testing when screening: (i) influenza vaccine immunogenicity antibody response; (ii) antibody responses to newly emerging viral strains; and (iii) clinical samples for anti-influenza antibody activity.

Evaluation of T and B memory cell responses elicited by the pandemic H1N1 vaccine in HIV-infected and HIV-uninfected individuals

BACKGROUND

This study was to compare B and T memory cells elicited by a single dose monovalent 2009 influenza A (H1N1) vaccine (strain A/California/7/2009 H1N1) in HIV⁺ and HIV^- groups, and to analyze the impact of the prior seasonal vaccines to the immunogenicity of this vaccine.

METHODS

Blood samples were collected before vaccination (day 0) and at days 28 and 180. Participants were categorized into HIV^-/LAIV, HIV^-/TIV and HIV⁺/TIV subgroups according to the trivalent live-attenuated or inactivated (LAIV or TIV) seasonal influenza vaccines they received previously. The IgG⁺ memory B cells (B_Mem) and IFNγ⁺ T cells were measured against antigens including the H1N1 vaccine, the hemagglutinin (HA) and neuraminidase (NA) proteins or peptide pools of the pandemic and the seasonal H1N1 strains, respectively.

RESULTS

Overall B_Mem responses increased significantly at day 28 but returned to baseline by day 180 in all three subgroups. The average frequency of the H1N1-specific B_Mem at day 28 for the HIV^-/LAIV, HIV^-/TIV and HIV⁺/TIV groups was 2.14%, 1.26% and 1.67%, respectively, and the average fold change was 14.39, 3.81 and 3.93, respectively. The differences of B_Mem between HIV^-/LAIV and the two TIV subgroups were significant. For the IFNγ response, the overall spot counts ranged widely between 0 and 958/10⁶ PBMCs. The group average spot counts to H1N1 vaccine was 89, 102, and 30 at day 28 for HIV^-/LAIV, HIV^-/TIV and HIV⁺/TIV subgroups, respectively. The average increase of IFNγ response at day 28 vs day 0 in all three subgroups did not reach 2-fold.

CONCLUSION

Participants with a prior LAIV seasonal vaccine, as compared to a TIV seasonal vaccine, responded significantly better to the monovalent H1N1 vaccine. Excluding LAIV participants, no difference was seen between the HIV⁺ and HIV^- subject groups in terms of B_Mem. The B_Mem response declined at 6months.

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

Vaccination is a critical component for ensuring the health of those living with the human immunodeficiency virus (HIV) by protection against vaccine-preventable diseases. Since HIV-infected persons may have reduced immune responses and shorter durations of protection post-vaccination, HIV-specific guidelines have been published by global and national advisory organizations to address these potential concerns. This article provides a comprehensive review of the current guidelines and evidence-based data for vaccinating HIV-infected adults, including guidance on modified vaccine dosing and testing strategies, as well as safety considerations, to enhance protection among this vulnerable population. In the current article, part I of the two-part series, inactivated vaccines with broad indications as well as vaccines for specific risk and age groups will be discussed.

Vaccination of HIV-infected pregnant women: implications for protection of their young infants

Background

The prevention of mother to child transmission of HIV has resulted in reduced burden of pediatric HIV-infection, but the prevalence of maternal HIV infection remains high in sub-Saharan African countries. HIV-exposed-uninfected infants have an increased risk of morbidity and mortality due to infectious diseases than HIV-unexposed infants, particularly during the first six months of life, which in part might be due to lower levels of pathogen-specific protective antibodies acquired transplacentally from their mothers. This could be mitigated by vaccinating pregnant women to boost antibody levels; although vaccine responses among HIV-infected pregnant women might differ compared to HIV-uninfected women. We reviewed studies that compared natural and vaccine-induced antibody levels to different epitopes between HIV-infected and HIV-uninfected pregnant women.

Findings

Most studies reported lower baseline/pre-vaccination antibody levels in HIV-infected pregnant women, which may not be reversed by antiretroviral therapy during pregnancy. There were only few studies on vaccination of HIV-infected pregnant women, mainly on influenza virus and group B Streptococcus (GBS) vaccines. Immunogenicity studies on influenza vaccines indicated that HIV-infected pregnant women had lower vaccine induced hemagglutination inhibition antibody titers and a decreased likelihood of seroconversion compared to HIV-uninfected women; and while higher CD4+ T-lymphocyte levels were associated with better immune responses to vaccination, HIV viral load was not associated with responses. Furthermore, infants born to influenza vaccinated HIV-infected pregnant women also had lower antibody levels and a lower proportion of HIV-exposed infants had titers above the putative correlate of protection compared to HIV-unexposed infants. The immunogenicity of a CRM₁₉₇-conjugated trivalent GBS vaccine was also lower in HIV-infected pregnant women compared to HIV-uninfected women, irrespective of CD4+ T-lymphocyte counts.

Conclusions

Poorer immunogenicity of vaccines reported in HIV-infected compared to HIV-uninfected pregnant women might compromise the potential benefits to their young infants. Alternate vaccination strategies, including vaccines with higher antigen concentration, adjuvanted vaccines or multiple doses schedules might be required in HIV-infected pregnant women to optimize antibody transferred to their fetuses.

Safety and immunogenicity of influenza vaccine among HIV-infected adults: Conventional vaccine vs. intradermal vaccine

Several studies have reported poor immune responses to conventional influenza vaccines in HIV-infected individuals. This study sought to elicit more potent immunogenicity in HIV-infected adults using an intradermal vaccine compared with a conventional intramuscular vaccine. This multicenter, randomized, controlled, open-label study was conducted at 3 university hospitals during the 2011/2012 pre-influenza season. Three vaccines were used in HIV-infected adults aged 18 - 60 years: an inactivated intramuscular vaccine (Agrippal), a reduced-content intradermal vaccine (IDflu9μg) and a standard-content intradermal vaccine (IDflu15μg). Serum hemagglutination-inhibiting (HI) antibodies and INF-γ ELISpot assay were measured at the time of vaccination and 1 month after vaccination. Adverse events were recorded for 7 d. A total of 28 Agrippal, 30 IDflu9μg, and 28 IDflu15μg volunteers were included in this analysis. One month after vaccination, the GMTs and differences in INF-γ ELISpot assay results were similar among the 3 groups. Seroprotection rates, seroconversion rates and mean fold increases (MFI) among the 3 groups were also similar, at approximately 80%, 50-60% and 2.5 - 10.0, respectively. All three vaccines satisfied the CHMP criteria for the A/H1N1 and A/H3N2 strains, but not those for the B strain. In univariate analysis, no demographic or clinical factors, including age, CD4+ T-cell counts, HIV viral load, ART status and vaccine type, were related to failure to achieve seroprotection. The three vaccines were all well-tolerated and all reported reactions were mild to moderate. However, there was a tendency toward a higher incidence of local and systemic reactions in the intradermal vaccine groups. The intradermal vaccine did not result in higher immunogenicity compared to the conventional intramuscular vaccine, even with increased antigen dose.

Fluzone® High-Dose Influenza Vaccine

INTRODUCTION

Fluzone® High-Dose (IIV3-HD) is a trivalent, inactivated, split-virus influenza vaccine indicated for use in older adults (≥65 years of age). It contains 60 µg hemagglutinin of each influenza strain, which is four times the hemagglutinin content of standard-dose influenza vaccines, including Fluzone (IIV3-SD). IIV3-HD has been licensed for use in older adults in the US since December 2009 and in Canada since February 2016. Areas covered: In this review, we summarize postlicensure studies on the immunogenicity, safety, and effectiveness of IIV3-HD and estimates of its cost-effectiveness in older adults. We also discuss the potential application of IIV3-HD in adults 50-64 years of age and in individuals who may respond poorly to standard-dose influenza vaccines. Expert commentary: Multiple studies conducted since 2004 have consistently shown that, in older adults, IIV3-HD induces substantially greater antibody responses and better protection against influenza and influenza-associated hospitalization than IIV3-SD. Health economic analyses suggest that IIV3-HD can be a cost-effective alternative to standard-dose trivalent or quadrivalent inactivated influenza vaccines and can even be cost-saving compared to IIV3-SD in older adults. Further investigation of IIV3-HD vaccination as a way to improve immune responses and protection against influenza in immunocompromised individuals is warranted.

Vitamin D levels and influenza vaccine immunogenicity among HIV-infected and HIV-uninfected adults

BACKGROUND

Vaccination is the most important preventive strategy against influenza, however post-vaccination antibody responses are often inadequate especially among HIV-infected persons. Vitamin D deficiency has been suggested to adversely influence immune responses and is highly prevalent among HIV-infected adults. Therefore, we evaluated the association between 25-hydroxyvitamin D [25(OH)D] levels and post-influenza vaccination responses.

METHODS

We conducted a prospective cohort study evaluating the immunogenicity of monovalent influenza A (H1N1) vaccination among both HIV-infected and HIV-uninfected adults (18-50years of age) during the 2009-2010 influenza season. Antibody titers were evaluated at baseline, day 28, and 6months post-vaccination using hemagluttination inhibition assays. Serum 25(OH)D levels were measured at day 28. Univariate and multivariate regression analyses examined the association between 25(OH)D levels [categorized as <20ng/ml (deficiency) vs. ⩾20ng/ml] with the primary outcome of seroconversion. Secondary outcomes included seroprotection; a ⩾4-fold increase in titers; and geometric mean titers post-vaccination. Analyses were repeated using 25(OH)D levels as a continuous variable.

RESULTS

A total of 128 adults [64 HIV-infected (median CD4 count 580cells/mm(3)) and 64 HIV-uninfected] were included. Seroconversion at day 28 post-vaccination was achieved in fewer HIV-infected participants compared with HIV-uninfected participants (56% vs. 74%, p=0.03). Vitamin D deficiency was more prevalent among HIV-infected persons vs. HIV-uninfected persons (25% vs. 17%), although not significantly different (p=0.39). There were no associations found between lower 25(OH)D levels and poorer antibody responses at day 28 or 6months for any of the study outcomes among either HIV-infected or HIV-uninfected adults.

CONCLUSION

Vitamin D deficiency was common among both HIV-infected and HIV-uninfected adults, but lower levels did not predict antibody responses after H1N1 (2009) influenza vaccination. Low 25(OH)D levels do not explain poorer post-vaccination responses among HIV-infected persons.

Comparison of different collection methods for reported adverse events following pandemic and seasonal influenza vaccination

BACKGROUND

During the 2009/2010 season, information on adverse events after administration of seasonal and pandemic influenza vaccines was collected by different active surveys in the Netherlands. In the present paper, we compared data from a paper-based questionnaire with data from a web-based questionnaire with respect to outcomes and target population, in order to guide future influenza vaccine safety monitoring.

METHODS

The paper-based survey collected data from patients who attended primary care practices in the province of Utrecht for influenza vaccination. The web-based survey recruited participants from the general population all provinces of the Netherlands. To analyze the association between study approach and the reported local and systemic adverse events, a generalized estimation equation model was applied. We adjusted for age, gender, comorbidity, previous vaccination and socio-economic status score.

RESULTS

No significant differences were found between the two studies approaches in reporting local reactions (OR: 0.98, 95% CI 0.88-1.10) and systemic AEs (OR: 1.12, 95% CI 0.99-1.27). There were important differences in the age groups that responded. The elderly were more represented in the paper-based survey where participants were recruited via GPs (79%⩾60years) compared to 37% in the web-based survey where participants were recruited via internet.

CONCLUSION

The paper-based survey with recruitment of participants through GPs is more representative for the target group of influenza vaccination compared to the web-based survey with recruitment of participants via internet. A web-based approach with recruitment of participants via internet seems more suitable for situations where information about adverse events on a national level is desirable. We recommend to recruit participants for a web-based survey during mass vaccinations sessions by GPs to comply with the recommendations of the European Centre for Disease Prevention Control.

Randomized Controlled Trial to Compare Immunogenicity of Standard-Dose Intramuscular Versus Intradermal Trivalent Inactivated Influenza Vaccine in HIV-Infected Men Who Have Sex With Men in Bangkok, Thailand

BACKGROUND

Individuals infected with human immunodeficiency virus (HIV) are at increased risk for severe influenza, yet immune responses to standard-dose intramuscular (IM) influenza vaccine are suboptimal in this population. Intradermal (ID) delivery of influenza vaccine might improve immune response through enhanced stimulation of dendritic cells.

METHODS

We conducted a randomized, double-blind, controlled trial to compare the immunogenicity of off-label standard-dose (15 µg) ID vs standard-dose (15 µg) IM inactive influenza vaccine in HIV-infected men in Bangkok, Thailand. The primary study outcome was seroconversion (minimum titer of 1:40 and ≥4-fold rise in antibody titer) at 1 month postvaccination based on serum hemagglutination inhibition antibody titers against each vaccine strain. Adverse events (AEs) in the 7 days following vaccination were also assessed.

RESULTS

We enrolled 400 HIV-infected participants; 200 were randomly assigned to receive IM and 200 ID vaccine. Vaccine arms were well-balanced with respect to age, CD4 cell count, HIV RNA load, and antiretroviral treatment. Percentage of seroconversion to all (ID 14% vs IM 15%; P = .8) or at least 1 (ID 69% vs IM 68%; P = .7) of the 3 vaccine strains did not differ significantly between ID vs IM vaccine recipients. A higher proportion of participants who received ID vaccine had mild injection-site AEs compared with participants who received IM vaccine (77% vs 27%).

CONCLUSIONS

There were no significant differences in the immunogenicity of standard-dose ID vs IM influenza vaccine in this HIV-infected population in Thailand. Additional strategies to enhance immune responses to influenza vaccine among HIV-infected persons are needed.

CLINICAL TRIALS REGISTRATION

NCT01538940.

Association of CMV, HBV, or HCV co-infection with vaccine response in adults with well-controlled HIV infection

Even after CD4 count recovery on antiretroviral therapy, HIV infection is associated with decreased response to most vaccines compared to the general population. Chronic infections with viruses such as cytomegalovirus (CMV), hepatitis B virus (HBV), and hepatitis C virus (HCV), which are more prevalent in HIV-infected populations, have been linked to immune dysfunction and decreased vaccine response in the general population. However, whether co-infection with these other viruses contributes to the decreased vaccine response seen in adults with well-controlled HIV infection is unknown. We conducted a secondary analysis of data and serum from adults with well-controlled HIV infection from an inactivated polio vaccine trial (224 subjects) and a pneumococcal conjugate vaccine study (128 subjects). We evaluated the association of CMV, HBV, or HCV co-infection with post-vaccination antibody levels using both univariate and multivariate analyses, controlling for factors such as age, race, CD4 count, comorbidities, smoking status, and baseline antibody levels. Ninety-three percent, 7%, and 14% of subjects were co-infected with CMV, HBV, and HCV respectively. On both univariate and multivariate analysis, neither CMV nor HCV co-infection were significantly associated with post-vaccination antibody levels to either vaccine. HBV co-infection was significantly associated with post-vaccination antibody concentrations for pneumococcal serotype 7F on univariate analysis and 6A on multivariate analysis, but the association was with higher antibody concentrations. In conclusion, co-infection with CMV, HBV, or HCV does not appear to contribute to the decreased vaccine response seen in adults with well-controlled HIV infection.

Long-term seroprotective response of trivalent seasonal influenza vaccine in HIV-infected children, regardless of immunogenicity before immunisation

Influenza vaccination can reduce disease in HIV-infected children. The durability of the antibody response after trivalent influenza vaccine is important for management. The aim of this prospective study was to assess the durability of seroprotection for trivalent influenza vaccine strains and the factors effecting seroprotective response regardless of immunogenicity before trivalent influenza vaccine at one and six months after immunisation. Hemagglutination inhibition assay was done at one and six months. Seventy-five HIV-infected children were enrolled after vaccination. Four children were lost to follow-up. None of the children had confirmed influenza infection between immunisation and hemagglutination inhibition at six months after influenza vaccination. Seventy-one children were included in the final analysis and immunogenicity of trivalent influenza vaccine strains at one and six months. Of these, 27 (38%) had complete seroprotection (Group A) and 44 (62%) had non-complete seroprotection (Group B). Sex, age and the body mass index of both groups were not different from each other (p > 0.05). There was a higher mean CD4 level and more children with RNA ≤40 copies/mL among Group A compared with Group B (p < 0.05). Other factors did not differ significantly. The durability of the seroprotective response after trivalent influenza vaccine was associated with a high CD4 level and virological suppression before vaccination.

Low expression of activation marker CD69 and chemokine receptors CCR5 and CXCR3 on memory T cells after 2009 H1N1 influenza A antigen stimulation in vitro following H1N1 vaccination of HIV-infected individuals

Unlike well-studied antibody responses to pandemic 2009 H1N1 influenza A virus vaccines in human immunodeficiency virus-infected (HIV+) individuals, less well understood are cell-mediated immune (CMI) responses to this antigen in this susceptible population. We investigated such influenza-specific CMI responses in 61 HIV+ individuals and in 20 HIV-negative (HIV-) healthy controls. Each was vaccinated with a single licensed dose of inactivated, split-virion vaccine comprised of the influenza A/California/7/2009 (H1N1) virus-like strain. Cells collected just prior to vaccination and at 1 and 3 months afterwards were stimulated in vitro with dialyzed vaccine antigen and assayed by flow cytometry for cytokines TNF-α, IFN-γ, IL-2, and IL-10, for degranulation marker CD107a, as well as phenotypes of memory T-cell subpopulations. Comparable increases of cytokine-producing and CD107a-expressing T cells were observed in both HIV+ subjects and healthy HIV-controls. However, by 3 months post-vaccination, in vitro antigen stimulation of peripheral blood mononuclear cells induced greater expansion in controls of both CD4 and CD8 central memory and effector memory T cells, as well as higher expression of the activation marker CD69 and chemokine receptors CCR5 and CXCR3 than in HIV+ subjects. We concluded CD4+ and CD8+ memory T cells produce cytokines at comparable levels in both groups, whereas the expression after in vitro stimulation of molecules critical for cell migration to infection sites are lower in the HIV+ than in comparable controls. Further immunization strategies against influenza are needed to improve the CMI responses in people living with HIV.

Kinetics of Hemagglutination-Inhibiting Antibodies Following Maternal Influenza Vaccination Among Mothers With and Those Without HIV Infection and Their Infants

BACKGROUND

We evaluated the immunogenicity of trivalent inactivated influenza vaccine (IIV3) in pregnant women with and those without human immunodeficiency virus (HIV) infection and the persistence of hemagglutination-inhibiting antibodies in mothers and infants.

METHODS

Antibodies were measured before vaccination, 1 month after vaccination, at delivery, and at postpartum week 24 in mothers and within 1 week of birth and at 8, 16, and 24 weeks of age in infants.

RESULTS

We enrolled 98 HIV-uninfected and 100 HIV-infected pregnant women, including 93% with a CD4(+) T-cell count of ≥ 200 cells/µL. Compared with HIV-uninfected women, HIV-infected women had lower seroconversion rates (ranging from 63%-92% vs 36%-40%), lower antibody titers through postpartum week 24, and overlapping antibody half-lives (ranging from 106-121 vs 87-153 days). Infant titers were lower than the maternal titers within 1 week of delivery, regardless of vaccine strain and HIV exposure status. Compared with HIV-unexposed infants, HIV-exposed infants had a similar transplacental influenza virus antibody transfer ratio, lower titers, and a lower frequency of titers ≥ 1:40 (ranging from 82%-95% vs 43%-79%) at birth and higher antibody half-lives (ranging from 43-45 vs 56-65 days).

CONCLUSIONS

Compared with HIV-uninfected pregnant women, HIV-infected pregnant women had lower antibody responses and persistence. Compared with HIV-unexposed infants, HIV-exposed infants had lower antibody levels at birth but similar antibody levels after 8 weeks of life. Early IIV3 administration during pregnancy did not decrease antibody titers among infants at birth.

Comparison of the Immunogenicity of Various Booster Doses of Inactivated Polio Vaccine Delivered Intradermally Versus Intramuscularly to HIV-Infected Adults

BACKGROUND

Inactivated polio vaccine (IPV) is necessary for global polio eradication because oral polio vaccine can rarely cause poliomyelitis as it mutates and may fail to provide adequate immunity in immunocompromised populations. However, IPV is unaffordable for many developing countries. Intradermal IPV shows promise as a means to decrease the effective dose and cost of IPV, but prior studies, all using 20% of the standard dose used in intramuscular IPV, resulted in inferior antibody titers.

METHODS

We randomly assigned 231 adults with well-controlled human immunodeficiency virus infection at a ratio of 2:2:2:1 to receive 40% of the standard dose of IPV intradermally, 20% of the standard dose intradermally, the full standard dose intramuscularly, or 40% of the standard dose intramuscularly. Intradermal vaccination was done using the NanoPass MicronJet600 microneedle device.

RESULTS

Baseline immunity was 87%, 90%, and 66% against poliovirus serotypes 1, 2, and 3, respectively. After vaccination, antibody titers increased a median of 64-fold. Vaccine response to 40% of the standard dose administered intradermally was comparable to that of the standard dose of IPV administered intramuscularly and resulted in higher (although not significantly) antibody titers. Intradermal administration had higher a incidence of local side effects (redness and itching) but a similar incidence of systemic side effects and was preferred by study participants over intramuscular administration.

CONCLUSIONS

A 60% reduction in the standard IPV dose without reduction in antibody titers is possible through intradermal administration.

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.

Durability of protective antibody titres is not enhanced by a two-dose schedule of an ASO3-adjuvanted pandemic H1N1 influenza vaccine in adult HIV-1-infected patients

The immune response after influenza vaccination is impaired in HIV-infected individuals and can be enhanced by a second dose. The durability of the antibody protection and its clinical benefit is not known. We investigated clinical symptoms and antibody titres against H1N1 influenza A following no dose, 1 dose, or 2 doses of an ASO3-adjuvanted H1N1 vaccine in HIV-infected patients. Seroprotection was found in 7.9%, 52.2%, and 57.3% of patients who received no dose, 1 dose, and 2 doses of the vaccine, respectively (p-value for group comparison < 0.001), after a median of 8.2 ± 1.6 months. Clinical symptoms suggestive of an influenza-like illness were slightly more frequently reported in the unvaccinated group. Vaccinated HIV-infected patients were more likely to be seroprotected at follow-up, but there was no difference comparing those who had received 1 or 2 doses of the vaccine.

High level antibody avidity is achieved in HIV-seropositive recipients of an inactivated split adjuvanted (AS03A) influenza vaccine

PURPOSE

More severe influenza disease and poor vaccine immunogenicity is reported in HIV-infected patients. We measured antibody avidity after influenza vaccination in HIV patients to assess vaccine efficacy.

METHODS

Two dosing strategies (Group1: single dose, n = 28. Group2: single dose plus booster, n = 36) with an AS03A-adjuvanted H1N12009 pandemic influenza vaccine (Arepanrix, GSK) were assessed in HIV patients. Serum hemagglutination inhibition (HAI) titers and antibody avidity reported as an avidity index (AI) were measured at days 21 and 42 and at 6 months.

RESULTS

Baseline HIV parameters were similar among all participants. Eighteen participants had measurable baseline HAI titers. In these subjects, AI was at ~9 at baseline and was not significantly increased by one or two vaccine doses. In those without detectable baseline antibodies, immunization induced modest antibody titers [Group1 HAI, 61 (26-144); Group2 HAI, 46 (28-76)] with high AI after one dose at day 21 [Group1 AI, 8.8 (7.3-10.7); Group2 AI, 8.9 (7.8-10.1)]. A second dose of vaccine generated significantly higher HAI titers at day 42 [Group1 HAI, 41 (18-90); Group2 HAI, 92 (64-132)] and persisted to 6 months [Group1 HAI, 9 (6-13); Group2 HAI, 19 (13-30)]. All subjects who produced detectable HAI titers after vaccination generated high antibody avidity (AI, 9-10), which persisted up to 6 months.

CONCLUSION

In participants initially seronegative, two doses of vaccine enabled a greater percentage of subjects to respond to the vaccine and elicited higher HAI titers. All subjects who produced detectable HAI titers also rapidly generated high AI in the short and long term. We demonstrate that high avidity antibodies can be achieved after vaccination and support a two-dose immunization strategy for HIV-positive subjects.

Influenza vaccination in immunocompromised patients: efficacy and safety

Yearly administration of the influenza vaccine is the main strategy to prevent influenza in immunocompromised patients. Here, we reviewed the recent literature regarding the clinical significance of the influenza virus infection, as well as the immunogenicity and safety of the influenza vaccine in HIV‑infected individuals, solid-organ and stem-cell transplant recipients and patients receiving biological agents. Epidemiological data produced during the 2009 influenza pandemic have confirmed that immunocompromised patients remain at high risk of influenza-associated complications, namely viral and bacterial pneumonia, hospitalization and even death. The immunogenicity of the influenza vaccine is overall reduced in immunocompromised patients, although a significant clinical protection from influenza is expected to be obtained with vaccination. Influenza vaccination is safe in immunocompromised patients. The efficacy of novel strategies to improve the immunogenicity to the vaccine, such as the use of adjuvanted vaccines, boosting doses and intradermal vaccination, needs to be validated in appropriately powered clinical trials.

Comparison of the immunogenicity of a monovalent influenza A/H1N1 2009 vaccine between healthy individuals, patients with chronic renal failure, and immunocompromised populations

BACKGROUND

Data on the immunogenicity (IG) of the influenza vaccine among patients at high risk of influenza-related complication are limited.

METHODS

We studied the antibody titer following a single dose of monovalent 2009 influenza A (H1N1) vaccine between groups of adult patients who were healthy, those with chronic renal failure (CRF), kidney transplant (KT) recipients, and human immunodeficiency virus (HIV)-infected patients. The IG (primary endpoints) was accessed at 4 weeks after vaccination. The secondary endpoint was safety of the vaccine.

RESULTS

A total of 293 patients were studied. Patients' mean age was 41(standard deviation [SD], 13.3) years old. At baseline, mean age (P < .001), history of vaccination in a prior year (P < .001), and geometric mean titers (GMT; P < .001) significantly differed between each groups and the majority (70%) of participants had the hemagglutination inhibition titer <1:10. The IG of the vaccine was highest in the healthy group (71.4 %). The response rate among CRF, KT, and HIV groups was 42.4% (risk ratios [RR], 0.72; 95% confidence interval [CI], 0.5-1.02), 31.9% (RR, 0.51; 95% CI, 0.34-0.76), and 29.7% (RR, 0.42; 95% CI, 0.3-0.6), respectively. The vaccine was well-tolerated in all studied groups. Thirty (10.2%) patients experienced at least 1 adverse reaction but systemic reaction was uncommon (3.4%).

CONCLUSIONS

A single dose of monovalent 2009 influenza A (H1N1) vaccine result in poor IG among high-risk populations, including CRF, KT and HIV patients.

2013 IDSA clinical practice guideline for vaccination of the immunocompromised host

An international panel of experts prepared an evidenced-based guideline for vaccination of immunocompromised adults and children. These guidelines are intended for use by primary care and subspecialty providers who care for immunocompromised patients. Evidence was often limited. Areas that warrant future investigation are highlighted.

Immunogenicity of Licensed Influenza A (H1N1) 2009 Monovalent Vaccines in HIV-Infected Children and Youth

BACKGROUND

With the emergence of pandemic influenza A (pH1N1) in 2009, children and youth infected with human immunodeficiency virus (HIV) were vulnerable because of immunologic impairment and the greater virulence of this infection in young persons.

METHODS

A multicenter study of the immunogenicity of 3 licensed influenza A (H1N1) monovalent vaccines (1 live attenuated and 2 inactivated) was conducted in children and youth with perinatal HIV infection, most of whom were receiving ≥3 antiretroviral drugs, had CD4% ≥15, and plasma HIV RNA levels <400 copies/mL. Serum hemagglutinin inhibition assay (HAI) antibody levels were measured and correlated with baseline demographic and clinical variables.

RESULTS

One hundred forty-nine subjects were enrolled at 26 sites in the United States and Puerto Rico. Over 40% had baseline HAI titers ≥40. For subjects aged 6 months to <10 years, 79% and 68%, respectively, achieved a ≥40- and ≥4-fold rise in HAI titers after the second dose of vaccine. Three weeks after a single immunization with an inactivated vaccine, similar immunogenicity results were achieved in youth aged 10-24 years. With multivariable analysis, only Hispanic ethnicity and CD4% ≥15 were associated with achieving both HAI titer ≥40- and ≥4-fold rise in titer.

CONCLUSIONS

Although licensed pH1N1 vaccines produced HAI titers that were considered to be protective in the majority of HIV-infected children and youth, the proportion with titers ≥40- and ≥4-fold rise in titer was lower than expected for children without HIV infection. Vaccine immunogenicity was lower in HIV-infected children and youth with evidence of immune suppression.

Immune activation and viral replication after vaccination with an influenza A H1N1 2009 vaccine in HIV-infected children receiving antiretroviral therapy

Immunization with a pandemic influenza A H1N1 2009 was recommended for HIV-infected patients. However, there is limited information concerning the impact of immunization with this vaccine on immune activation and HIV viral replication. In this study, 45 HIV-infected children and adolescents receiving antiretroviral therapy were immunized with a 2-dose series of nonadjuvated monovalent influenza A H1N1 2009 vaccine upon enrollment and approximately 1 month later. Immunogenicity was determined by haemagglutination inhibition assay. The level of immune activation was determined by identification of CD38 and HLA-DR on CD8+ T cells. Patients were divided into 2 groups which include patients who had an undetectable HIV viral load (HIV detectable group) and patients who show virological failure (HIV nondetectable group). The results showed seroconversion rate of 55.2% in HIV nondetectable group, whereas 31.3% was found in HIV detectable group. Both groups of patients showed no major increase in immune activation after immunization. Interestingly, a decrease in the frequency of CD8+ T cells that coexpressed CD38 and HLA-DR was observed after immunization in both groups of patients. We suggested that immunization with influenza A H1N1 2009 vaccine can induce immune response to the pandemic virus without major impact on HIV viral replication and immune activation.

Immune response after a single dose of the 2010/11 trivalent, seasonal influenza vaccine in HIV-1-infected patients and healthy controls

BACKGROUND

Immune response rates following influenza vaccination are often lower in HIV-infected individuals. Low vitamin D levels were correlated with weak immune response in cancer patients and are known to be lower in HIV-infected patients.

METHODS

Diagnostic study to determine immune response against the H1N1v component after a single, intramuscular dose of the 2010/11 seasonal, trivalent influenza vaccine (TIV) in adult HIV-infected and healthy controls scheduled for influenza vaccination (ClinicalTrials.gov Identifier: NCT01017172). Influenza A/H1N1 antibody titers (AB) were determined before and 21 days after vaccination by hemagglutination inhibition assay.

RESULTS

Immune response was not different between HIV-infected patients (n = 36) and healthy controls (n = 42) who were previously naïve to the H1N1v component of the TIV. Comparing HIV-infected patients (n = 55) and healthy controls (n = 63) who had received 1 or 2 doses of an AS03 adjuvanted H1N1 vaccine in the previous winter season (2009/10), seroconversion rate and the geometric mean AB titer after TIV of the HIV-infected patients were more than twice as high compared to healthy controls. This difference was mainly driven by the 2-dose schedule for HIV patients in 2009/10. Vitamin D levels were lower in HIV patients but did not correlate with immune response.

CONCLUSION

HIV-infected patients who had received 1 or 2 doses of an adjuvanted H1N1 vaccine in the previous year (2009/10) had a significant higher seroconversion rate following TIV as compared to healthy controls, indicating a stronger memory cell response due to the 2-dose schedule.

Representation of women and pregnant women in HIV research: a limited systematic review

BACKGROUND

HIV-related outcomes may be affected by biological sex and by pregnancy. Including women in general and pregnant women in particular in HIV-related research is important for generalizability of findings.

OBJECTIVE

To characterize representation of pregnant and non-pregnant women in HIV-related research conducted in general populations.

DATA SOURCES

All HIV-related articles published in fifteen journals from January to March of 2011. We selected the top five journals by 2010 impact factor, in internal medicine, infectious diseases, and HIV/AIDS.

STUDY ELIGIBILITY CRITERIA

HIV-related studies reporting original research on questions applicable to both men and women of reproductive age were considered; studies were excluded if they did not include individual-level patient data.

STUDY APPRAISAL AND SYNTHESIS METHODS

Articles were doubly reviewed and abstracted; discrepancies were resolved through consensus. We recorded proportion of female study participants, whether pregnant women were included or excluded, and other key factors.

RESULTS

In total, 2014 articles were published during this period. After screening, 259 articles were included as original HIV-related research reporting individual-level data; of these, 226 were determined to be articles relevant to both men and women of reproductive age. In these articles, women were adequately represented within geographic region. The vast majority of published articles, 183/226 (81%), did not mention pregnancy (or related issues); still fewer included pregnant women (n=33), reported numbers of pregnant women (n=19), or analyzed using pregnancy status (n=9).

LIMITATIONS

Data were missing for some key variables, including pregnancy. The time period over which published works were evaluated was relatively short.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

The under-reporting and inattention to pregnancy in the HIV literature may reduce policy-makers' ability to set evidence-based policy around HIV/AIDS care for pregnant women and women of child-bearing age.

HIV-infected patients show impaired cellular immune response to influenza vaccination compared to healthy subjects

Detailed data on cellular immune response to influenza vaccination in HIV-infected patients are lacking. We analyzed cellular (IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IFN-γ, TNF-α, GM-CSF) and humoral (IgG and IgM) immune response in 81 HIV-infected and 30 HIV-negative subjects, before (T0) and 4 weeks (T1) after receiving a single dose of trivalent MF59-adjuvanted influenza vaccine. No difference in humoral response (IgG or IgM) was demonstrated between the two groups. While an increase in most cytokines from T0 to T1 was observed in HIV-uninfected subjects, cytokines production did not significantly increased in HIV-infected patients. Exploring Th1 response, higher CD8 cells count was significantly associated with lower post-vaccination IFNγ levels, while a higher CD4 cells count was associated with a greater response. Exploring Th2 response, higher HIV viral load was significantly associated with reduced post-vaccination IL-10 levels. In conclusion, in HIV-infected patients influenza vaccination could have good efficacy in sustaining humoral response but cellular response appeared impaired.

Influenza vaccination in HIV-positive subjects: latest evidence and future perspective

Annual influenza vaccination is recommended for persons with human immunodeficiency virus (HIV) infection. Recent reports indicate that immunizations may increase IIeplication in infected individuals. Generally, vaccination against influenza is well tolerated in both children and adult individuals with HNIVand does not induce significant changes in viral load and CD4+ cell counts. The observed increase in viral replication is usually transient and a clear, measurable progression of the underlying HIV disease is hard to be determined. Several studies reported immunogenicity data in HIV+ population, by comparing diferfent influenza vaccines, adjuvanted or not, and different administration routes. Data are encouraging because an adequate immune response is shown, although split/subunit vaccines do not elicite an efficient immune response in these subjects. New strategies have been evaluated to increase the immune response in immunocompromised patients.The aim of this review is to evaluate tolerability, safety, immunogenicity and efficacy of vaccines actually approved for human use and to consider latest evidence and future perspective in HIV positive subjects.

Safety and immunogenicity of 2009 pH1N1 vaccination in HIV-infected pregnant women

BACKGROUND

Pregnant women infected with human immunodeficiency virus (HIV) may have particular vulnerability to 2009 pandemic H1N1 influenza (pH1N1) infection. The safety and immunogenicity of pH1N1 vaccination in HIV-infected pregnant women are unknown.

METHODS

HIV-infected women 18-39 years of age and 14-34 weeks' gestation on antiretroviral therapy received two 30-μg doses of unadjuvanted, inactivated pH1N1 vaccine 21 days apart. Hemagglutination inhibition titers were measured at entry, 21 days after dose 1, and 10 and 21 days after dose 2, and, in mothers and infants, at delivery and 3 and 6 months postdelivery.

RESULTS

No severe vaccine-related adverse events were observed among 127 subjects. At entry, 21% had seroprotective (≥1:40) titers. Seroprotection and seroresponse (≥4-fold rise) occurred in 73% and 66% after dose 1 and 80% and 72% after dose 2, respectively. Of women lacking seroprotection at entry, 66% attained seroprotection after dose 1 and 75% after dose 2. Seroprotective titers were present in 67% of mothers and 65% of infants at delivery (median 66 days after dose 2), 60% of mothers and 26% of infants at 3 months postdelivery, and 59% of mothers and 12% of infants at 6 months postdelivery.

CONCLUSIONS

Two 30-μg doses were moderately immunogenic in HIV-infected pregnant women. No concerning vaccine-related safety signals were observed. Seroprotection persisted in most women postpartum. Efficient transplacental antibody transfer occurred, but seroprotection in infants waned rapidly. Vaccination to protect HIV-infected pregnant women and their newborns from new influenza strains is feasible, but more immunogenic platforms should be evaluated. Clinical Trials Registration. NCT00992017.

High proportions of regulatory B and T cells are associated with decreased cellular responses to pH1N1 influenza vaccine in HIV-infected children and youth (IMPAACT P1088)

HIV-infected individuals have poor responses to inactivated influenza vaccines. To evaluate the potential role of regulatory T (Treg) and B cells (Breg), we analyzed their correlation with humoral and cell-mediated immune (CMI) responses to pandemic influenza (pH1N1) monovalent vaccine in HIV-infected children and youth. Seventy-four HIV-infected, 4- to 25-y old participants in a 2-dose pH1N1 vaccine study had circulating and pH1N1-stimulated Treg and Breg measured by flow cytometry at baseline, post-dose 1 and post-dose 2. Concomitantly, CMI was measured by ELISPOT and flow cytometry; and antibodies by hemagglutination inhibition (HAI). At baseline, most of the participants had pH1N1-specific IFNγ ELISPOT responses, whose magnitude positively correlated with the baseline pH1N1, but not with seasonal H1N1 HAI titers. pH1N1-specific IFNγ ELISPOT responses did not change post-dose 1 and significantly decreased post-dose 2. In contrast, circulating CD4+CD25+% and CD4+FOXP3+% Treg increased after vaccination. The decrease in IFNγ ELISPOT results was marginally associated with higher pH1N1-specific CD19+FOXP3+ and CD4+TGFβ+% Breg and Treg, respectively. In contrast, increases in HAI titers post-dose 1 were associated with significantly higher circulating CD19+CD25+% post-dose 1, whereas increases in IFNγ ELISPOT results post-dose 1 were associated with higher circulating CD4+/C8+CD25+FOXP3+%. In conclusion, in HIV-infected children and youth, influenza-specific Treg and Breg may contribute to poor responses to vaccination. However, robust humoral and CMI responses to vaccination may result in increased circulating Treg and/or Breg, establishing a feed-back mechanism.

Comparative analysis of hemagglutination inhibition titers generated using temporally matched serum and plasma samples

Influenza-specific hemaggluitination inhibition (HAI) antibody titer, an indicator of immunity to influenza, is often used to measure exposure to influenza in surveillance and immunogenicity studies. Traditionally, serum has been the specimen of choice for HAI assays, but a desire to reduce the amount of blood collected during studies and the availability of plasma in archived sample collections warrant the evaluation of plasma for HAI titer. Therefore, the relationship between serum and plasma HAI titer values is of great interest. Here, we compare HAI titers determined on temporally matched serum and plasma (citrated and heparinized) using influenza A and B viruses. Bland-Altman plots, McNemar's test, and geometric coefficient of variation were used respectively for evaluating agreement, correlation and variability in the serum-plasma titer results. We observed a high degree of agreement (80.5%–98.8%) and correlation (r = 0.796–0.964) in the serum and matched plasma titer values although plasma titers were generally lower than corresponding serum titers. Calculated seropositive (HAI ≥40) rates were higher using serum titers than with plasma titers, but seroconversion rates were unaffected by sample type. Stronger agreement and decreased variability in titers were seen between serum and citrated plasma than between serum and heparinized plasma. Overall, these data suggest that serum or plasma can be used in serodiagnostic HAI assays, but seropositive rates may be underestimated using plasma HAI titers. The type of anticoagulant present in plasma may affect HAI titer values and warrants further investigation.

Cellular and humoral immune responses to pandemic influenza vaccine in healthy and in highly active antiretroviral therapy-treated HIV patients

Influenza vaccination is recommended for HAART-treated HIV patients to prevent influenza illness and complications. Due to the known ability of T cells to mediate a broadly cross-reactive response, vaccination effectiveness in cell-mediated immune (CMI) response induction is a main objective in new influenza vaccination strategies. Nevertheless, data on CMI responses after pandemic vaccination in HIV subjects are still missing. In the present study, the ability of a single dose of adjuvanted pandemic influenza vaccine to induce humoral and CMI responses was compared in HAART-treated HIV patients and in healthcare workers. Healthcare workers (HCW, n=65) and HAART-treated HIV patients (HIV, n=67) receiving pandemic vaccination were enrolled and analyzed before (t0) and after (t1) vaccination. The analysis of strain-specific humoral response was performed by HAI assay; CMI against pandemic (A/H1N1/Cal/09) and seasonal (A/H1N1/Brisb/07 and A/H3N2/Brisb/07) strains was analyzed by ELISpot and intracellular staining followed by flow cytometry. Pandemic vaccination was effective in inducing both humoral and cell-mediated responses in HAART-treated HIV patients as well as in HCWs. A large fraction of both HCWs and HIV-infected patients showed a T cell response to the pandemic strain before vaccination, suggesting possible previous exposure to A/H1N1/pdm/09 and/or cross-reactive T cells. Notably, pandemic vaccine was also able to boost cross-reactive immune responses to seasonal strains. Finally, a weaker boost of both strain-specific and cross-reactive T cell immunity was found in individuals showing a higher baseline response. These data show the effectiveness of adjuvanted pandemic vaccine to induce both humoral and cellular (strain-specific and cross-reactive) immune responses in HIV patients similar to HCWs.

Immune response after one or two doses of pandemic influenza A (H1N1) monovalent, AS03-adjuvanted vaccine in HIV infected adults

INTRODUCTION

Continued research is needed to evaluate and improve the immunogenicity of influenza vaccines in HIV infected patients. We aimed to determine the antibody responses after one or two doses of the AS03-adjuvanted pandemic influenza A (H1N1) vaccine in HIV infected patients.

METHOD

Following the influenza season 2009/2010, 219 HIV infected patients were included and divided into three groups depending on whether they received none (n=60), one (n=31) or two (n=128) doses of pandemic influenza A (H1N1) vaccine. At inclusion, antibody titers for all patients were analyzed and compared to pre-pandemic antibody titers analyzed from serum samples in a local storage facility.

RESULTS

4-9 months after a single immunization, we found a seroprotection rate of 77.4% and seroconversion rate of 67.7%. After two immunizations the rates increased significantly to seroprotection rate of 97.7% and seroconversion rate of 86.7%.

CONCLUSION

A single dose of AS03-adjuvanted pandemic influenza A (H1N1) vaccine created an adequate immune response in HIV infected patients lasting as long as 4-9 months. Two doses improved the immunogenicity further.