Influenzavirus infection is a primary cause of febrile respiratory illness in HIV-infected adults, despite vaccination

Correlates of Breakthrough SARS-CoV-2 Infections in People with HIV: Results from the CIHR CTN 328 Study

COVID-19 breakthrough infection (BTI) can occur despite vaccination. Using a multi-centre, prospective, observational Canadian cohort of people with HIV (PWH) receiving ≥2 COVID-19 vaccines, we compared the SARS-CoV-2 spike (S) and receptor-binding domain (RBD)-specific IgG levels 3 and 6 months post second dose, as well as 1 month post third dose, in PWH with and without BTI. BTI was defined as positivity based on self-report measures (data up to last study visit) or IgG data (up to 1 month post dose 3). The self-report measures were based on their symptoms and either a positive PCR or rapid antigen test. The analysis was restricted to persons without previous COVID-19 infection. Persons without BTI remained COVID-19-naïve until ≥3 months following the third dose. Of 289 participants, 92 developed BTI (31.5 infections per 100 person-years). The median days between last vaccination and BTI was 128 (IQR 67, 176), with the most cases occurring between the third and fourth dose (n = 59), corresponding to the Omicron wave. In analyses adjusted for age, sex, race, multimorbidity, hypertension, chronic kidney disease, diabetes and obesity, a lower IgG S/RBD (log10 BAU/mL) at 1 month post dose 3 was significantly associated with BTI, suggesting that a lower IgG level at this time point may predict BTI in this cohort of PWH.

Acute Respiratory Infection Incidence and Outpatient Antibiotic Prescription Patterns in People With or Without Human Immunodeficiency Virus Infection: A Virtual Cohort Study

Background

Inappropriate antibiotic use in acute respiratory infections (ARIs) is a major public health concern; however, data for people with human immunodeficiency virus (PWH) are limited.

Methods

The HIV Virtual Cohort Study is a retrospective cohort of adult Department of Defense beneficiaries. Male PWH cases (n = 2413) were matched 1:2 to controls without HIV (n = 4826) by age, gender, race/ethnicity, and beneficiary status. Acute respiratory infection encounters between 2016 and 2020 and corresponding antibiotic prescriptions were characterized as always, sometimes, or never appropriate based on International Classification of Diseases, Tenth Revision coding. Incidence of ARI encounters and antibiotic appropriateness were compared between PWH and controls. Subgroup analyses were assessed by CD4 count and viral load suppression on antiretroviral therapy.

Results

Mean rates of ARI encounters were similar for PWH (1066 per 1000 person-years) and controls (1010 per 1000 person-years); however, the rate was double among PWH without viral load (VL) suppression (2018 per 1000 person-years). Antibiotics were prescribed in 26% of encounters among PWH compared to 34% for controls (P ≤ .01); antibiotic use was "never" appropriate in 38% of encounters with PWH and 36% in controls. Compared to controls, PWH received more sulfonamides (5.5% vs 2.7%; P = .001), and variation existed among HIV subgroups in the prescription of sulfonamides, fluoroquinolones, and β-lactams.

Discussion

Acute respiratory infection encounters were similar for PWH and those without HIV; however, PWH with lower CD4 counts and/or nonsuppressed VL had more frequent ARI visits. Inappropriate antibiotic use for ARIs was high in both populations, and focused interventions to improve antibiotic appropriateness for prescribers caring for PWH should be pursued.

Antibiotic Prescribing for Acute Respiratory Illnesses in Persons with HIV compared to Persons without HIV

Background

Antibiotic overuse increases healthcare cost and promotes antimicrobial resistance. People with HIV (PWH) who develop acute respiratory infections (ARI) may be assumed “higher risk,” compared with non-PWH, but comparative antibiotic use evaluations have not been performed.

Methods

This observational, single-center study compared antibiotic prescribing in independent clinical encounters for PWH and non-PWH diagnosed with ARI in outpatient clinical practices using ICD 10 codes between January 1, 2014 and April 30, 2018. Fisher’s exact test compared categorical variables with antibiotic prescribing patterns.

Results

There were 209 patients in the PWH cohort vs. 398 patients in the non-PWH cohort. PWH had median CD4+ count of 610 cells/mm3 with 91% on antiretroviral therapy and 78% were virally suppressed. Thirty-seven percent of all visits resulted in an antibiotic prescription, 89% were inappropriate. Antibiotics were prescribed more frequently in non-PWH (35% PWH vs. 40% non-PWH; p 0.172) and managed according to guidelines more often in PWH (37% PWH vs. 30% non-PWH; p 0.039). Antibiotics were prescribed appropriately most frequently in PWH managed by HIV clinicians (29% PWH managed by HIV clinician vs. 12% PWH managed by non-HIV clinician vs. 8% non-PWH p 0.010). HIV clinicians prescribed antibiotics for a mean duration of 5.9 days vs. PWH managed by a non-HIV clinician for 9.1 days vs. non-PWH for 7.6 days (p <0.0001).

Conclusion

Outpatient antibiotic overuse remains prevalent among patients evaluated for ARI. We found less frequent inappropriate antibiotic use in PWH. Prescriber specialty, rather than HIV diagnosis, was related to appropriateness of antimicrobial prescribing.

Factors Associated with Severe COVID-19 and Post-Acute COVID-19 Syndrome in a Cohort of People Living with HIV on Antiretroviral Treatment and with Undetectable HIV RNA

SARS-CoV-2 can produce both severe clinical conditions and long-term sequelae, but data describing post-acute COVID-19 syndrome (PACS) are lacking for people living with HIV (PLWH). We aimed at assessing the prevalence and factors associated with severe COVID-19 and PACS in our cohort. We included all unvaccinated adult PLWH on antiretroviral treatment and plasma HIV-RNA < 40 cp/mL since at least six months before SARS-CoV-2 infection at the Infectious and Tropical Diseases Unit of Padua (Italy), from 20 February 2020 to 31 March 2021. COVID-19 severity was defined by WHO criteria; PACS was defined as the persistence of symptoms or development of sequelae beyond four weeks from SARS-CoV-2 infection. Demographic and clinical variables were collected, and data were analyzed by non-parametric tests. 123 subjects meeting the inclusion criteria among 1800 (6.8%) PLWH in care at the Infectious and Tropical diseases Unit in Padua were diagnosed with SARS-CoV-2 infection/COVID-19 during the study period. The median age was 51 years (40−58), 79.7% were males, and 77.2% of Caucasian ethnicity. The median CD4+ T-cell count and length of HIV infection were 560 cells/mmc (444−780) and 11 years, respectively. Of the patients, 35.0% had asymptomatic SARS-CoV-2 infection, 48% developed mild COVID-19, 17.1% presented moderate or severe COVID-19 requiring hospitalization and 4.1% died. Polypharmacy was the single independent factor associated with severe COVID-19. As for PACS, among 75 patients who survived SARS-CoV-2 symptomatic infection, 20 (26.7%) reported PACS at a median follow-up of six months: asthenia (80.0%), shortness of breath (50.0%) and recurrent headache (25.0%) were the three most common complaints. Only the severity of the COVID-19 episode predicted PACS after adjusting for relevant demographic and clinical variables. In our study, PLWH with sustained viral suppression and good immunological response showed that the risk of hospital admission for COVID-19 was low, even though the severity of the disease was associated with high mortality. In addition, the likelihood of developing severe COVID-19 and PACS was mainly driven by similar risk factors to those faced by the general population, such as polypharmacy and the severity of SARS-CoV-2 infection.

Pulmonary Immune Dysregulation and Viral Persistence During HIV Infection

Despite the success of antiretroviral therapy (ART), people living with HIV continue to suffer from high burdens of respiratory infections, lung cancers and chronic lung disease at a higher rate than the general population. The lung mucosa, a previously neglected HIV reservoir site, is of particular importance in this phenomenon. Because ART does not eliminate the virus, residual levels of HIV that remain in deep tissues lead to chronic immune activation and pulmonary inflammatory pathologies. In turn, continuous pulmonary and systemic inflammation cause immune cell exhaustion and pulmonary immune dysregulation, creating a pro-inflammatory environment ideal for HIV reservoir persistence. Moreover, smoking, gut and lung dysbiosis and co-infections further fuel the vicious cycle of residual viral replication which, in turn, contributes to inflammation and immune cell proliferation, further maintaining the HIV reservoir. Herein, we discuss the recent evidence supporting the notion that the lungs serve as an HIV viral reservoir. We will explore how smoking, changes in the microbiome, and common co-infections seen in PLWH contribute to HIV persistence, pulmonary immune dysregulation, and high rates of infectious and non-infectious lung disease among these individuals.

CTN 328: immunogenicity outcomes in people living with HIV in Canada following vaccination for COVID-19 (HIV-COV): protocol for an observational cohort study

INTRODUCTION

Most existing vaccines require higher or additional doses or adjuvants to provide similar protection for people living with HIV (PLWH) compared with HIV-uninfected individuals. Additional research is necessary to inform COVID-19 vaccine use in PLWH.

METHODS AND ANALYSIS

This multicentred observational Canadian cohort study will enrol 400 PLWH aged >16 years from Montreal, Ottawa, Toronto and Vancouver. Subpopulations of PLWH of interest will include individuals: (1) >55 years of age; (2) with CD4 counts <350 cells/mm3; (3) with multimorbidity (>2 comorbidities) and (4) 'stable' or 'reference' PLWH (CD4 T cells >350 cells/mm3, suppressed viral load for >6 months and <1 comorbidity). Data for 1000 HIV-negative controls will be obtained via a parallel cohort study (Stop the Spread Ottawa), using similar time points and methods. Participants receiving >1 COVID-19 vaccine will attend five visits: prevaccination; 1 month following the first vaccine dose; and at 3, 6 and 12 months following the second vaccine dose. The primary end point will be the percentage of PLWH with COVID-19-specific antibodies at 6 months following the second vaccine dose. Humoral and cell-mediated immune responses, and the interplay between T cell phenotypes and inflammatory markers, will be described. Regression techniques will be used to compare COVID-19-specific immune responses to determine whether there are differences between the 'unstable' PLWH group (CD4 <350 cells/mm3), the stable PLWH cohort and the HIV-negative controls, adjusting for factors believed to be associated with immune response. Unadjusted analyses will reveal whether there are differences in driving factors associated with group membership.

ETHICS AND DISSEMINATION

Research ethics boards at all participating institutions have granted ethics approval for this study. Written informed consent will be obtained from all study participants prior to enrolment. The findings will inform the design of future COVID-19 clinical trials, dosing strategies aimed to improve immune responses and guideline development for PLWH.

TRIAL REGISTRATION NUMBER

NCT04894448.

HIV Infection and Persistence in Pulmonary Mucosal Double Negative T Cells In Vivo

The lungs are relatively unexplored anatomical human immunodeficiency virus (HIV) reservoirs in the antiretroviral therapy (ART) era. Double negative (DN) T cells are a subset of T cells that lack expression of CD4 and CD8 (CD4^- CD8^-) and may have both regulatory and effector functions during HIV infection. Notably, circulating DN T cells were previously described as cellular HIV reservoirs. Here, we undertook a thorough analysis of pulmonary versus blood DN T cells of people living with HIV (PLWH) under ART. Bronchoalveolar lavage (BAL) fluid and matched peripheral blood were collected from 35 PLWH on ART and 16 uninfected volunteers without respiratory symptoms. Both PLWH and HIV-negative (HIV^-) adults displayed higher frequencies of DN T cells in BAL versus blood, and these cells mostly exhibited an effector memory phenotype. In PLWH, pulmonary mucosal DN T cells expressed higher levels of HLA-DR and several cellular markers associated with HIV persistence (CCR6, CXCR3, and PD-1) than blood. We also observed that DN T cells were less senescent (CD28^- CD57⁺) and expressed less immunosuppressive ectonucleotidase (CD73/CD39), granzyme B, and perforin in the BAL fluid than in the blood of PLWH. Importantly, fluorescence-activated cell sorter (FACS)-sorted DN T cells from the BAL fluid of PLWH under suppressive ART harbored HIV DNA. Using the humanized bone marrow-liver-thymus (hu-BLT) mouse model of HIV infection, we observed higher infection frequencies of lung DN T cells than those of the blood and spleen in both early and late HIV infection. Overall, our findings show that HIV is seeded in pulmonary mucosal DN T cells early following infection and persists in these potential cellular HIV reservoirs even during long-term ART.IMPORTANCE Reservoirs of HIV during ART are the primary reasons why HIV/AIDS remains an incurable disease. Indeed, HIV remains latent and unreachable by antiretrovirals in cellular and anatomical sanctuaries, preventing its eradication. The lungs have received very little attention compared to other anatomical reservoirs despite being immunological effector sites exhibiting characteristics ideal for HIV persistence. Furthermore, PLWH suffer from a high burden of pulmonary non-opportunistic infections, suggesting impaired pulmonary immunity despite ART. Meanwhile, various immune cell populations have been proposed to be cellular reservoirs in blood, including CD4^- CD8^- DN T cells, a subset that may originate from CD4 downregulation by HIV proteins. The present study aims to describe DN T cells in human and humanized mice lungs in relation to intrapulmonary HIV burden. The characterization of DN T cells as cellular HIV reservoirs and the lungs as an anatomical HIV reservoir will contribute to the development of targeted HIV eradication strategies.

Adjuvanted-influenza vaccination in patients infected with HIV: a systematic review and meta-analysis of immunogenicity and safety

Adjuvanted-influenza vaccination is an efficient method for enhancing the immunogenicity of influenza split-virus vaccines for preventing influenza. However, the medical community's understanding of its performance in patients infected with HIV remains limited. To identify the advantages, we conducted a systematic review and meta-analysis with randomized controlled trials (RCTs) and cohort and case-control studies that have the immunogenicity and safety of influenza vaccines in patients infected with HIV as outcomes. We searched six different databases, and 1698 patients infected with HIV in 11 studies were included. Statistical analysis was performed to calculate the pooled standardized mean differences (SMD) or relative risk (RR) and 95% confidence interval (CI). Regarding immunogenicity, the pooled SMD of GMT (Geometric mean titer) for A/H1N1 was 0.61 (95%CI (0.40,0.82)), the pooled RR of seroconversion was 1.34 (95%CI (0.91,1.98)) for the H1N1 vaccine, 1.27(95%CI (0.64,2.52)) for the H3N2 vaccine, 1.19(95%CI (0.97,1.46)) for the B-type influenza vaccine. The pooled RR of seroprotection was 1.61 (95%CI (1.00,2.58)) for the H1N1 vaccine, 1.06 (95%CI(0.83,1.35)) for the H3N2 vaccine, and 1.13(95%CI(0.91,1.41)) for the B-type vaccine. Adjuvanted-influenza vaccination showed good general tolerability in patients infected with HIV, with the only significant increase being the rate of local pain at the injection site (RR = 2.03, 95%CI (1.06,3.86)). In conclusion, all studies evaluating injected adjuvanted influenza vaccination among patients infected with HIV showed acceptable levels of safety and immunogenicity.

Interactions Between NS1 of Influenza A Viruses and Interferon-α/β: Determinants for Vaccine Development

Influenza A viruses (IAVs) cause mild to severe infections in humans with considerable socioeconomic and global health consequences. The host interferon (IFN)-α/β response, critical as the first line of defense against foreign pathogens, is induced upon detection of IAV genomic RNA in infected cells by host innate pattern recognition receptors. IFN-α/β production and subsequent activation of cell signaling result in the expression of antiviral IFN-stimulated genes whose products target various stages of the IAV life cycle to inhibit viral replication and the spread of infection and establish an antiviral state. IAVs, however, encode a multifunctional virulence factor, nonstructural protein 1 (NS1), that directly antagonizes the host IFN-α/β response to support viral replication. In this review, we highlight the mechanisms by which NS1 suppresses IFN-α/β production and subsequent cell signaling, and consider, therefore, the potential for recombinant IAVs lacking NS1 to be used as live-attenuated vaccines.

Serological response to trivalent inactivated influenza vaccine in HIV-infected adults in Singapore

A cohort of 81 HIV-infected participants received seasonal trivalent inactivated influenza vaccine (TIV) and their humoral responses were monitored using hemagglutination inhibition (HAI) assay and enzyme-linked immunosorbent assay (ELISA). Three weeks after the vaccination, the percentage of the cohort that had an HAI titer of >1:40 was 35% (for H1N1), 43% (for H3N2) and 19% (for influenza B). An increase in HAI titer can be achieved by an increase in magnitude of the antibody responses, which can be measured by an increase in ELISA titer; as well as a quality improvement of the antibody responses through increased avidity to the virus. For some individuals, an increase in avidity alone is sufficient to reach the sero-protective titer. Notably, a number of volunteers showed an increase in ELISA titer without a rise in HAI titer. A total of 24 participants (30%) did not show any significant increase in both HAI and ELISA tests after vaccination. Apart from a lower peripheral CD4⁺ T cell count, the non responders' peripheral blood mononuclear cells (PBMC) also had a higher IL-10 mRNA expression after TIV vaccination ex vivo. Cytokine profiling demonstrated that, apart from a weaker MCP-1 expression in the non-responder group, PBMC from both groups responded comparably to lipopolysaccharide (LPS) stimulation in vitro. Since only 3 participants developed sero-protective titers against all 3 subtypes after vaccination, our study highlights a need to enhance the immunogenicity of the subunit vaccine for this population, potentially through harnessing the innate immunity with an external adjuvant.

Predictors for and coverage of influenza vaccination among HIV-positive patients: a cross-sectional survey

OBJECTIVES

Influenza vaccination is recommended for HIV-infected patients, but limited data about vaccination rates are available. The aim of this study was to evaluate the coverage of and predictors for influenza vaccination among HIV-positive patients.

METHODS

All HIV-positive patients who visited the HIV out-patient department of the University Hospital of Vienna, Austria, between June and August 2015 were asked to participate in this survey by completing a questionnaire.

RESULTS

A total of 455 HIV-positive patients completed a questionnaire, with 359 male and 96 female participants with a mean age of 46 years. The influenza vaccination rate for the previous season (2014/2015) was 11.9% [n = 54/455; 95% confidence interval (CI) 9.2-15.2%]. Older age was significantly associated with a positive influenza vaccination status. Obtaining information through a medical consultation or receiving a direct recommendation for vaccination by a physician had a significant impact on vaccination behaviour. The probability of being vaccinated against influenza was about 13 times higher among patients who received a recommendation for vaccination by their family physician or by their HIV specialist (P < 0.001). Important reasons for declining vaccination were fear of side effects (39%), not considering influenza as a severe disease (36%) and reasons related to HIV: 17% were worried that the vaccine could worsen the course of HIV infection and 16% believed vaccination would fail because of their compromised immune system.

CONCLUSIONS

A low influenza vaccination rate of 11.9% was detected in this HIV-positive cohort. The most effective impact for a positive vaccination status was direct recommendation of the influenza vaccine by the attending physician.

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.

Duration of Influenza Virus Shedding Among HIV-Infected Adults in the cART Era, 2010-2011

The duration of influenza virus shedding in HIV-infected adults is unknown and could affect quarantine and treatment recommendations. Participants were monitored for influenza-like illness (ILI), defined as fever and cough or sore throat, using weekly telephone audio computer-assisted self-interviews. Those with ILI were further evaluated at three HIV specialty clinics. For those with influenza, we collected nasopharyngeal washes every 3 days after the date of confirmed influenza infection for 21-28 days; specimens underwent reverse transcriptase - polymerase chain reaction (RT-PCR) and viral culture. Duration of influenza virus shedding was the interval from the date of onset (day 0) of ILI to the date of last culture-positive specimen. Characteristics were compared between patients with and without influenza using Fisher's exact test. We used the Wilcoxon rank-sum test to examine factors that may have affected influenza virus shedding. From October 2010 to April 2011, we enrolled 961 participants in syndromic surveillance and diagnosed 20 patients with influenza whose characteristics were as follows: median age 48 years (interquartile range [IQR]: 43-53), 60% male, 50% non-Hispanic black, 95% had been prescribed combination highly active antiretroviral therapy (cART), 85% were virologically suppressed (HIV RNA <400 copies/ml), median CD4 cell count 317 cells/mm³ (IQR: 190-544), and median follow-up time 21 days (IQR: 19-22). Compared with persons without influenza, persons with influenza were more likely to be older, use injection drugs, and have a lower median CD4 cell count and were less likely to have had an influenza vaccination in the past 12 months. Median durations of shedding, PCR detection, and ILI symptoms were 3 (IQR: 0-5), 10 (IQR: 6-15), and 14 days (IQR: 12-26), respectively. Median days of shedding were similar among patients with and without any prior influenza vaccination (0 vs. 4, p = .448), HIV viral suppression (2 vs. 6, p = .053), and oseltamivir use (5 vs. 0, p = .083). HIV-infected persons on cART in our study shed influenza virus for a similar duration as that reported for HIV-uninfected persons.

Immunization of HIV-infected adult patients - French recommendations

Human immunodeficiency virus (HIV)-infected patients remain at increased risk of infection including vaccine-preventable diseases. Vaccines are therefore critical components in the protection of HIV-infected patients from an increasing number of preventable diseases. However, missed opportunities for vaccination among HIV-infected patients persist and vaccine coverage in this population could be improved. This article presents the French recommendations regarding immunization of HIV-infected adults in the light of the evidence-based literature on the benefits and the potential risks of vaccines among this vulnerable population.

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 hemagglutination inhibition and microbead array assays for the measurement of influenza antibody levels in HIV-infected adults

INTRODUCTION

Determining vaccine responsiveness is challenging in immune compromised individuals. The microbead array (MBA) assay is a rapid, inexpensive test for evaluating influenza vaccine immunogenicity. MBA performance was compared to hemagglutination inhibition assay (HAI) utilizing HIV seropositive vaccine recipient specimens.

METHODS

CTN 253 evaluated standard dose, single antigen, inactivated split adjuvanted (AS03(A)) H1N1 influenza vaccine (Arepanrix) vs standard dose plus booster. CTN237 evaluated three doses of a seasonal, trivalent killed split non-adjuvanted influenza vaccine (Fluviral). Samples of convenience from 75 CTN 253 and 58 CTN 237 participants were evaluated by MBA and HAI. MBA seroreactivity cut-offs of 500 and 1000 mean fluorescent intensity were used to compare those derived by HAI [titer ≥40 (seroprotection) and 4-fold titer increase from baseline (seroconversion)].

RESULTS

CTN253: Using a MBA cut-off of 500, 75% and 59% had seroreactive titers at visit 2 and 78% and 61% at visit 3 for the single versus double dose study arms. Many participants were categorized differently by the HAI and MBA tests, with raw agreement of 59% at visit 2 and 57% at visit 3. CTN 237: Baseline MBA medians (IQR) were 803 (12-2626) for the A/Brisbane strain and 460 (14-1758) for the B/Florida strain. Using a cut-off of 500 yielded for the A/Brisbane strain seroreactivity rates of 44%, 58%, and 63% were observed for the three doses of vaccine tested. The raw agreement was 47%. B/Florida strain analyses yielded similar results. For all strains assessed in both studies, no relationship between MBA values and baseline variables was identified.

CONCLUSION

The concordance of results between the MBA assay and the HAI assay is very low. MBA assay may be more sensitive than the HAI assay suggesting that it was either detecting more false-positive results and/or that the HAI assay had more false negative.

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.

Influenza virus prevalence in asymptomatic and symptomatic subjects during pandemic and postpandemic periods

BACKGROUND

In 2009, Influenza A(H1N1)pdm09 had a major effect on global health, causing thousands of deaths. However, the results of asymptomatic infection in transmission has not been well studied. We analyzed asymptomatic influenza infection in individuals with different risk factors for acquiring influenza in a university hospital.

METHODS

Respiratory samples from 100 children with respiratory symptoms, their asymptomatic caregivers, 100 asymptomatic HIV-infected patients, and 100 health care workers collected during 2009-2011 were tested for influenza by real time real-time polymerase chain reaction.

RESULTS

Influenza infection rate in symptomatic children was 44% and in asymptomatic adults it was 8.3% (P < .01). Children older than age 5 years had a 3.4 times greater chance of being infected during influenza season than younger children. Among the asymptomatic group, influenza was more frequent in caregivers (14%; P = .032) and a higher rate (31.8%) was observed if a child was infected during the 2009 pandemic. Contact with an infected child was an important risk factor for influenza acquisition (odds ratio, 3.8; 95% confidence interval, 1.1-13.2) among caregivers. The mean cluster of differentiation 4 T-cell count of HIV-positive patients infected with influenza was not statistically different from uninfected patients (P = .29).

CONCLUSIONS

Asymptomatic household contacts of symptomatic children may play an important role in community transmission and a more proactive intervention should be considered during future pandemics.

Determinants of vaccine immunogenicity in HIV-infected pregnant women: analysis of B and T cell responses to pandemic H1N1 monovalent vaccine

Influenza infections have high frequency and morbidity in HIV-infected pregnant women, underscoring the importance of vaccine-conferred protection. To identify the factors that determine vaccine immunogenicity in this group, we characterized the relationship of B- and T-cell responses to pandemic H1N1 (pH1N1) vaccine with HIV-associated immunologic and virologic characteristics. pH1N1 and seasonal-H1N1 (sH1N1) antibodies were measured in 119 HIV-infected pregnant women after two double-strength pH1N1 vaccine doses. pH1N1-IgG and IgA B-cell FluoroSpot, pH1N1- and sH1N1-interferon γ (IFNγ) and granzyme B (GrB) T-cell FluoroSpot, and flow cytometric characterization of B- and T-cell subsets were performed in 57 subjects. pH1N1-antibodies increased after vaccination, but less than previously described in healthy adults. pH1N1-IgG memory B cells (Bmem) increased, IFNγ-effector T-cells (Teff) decreased, and IgA Bmem and GrB Teff did not change. pH1N1-antibodies and Teff were significantly correlated with each other and with sH1N1-HAI and Teff, respectively, before and after vaccination. pH1N1-antibody responses to the vaccine significantly increased with high proportions of CD4+, low CD8+ and low CD8+HLADR+CD38+ activated (Tact) cells. pH1N1-IgG Bmem responses increased with high proportions of CD19+CD27+CD21- activated B cells (Bact), high CD8+CD39+ regulatory T cells (Treg), and low CD19+CD27-CD21- exhausted B cells (Bexhaust). IFNγ-Teff responses increased with low HIV plasma RNA, CD8+HLADR+CD38+ Tact, CD4+FoxP3+ Treg and CD19+IL10+ Breg. In conclusion, pre-existing antibody and Teff responses to sH1N1 were associated with increased responses to pH1N1 vaccination in HIV-infected pregnant women suggesting an important role for heterosubtypic immunologic memory. High CD4+% T cells were associated with increased, whereas high HIV replication, Tact and Bexhaust were associated with decreased vaccine immunogenicity. High Treg increased antibody responses but decreased Teff responses to the vaccine. The proportions of immature and transitional B cells did not affect the responses to vaccine. Increased Bact were associated with high Bmem responses to the vaccine.

Cellular and humoral cross-immunity against two H3N2v influenza strains in presumably unexposed healthy and HIV-infected subjects

Human cases of infection due to a novel swine-origin variant of influenza A virus subtype H3N2 (H3N2v) have recently been identified in the United States. Pre-existing humoral and cellular immunity has been recognized as one of the key factors in limiting the infection burden of an emerging influenza virus strain, contributing to restrict its circulation and to mitigate clinical presentation. Aim of this study was to assess humoral and cell-mediated cross immune responses to H3N2v in immuno-competent (healthy donors, n = 45) and immuno-compromised hosts (HIV-infected subjects, n = 46) never exposed to H3N2v influenza strain. Humoral response against i) H3N2v (A/H3N2/Ind/08/11), ii) animal vaccine H3N2 strain (A/H3N2/Min/11/10), and iii) pandemic H1N1 virus (A/H1N1/Cal/07/09) was analysed by hemagglutination inhibition assay; cell-mediated response against the same influenza strains was analysed by ELISpot assay. A large proportion of healthy and HIV subjects displayed cross-reacting humoral and cellular immune responses against two H3N2v strains, suggesting the presence of B- and T-cell clones able to recognize epitopes from emerging viral strains in both groups. Specifically, humoral response was lower in HIV subjects than in HD, and a specific age-related pattern of antibody response against different influenza strains was observed both in HD and in HIV. Cellular immune response was similar between HD and HIV groups and no relationship with age was reported. Finally, no correlation between humoral and cellular immune response was observed. Overall, a high prevalence of HD and HIV patients showing cross reactive immunity against two H3N2v strains was observed, with a slightly lower proportion in HIV persons. Other studies focused on HIV subjects at different stages of diseases are needed in order to define how cross immunity can be affected by advanced immunosuppression.

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.

HIV virological suppression influences response to the AS03-adjuvanted monovalent pandemic influenza A H1N1 vaccine in HIV-infected children

Design

Children with HIV are especially susceptible to complications from influenza infection, and effective vaccines are central to reducing disease burden in this population. We undertook a prospective, observational study to investigate the safety and immunogenicity of the inactivated split-virion AS03-adjuvanted pandemic H1N1(2009) vaccine in children with HIV.

Setting

National referral centre for Paediatric HIV in Ireland.

Sample

Twenty four children with HIV were recruited consecutively and received two doses of the vaccine. The serological response was measured before each vaccine dose (Day 0 and Day 28) and 2 months after the booster dose. Antibody titres were measured using a haemagglutination inhibition (HAI) assay. Seroprotection was defined as a HAI titre ≥ 1:40; seroconversion was defined as a ≥ fourfold increase in antibody titre and a postvaccination titre ≥ 1:40.

Main outcome measures

The seroconversion rates after prime and booster doses were 75% and 71%, respectively. HIV virological suppression at the time of immunization was associated with a significantly increased seroconversion rate (P = 0·009), magnitude of serological response (P = 0·02) and presence of seroprotective HAI titres (P = 0·017) two months after the booster dose. No other factor was significantly associated with the seroconversion/seroprotection rate. No serious adverse effects were reported. Vaccination had no impact on HIV disease progression. The AS03-adjuvanted pandemic H1N1 vaccine appears to be safe and immunogenic among HIV-infected children. A robust serological response appears to be optimized by adherence to a HAART regimen delivering virological suppression.

The impact of influenza A(H1N1)pdm09 infection on immunosuppressed patients

Before the advent of the influenza A(H1N1)pdm virus in 2009, the information available about the clinical manifestations and prognosis of influenza in immunosuppressed patients was scarce. With the 2009 pandemic, knowledge of the behavior, severity and importance of antiviral therapy for influenza A infection in immunocompromised hosts has increased considerably. The aim of the present manuscript is to review the main challenges of influenza in the most representative immunosuppressed populations such as solid organ transplant recipients, hematopoietic stem cell transplant recipients, patients with solid and hematological cancer and human immunodeficiency virus infected patients.

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.

Long-term follow-up in patients with HIV vaccinated with pandemic influenza A(H1N1)/09 AS03-adjuvanted split virion vaccine and seasonal trivalent influenza split virion vaccine

Introduction

In Sweden in 2009, two doses of the pandemic influenza A(H1N1)/09 AS03-adjuvanted split virion vaccine were recommended for those with HIV infection along with one dose of seasonal trivalent influenza vaccine (TIV). At that time, no data for HIV patients and their response to the adjuvanted vaccine were available.

Methods

Forty-two HIV-infected individuals were vaccinated with the pandemic vaccine on study days 0 and 28. Twenty-one of them received TIV on day 56 and 21 did not. Serum samples were taken at these time points, and also on day 86 and after 1 year for serologic analyses.

Results

Before vaccination, none of the 42 patients had putatively protective levels of antibodies (haemagglutination inhibition [HI] titres ≥1:40) to the pandemic-like strain A/California/7/2009 H1N1. After dose 1, the seroprotection rate (SPR) and seroconversion rate (SCR) were both 69% (29 of 42). After dose 2, the SPR and SCR were 89 and 86%, respectively. At 1 year, 10 (34%) of 29 had protective antibodies and 16 (62%) of 26 who had had protective antibody levels had lost them. There was a retained factor increase of the geometric mean titre (GMT) of 3.9.

Serological analyses could be performed in 19 subjects who were vaccinated with TIV and in 21 who were not. Protective antibodies to the three strains before vaccination were 20–37%. The SCR was 26% to A/Brisbane/59/2007 H1N1, 47% to A/Uruguay/10/2007/ H3N2 and 42% to B/Brisbane/60/2008. At 1 year, the factor increase of GMT was 1.8 to the two influenza A strains.

Conclusion

Two doses of adjuvanted influenza vaccine improved the SCR and the SPR among HIV-infected subjects. Long-term follow-up indicates revaccination in the next influenza season whether they received an adjuvanted or non-adjuvanted influenza vaccine.

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.

H1N1pdm09 adjuvanted vaccination in HIV-infected adults: a randomized trial of two single versus two double doses

Background

Since human immunodeficiency virus (HIV)-infected individuals are at increased risk of severe disease from pandemic influenza A (H1N1pdm09), vaccination was recommended as a prevention strategy. The aim of the present study was to evaluate the safety, immunogenicity and persistence of the immune response after vaccination against pandemic influenza A (H1N1pdm09) with an adjuvanted vaccine in human immunodeficiency virus (HIV)-infected adults using two single and two double doses.

Methodology/Principal Findings

Open label, randomized trial to evaluate the immune response following H1N1pdm09 vaccination in HIV-infected participants compared to HIV-negative controls (NCT01155037). HIV-infected participants were randomized to receive 2 single (3.75 µg hemagglutinin) or 2 double (7.5 µg hemagglutinin) doses of the vaccine, 21 days apart. Controls received one dose of the vaccine. The primary endpoint was seroconversion as measured by hemagglutination inhibition assay. Two hundred fifty six HIV-infected participants (129 and 127 randomized to single and double doses, respectively) and 71 HIV-negative controls were enrolled. Among HIV-infected participants, seroconversion increased from 46.7% and 51.7% after the first dose to 77.2% and 83.8% after the second dose of the vaccine using single and double doses, respectively. Participants aged >40 years showed higher seroconversion compared to younger participants. Seroconversion among HIV-infected women and those with nadir CD4<200 cells/mm³ was significantly higher with double doses. Persistence of protective antibodies six months after vaccination was achieved by 80% and 89.9% of the HIV-infected participants who received single and double doses, respectively.

Conclusions/Significance

Our results support the recommendation of two double doses of adjuvanted H1N1pdm09 vaccine for HIV-infected individuals, particularly women, and those aged >40 years or with nadir CD4<200 cells/mm³, to achieve antibody levels that are both higher and more sustained.

Trial Registration

ClinicalTrials.gov NCT01155037

Pandemic H1N12009 influenza and HIV: a review of natural history, management and vaccine immunogenicity

PURPOSE OF REVIEW

The 2009 pandemic HIN1 influenza strain (H1N12009) produced more severe disease and increased risk for mortality. As an at-risk population for more severe influenza illness, particular concern regarding HIV patients triggered a focused effort to evaluate disease burden and vaccine efficacy in these populations.

RECENT FINDINGS

As with other immune-compromised individuals, most HIV-infected individuals recovered without major consequence. Although HIV infection was assumed to be a risk factor for more severe disease and death, the published literature does not indicate this to be so. Neuraminadase inhibitors were well tolerated by this population and there was no evidence of clinically significant pharmacokinetic interactions with antiretroviral therapy. Immunogenicity was increased with H1N12009 vaccine compared to the historical results of nonpandemic vaccines and optimized by the use of adjuvants. Booster dosing was also of benefit. H1N12009 vaccine was generally well tolerated without evidence of detrimental effect on HIV status.

SUMMARY

The worse case scenario was not realized for H1N12009 in the general population or in those with HIV. Immunization with adjuvant represents a key measure to protect this population from H1N12009 and other future novel influenza strains.

Pulmonary manifestation of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients: initial findings with multidetector computed tomography

OBJECTIVE

To describe initial multidetector computed tomographic (MDCT) findings of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients and to evaluate whether or not identification of certain abnormalities can help predict patients who are at risk for a severe clinical course.

SUBJECTS AND METHODS

This retrospective study included 13 patients with confirmed S-OIV infection suffering from an underlying immunodeficiency or who were receiving immunosuppressive therapy. All patients underwent MDCT of the thorax due to respiratory distress. All data were read by two independent radiologists who described the type and pattern of opacities, distribution and extent of the abnormalities observed. Adverse outcome measures were defined as acute respiratory distress syndrome with the need for mechanical ventilation, extracorporeal membrane oxygenation or death.

RESULTS

MDCT revealed pulmonary manifestations in 12 (92%) of 13 individuals. Six (50%) patients showed an adverse outcome with development of acute respiratory distress syndrome, 4 of these died. The most common findings were ground-glass opacities (10/12; 83%) and pulmonary consolidation (7/12; 58%) predominantly with a bilateral distribution. Reticular pattern and a tree-in-bud appearance were found in 3/12 (25%), respectively. Bilateral opacities with extensive involvement of the lung parenchyma were most predictive of a severe clinical course.

CONCLUSION

The MDCT scan in immunocompromised patients with confirmed S-OIV infection frequently revealed pulmonary abnormalities, which included ground-glass opacities and consolidations. Therefore, prediction of an adverse clinical outcome could be made in patients with MDCT findings demonstrating bilateral extensive consolidations, often combined with ground-glass opacities.

Influenza and HIV: lessons from the 2009 H1N1 influenza pandemic

Influenza is a common respiratory disease in adults, including those infected with HIV. In the spring of 2009, a pandemic influenza A (H1N1) virus (pH1N1) emerged. In this article, we review the existing literature regarding pH1N1 virus infection in HIV-infected adults, which suggests that susceptibility to pH1N1 virus infection and severity of influenza illness are likely not increased in HIV-infected adults without advanced immunosuppression or comorbid conditions. The risk of influenza-related complications, however, may be increased in those with advanced immunosuppression or high-risk comorbid conditions. Prevention and treatment of high-risk comorbid conditions and annual influenza vaccination should continue to be part of HIV clinical care to help prevent influenza illness and complications. Additional information about pH1N1 vaccine immunogenicity and efficacy in HIV-infected patients would be useful to guide strategies to prevent influenza virus infection in this population.

The cost-effectiveness and value of information of three influenza vaccination dosing strategies for individuals with human immunodeficiency virus

Background

Influenza vaccine immunogenicity is diminished in patients living with HIV/AIDS. We evaluated the cost-effectiveness and expected value of perfect information (EVPI) of three alternative influenza vaccine dosing strategies intended to increase immunogenicity in those patients.

Methods

A randomized, multi-centered, controlled, vaccine trial was conducted at 12 CIHR Canadian HIV Trials Network sites. Three dosing strategies with seasonal, inactivated trivalent, non-adjuvanted intramuscular vaccine were used in HIV infected adults: two standard doses over 28 days (Strategy A), two double doses over 28 days (Strategy B) and a single standard dose of influenza vaccine (Strategy C), administered prior to the 2008 influenza season. The comparator in our analysis was practice in the previous year, in which 82.8% of HIV/AIDS received standard-dose vaccination (Strategy D). A Markov cohort model was developed to estimate the monthly probability of Influenza-like Illness (ILI) over one influenza season. Costs and quality-adjusted life years, extrapolated to the lifetime of the hypothetical study cohorts, were estimated in calculating incremental cost-effectiveness ratios (ICER) and EVPI in conducting further research.

Results

298 patients with median CD4 of 470 cells/µl and 76% with viral load suppression were randomized. Strategy C was the most cost-effective strategy for the overall trial population and for suppressed and unsuppressed individuals. Mean ICERs for Strategy A for unsuppressed patients could also be considered cost-effective. The level of uncertainty regarding the decision to implement strategy A versus C for unsuppressed individuals was high. The maximum acceptable cost of reducing decision uncertainty in implementing strategy A for individuals with unsuppressed pVL was $418,000 - below the cost of conducting a larger-scale trial.

Conclusion

Our results do not support a policy to implement increased antigen dose or booster dosing strategies with seasonal, inactivated trivalent, non-adjuvanted intramuscular vaccine for individuals with HIV in Canada.

Trial Registration

ClinicalTrials.gov NCT00764998.

A review of influenza vaccine immunogenicity and efficacy in HIV-infected adults

BACKGROUND

HIV-seropositive adults are at an increased risk for influenza infection. They also develop more severe influenza disease and are hyporesponsive to current influenza vaccinations.

METHODS

The authors examined findings from a systematic review of influenza vaccination in HIV-seropositive adults, and evaluated other relevant studies. A narrative overview of findings formulated to summarize the implications of currently available literature is presented. The primary goal of the present review is to assess the limitations of current evidence and to provide a framework for additional research.

RESULTS

There is a paucity of knowledge regarding the relative value of prophylactic influenza vaccination in HIV-positive adults compared with immunocompetent populations. There are shortcomings related to study methodology and temporal changes in the characteristics of patient baseline immune status, which limit the utility of this information to shape public health policy.

CONCLUSIONS

There is a pressing need to pursue methodologically rigorous studies that will increase knowledge related to improving the effectiveness of preventive influenza measures in this patient population.

Respiratory syncytial virus (RSV) community-acquired pneumonia (CAP) in a hospitalized adult with human immunodeficiency virus (HIV) mimicking influenza A and Pneumocystis (carinii) jiroveci pneumonia (PCP)

BACKGROUND

Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infections in young children, the elderly, and immunocompromised hosts, but RSV is a rare cause of community-acquired pneumonia (CAP) in hospitalized adults with human immunodeficiency virus (HIV). In patients with HIV, CAP is most frequently attributable to the usual bacterial respiratory pathogens that cause CAP in immunocompetent hosts, eg, Streptococcuspneumoniae or Hemophilus influenzae. Adults with HIV are also predisposed to intracellular CAP pathogens, ie, Mycoplasmatuberculosis, Salmonella spp., Pneumocystis (carinii) jiroveci (PCP), cytomegalovirus, and Legionella spp. This year, co-circulating in the community during influenza season were strains of human seasonal influenza A (H3N2) and swine influenza A (H1N1). During the influenza season, in adults hospitalized with HIV, the diagnostic possibilities should include influenza-like illnesses, eg, human parainfluenza virus types 3 and 4, human metapneumovirus, and pertussis.

CASE REPORT

We present an adult with HIV, hospitalized for an influenza-like illness during influenza season. The differential diagnosis of CAP in this patient included influenza A and PCP.

CONCLUSION

We report on an adult patient with HIV with CAP that mimicked influenza and PCP, and was attributable to RSV.

Immunogenicity and safety of monovalent influenza A (H1N1) 2009 in HIV-infected Thai children

To evaluate the immunogenicity and safety of the monovalent pandemic influenza A (H1N1) 2009 (pH1N1) vaccine in HIV-infected Thai children, 2 doses, 28days apart, of non-adjuvant monovalent pH1N1 vaccine (Panenza(®) by Sanofi Pasteur, 15μg/dose) provided by the National Health Promotion Program of the Thai Ministry of Public Health were given to HIV-infected children. Immunogenicity was measured by hemagglutination inhibition test (HAI) using two antigens, pH1N1 (A/Thailand/104/09) and seasonal influenza A H1N1 (A/Brisbane/59/07-like), at baseline, and 28days after each dose. Serologic response was defined as four-fold rising of HAI titer or HAI titer ≥1:40 for those with baseline titer ≤1:10. Adverse events were recorded for 7days after each vaccination. Of the 119 HIV-infected children enrolled, 60 (50.4%) were female with a median (IQR) age of 10.4 (7.2-13.7)years. All but 2 (98.3%) children were receiving antiretroviral therapy. At baseline, the median CD4 cell count was 782 (570-1149)cells/mm(3), 91 (80.5%) children had HIV RNA level <40copies/ml. The baseline HAI titer ≥1:40 for pH1N1 and seasonal H1N1 were 45.4%, and 39.5%, respectively. At 28 days after doses 1 and 2, the serologic response rates for pH1N1 were 54.2% and 67.8% with the geometric mean titer of 109.9 and 141.8; and serologic response rate when tested with seasonal H1N1 were 2.5% and 3.5%, respectively. The presence of baseline HAI titer for pH1N1 or seasonal H1N1 was found to be associated with serologic response. The vaccine was well tolerated. The results suggested that monovalent pH1N1 vaccine was immunogenic and safe in well controlled HIV-infected children with low level of cross reacting antibody to seasonal H1N1.

Innate immune defects correlate with failure of antibody responses to H1N1/09 vaccine in HIV-infected patients

BACKGROUND

Mechanisms underlying the failure of influenza vaccine-induced antibody responses in HIV-infected persons are poorly understood.

OBJECTIVE

To investigate innate immune factors regulating B-cell function in HIV-infected persons and to correlate them with serologic responses to H1N1/09 vaccine.

METHODS

We evaluated immunologic characteristics of 17 HIV-infected patients and 8 healthy controls (HCs) at 0, 7, and 28 days (designated T0, T1, and T2) following a single 15-μg dose of nonadjuvanted H1N1/09 influenza vaccine by using flow cytometry, ELISpot, and ELISA. All HCs and 9 patients (53%) seroconverted with >1:40 hemagglutination inhibition antibody titer at T2.

RESULTS

In vaccine responders and HCs, serum levels of BAFF (B cell-activating factor) and APRIL (a proliferation-inducing ligand) increased from T0 to T2 in conjunction with increases in frequencies of memory B cells. Concurrently, receptors for these factors showed changes, with increases in expression of TACI (transmembrane activator and calcium modulator and cyclophilin ligand interactor) and decreases in BAFF receptor in memory B cells. IL-2 secreting cells and IgG antibody-secreting cells increased at T2 in vaccine responders and HCs in ex vivo H1N1 antigen-stimulated cultures. These immunologic responses were not evident at T1 and were deficient in vaccine nonresponder patients at T2. At T0, vaccine nonresponders had lower frequencies of BAFF receptor and TACI-expressing memory B cells than did responders.

CONCLUSION

Impaired memory B-cell responses, deficiencies in serum BAFF and APRIL, and alterations in their receptors on B cells were associated with failure of H1N1/09 influenza vaccine responses among virologically controlled HIV-infected patients.

Reduced immune response to influenza A (H1N1) 2009 monovalent vaccine in HIV-infected Japanese subjects

We evaluated the immunogenicity and safety of the influenza A (H1N1) 2009 monovalent vaccine in HIV-infected Japanese subjects. A total of 182 HIV-infected and 42 HIV-uninfected subjects were enrolled, and antibody (ab) titers were measured by hemagglutination-inhibition assay at baseline and 32.3±10.4 and 29.7±3.3 days after vaccination, respectively. In the HIV-infected cohort, ab titers ≥ 1:40 at baseline and post-vaccination were 12.6% and 49.5%, respectively. The seroconversion rate, defined as either an ab titer ≤ 1:10 before and ≥ 1:40 after or ≥ 1:10 before and ≥ 4-fold increase in ab titer, was only 38.5% in the HIV-infected cohort, whereas the rate was 85.7% in the HIV-uninfected cohort. Multivariate logistic regression analysis showed that the CD4 cell count was the only significant predictor of a positive vaccine response. There were no serious adverse events in any of the subjects receiving the vaccine. Additional study is warranted to identify a more effective method of vaccinating HIV-infected Japanese subjects.

Pandemic Influenza A (H1N1) Infection among HIV-Infected Adults in France

Clinical, biological, and radiological findings of influenza A (H1N1)-confirmed cases among HIV-infected patients presenting in a French university hospital between October 2009 and January 2010 were systematically reviewed. No severe influenza infection was observed, but a high frequency of secondary bacterial pneumonia is reported among pneumococcal unvaccinated patients.

Influenza susceptibility, severity, and shedding in HIV-infected adults: a review of the literature

Influenza is a common cause of respiratory illness in adults infected with human immunodeficiency virus (HIV), but current knowledge about seasonal and 2009 H1N1 pandemic influenza A (H1N1pdm) virus infections in HIV-infected persons is limited. In this paper, we review the existing literature regarding influenza susceptibility, severity, and shedding in HIV-infected adults. Data show HIV infection does not significantly increase susceptibility to influenza. AIDS is associated with greater seasonal influenza-related morbidity and mortality, but the risk associated with HIV infection among those with less immune suppression is largely unknown. Immunologic compromise has been shown to increase the magnitude and duration of influenza virus shedding; however, these studies are limited within HIV-infected populations. With regards to H1N1pdm, data are even more limited. Reports raise concern of increased severity among HIV-infected persons, although this may be driven by other comorbid illnesses. Prospective studies are needed among HIV-infected persons to more definitively investigate influenza susceptibility, severity, and shedding.

Upregulation of IL-21 receptor on B cells and IL-21 secretion distinguishes novel 2009 H1N1 vaccine responders from nonresponders among HIV-infected persons on combination antiretroviral therapy

Mechanisms underlying failure of novel 2009 H1N1 influenza vaccine-induced Ab responses in HIV-infected persons are poorly understood. This study prospectively evaluated 16 HIV-infected patients on combination antiretroviral therapy and eight healthy controls (HC) who received a single 15 μg dose of nonadjuvanted novel 2009 H1N1 influenza vaccine during the 2009 H1N1 epidemic. Peripheral blood was collected at baseline (T0) and at 7 d (T1) and 28 d (T2) postvaccination for evaluation of immune responses. Prevaccination hemagglutination inhibition Ab titer was <1:20 in all except one study participant. At T2, all HC and 8 out of 16 patients (50%) developed a vaccine-induced Ab titer of ≥ 1:40. Vaccine responder (R) and vaccine nonresponder patients were comparable at T0 in age, CD4 counts, virus load, and B cell immunophenotypic characteristics. At T2, HC and R patients developed an expansion of phenotypic and functional memory B cells and ex vivo H1N1-stimulated IgG Ab-secreting cells in an ELISPOT assay. The memory B cell response was preceded by a significant expansion of plasmablasts and spontaneous H1N1-specific Ab-secreting cells at T1. At T2, HC and R patients also exhibited significant increases in serum IL-21 levels and in the frequency and mean fluorescence intensity of IL-21R-expressing B cells, which correlated with serum H1N1 Ab titers. Vaccine nonresponder patients failed to develop the above-described vaccine-induced immunologic responses. The novel association of novel 2009 H1N1 vaccine-induced Ab responses with IL-21/IL-21R upregulation and with development of memory B cells and plasmablasts has implications for future research in vaccine design.

Immunogenicity is not improved by increased antigen dose or booster dosing of seasonal influenza vaccine in a randomized trial of HIV infected adults

INTRODUCTION

The risk of poor vaccine immunogenicity and more severe influenza disease in HIV necessitate strategies to improve vaccine efficacy.

METHODS

A randomized, multi-centered, controlled, vaccine trial with three parallel groups was conducted at 12 CIHR Canadian HIV Trials Network sites. Three dosing strategies were used in HIV infected adults (18 to 60 years): two standard doses over 28 days, two double doses over 28 days and a single standard dose of influenza vaccine, administered prior to the 2008 influenza season. A trivalent killed split non-adjuvanted influenza vaccine (Fluviral™) was used. Serum hemagglutinin inhibition (HAI) activity for the three influenza strains in the vaccine was measured to assess immunogenicity.

RESULTS

297 of 298 participants received at least one injection. Baseline CD4 (median 470 cells/µL) and HIV RNA (76% of patients with viral load <50 copies/mL) were similar between groups. 89% were on HAART. The overall immunogenicity of influenza vaccine across time points and the three influenza strains assessed was poor (Range HAI ≥ 40 =  31-58%). Double dose plus double dose booster slightly increased the proportion achieving HAI titre doubling from baseline for A/Brisbane and B/Florida at weeks 4, 8 and 20 compared to standard vaccine dose. Increased immunogenicity with increased antigen dose and booster dosing was most apparent in participants with unsuppressed HIV RNA at baseline. None of 8 serious adverse events were thought to be immunization-related.

CONCLUSION

Even with increased antigen dose and booster dosing, non-adjuvanted influenza vaccine immunogenicity is poor in HIV infected individuals. Alternative influenza vaccines are required in this hyporesponsive population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00764998.

Induction of protective antibody response by MF59-adjuvanted 2009 pandemic A/H1N1v influenza vaccine in HIV-1-infected individuals

OBJECTIVE

to determine the immunogenicity of the monovalent vaccine against 2009 pandemic influenza A/H1N1 in HIV-1-infected individuals.

DESIGN

a total of 192 participants, including 44 HIV-1-positive individuals and 148 HIV-1-negative healthy controls were enrolled to receive a single dose of MF59-adjuvanted 2009 A/H1N1v vaccine formulated to contain 7.5 microg of haemagglutin antigen.

METHODS

standard haemagglutination inhibition (HAI) assay was performed to evaluate seroconversion and seroprotecsion rates against the pandemic virus in serum samples collected at baseline (T0) and 3-5-week postvaccination (T28). Seroconversion to vaccination was defined by either prevaccination HAI titer less than 1: 10 with a postvaccination titer higher than 1: 40, or a prevaccination titer higher than 1: 10 and increase of at least four-fold or more after vaccination. Seroprotection was defined by HAI titers higher than 1: 40.

RESULTS

the vaccine induced specific antibody titers in HIV-1-positive individuals similar to those of HIV-1-negative controls [215.3, 95% confidence interval (CI) 150.4-308.1 vs. 275.9, 95% CI 232.6-327.3] with postvaccination seroprotection rates higher than 97%. In contrast, the seroconversion rate was lower in the HIV-1-positive individuals as compared with the HIV-1-negative controls (36.4 vs. 79.0%, P < 0.0001), likely as a consequence of their high HAI baseline titers. Multivariable logistic regression analysis showed that seroconversion was less likely in HIV-1-positive individuals [odds ratio (OR) = 0.237, 95% CI 0.104-0.539, P = 0.0006) and with increasing age (OR = 0.805, 95% CI 0.684-0.947, P = 0.009).

CONCLUSIONS

a single dose of MF59-adjuvanted 2009 influenza H1N1 vaccine induced an immune response against pandemic H1N1 virus in HIV-1-positive individuals reaching titers similar to those of HIV-1-negative individuals. The seroconversion rate was negatively associated with HIV infection and increasing age.