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

A review of criteria strictness in "Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventive Vaccine Clinical Trials"

To assess safety in vaccine development, stricter grading scales, such as the "Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventive Vaccine Clinical Trials" issued by the U.S. Food and Drug Administration (FDA grading scale), are required. However, concern exists that their strictness may lead to an overestimation of some adverse events (AEs). We analyzed the details of AEs in a phase I clinical trial of a preventive vaccine for infectious diseases. In this trial, we observed the high occurrence of Grade 1 or greater AEs in hemoglobin changes from baseline value, and hypernatremia, and hypokalemia by FDA grading scale. The range considered as non-AE according to the FDA grading scale shifted or became narrower when compared to reference intervals, especially for a Japanese cohort. For sodium grading, the criterion for hypernatremia was around 2 to mEq/L lower than the upper limit of most standards in several countries. Also, the criterion for hypokalemia was around 0.2 mEq/L higher than the lower limit of most standards. Regarding a decrease in hemoglobin from baseline, the criterion of "any decrease" used for a Grade 1 AE was too strict and we suggest this be omitted. Upper and lower limits of AE criteria for sodium and potassium should be equal to, or 10-20% above, the reference interval consistent with other toxicities determined by laboratory tests. Consideration should be given to the issues surrounding the criteria that determine AEs before conducting clinical trials.

Summary of the National Advisory Committee on Immunization (NACI) Statement-Recommendations on Fractional Influenza Vaccine Dosing in the Event of a Shortage: Pandemic preparedness

Background

At the commencement of a pandemic, it is important to consider the impact of respiratory infections on the health system and the possibility of vaccine shortages due to increased demand. In the event of an influenza vaccine shortage, a strategy for administration of fractional influenza vaccine doses might be considered. This article reviews the available evidence for efficacy, effectiveness, immunogenicity and safety of fractional influenza vaccine dosing, and summarizes the National Advisory Committee on Immunization (NACI) recommendations on fractional dosing strategies by public health programs in Canada.

Methods

Two rapid literature reviews were undertaken to evaluate the efficacy, effectiveness, immunogenicity and safety of fractional influenza vaccine dosing via the intramuscular or intradermal route. The NACI evidence-based process was used to assess the quality of eligible studies, summarize and analyze the findings, and apply an ethics, equity, feasibility and acceptability lens to develop recommendations.

Results

There was limited evidence for the effectiveness of fractional influenza vaccine dosing. Fractional dosing studies were primarily conducted in healthy individuals, mainly young children and infants, with no underlying chronic conditions. There was fair evidence for immunogenicity and safety. Feasibility issues were identified with intradermal use in particular.

Conclusion

NACI recommended that, in the event of a significant population-level shortage of influenza vaccine, a full-dose influenza vaccine should continue to be used, and existing vaccine supply should be prioritized for those considered to be at high risk or capable of transmitting to those at high risk of influenza-related complications or hospitalizations. NACI recommended against the use of fractional doses of influenza vaccine in any population.

High seroprotection rates and geometric mean titre increases after repeated annual influenza vaccinations in a cohort of HIV-infected adults in Austria

INTRODUCTION

Vaccination against seasonal influenza is recommended for all HIV-infected persons. Few data have been reported on the effect of repeated annual vaccination in this population.

METHODS

We measured haemagglutination inhibition antibody responses and investigated seroprotection rates in 344 HIV-infected adults before and 12 weeks after influenza vaccination with a trivalent subunit vaccine.

RESULTS

68.3% of patients were male, the median age was 45 years. 83.7% had a viral load < 50 copies/mL. The median CD4 count was 604/µL. 304 patients (88.4%) had received influenza vaccinations in previous years. Seroprotection rates for A/H1N1 and B were over 90% in all age groups before vaccination and close to 100% after vaccination. For A/H3N2, seroprotection rates were lowest in individuals below 30 years both before and after vaccination (22.2% and 50.0%) and higher in older age groups (48.4% and 83.9% in people over 60 years). GMT fold increases were not significantly different across the age groups (3.0 to 4.2, p = 0.425). Previous influenza vaccinations were associated with higher seroprotection rates before and after vaccination (62.2% and 84.2% in patients with 8 or more previous vaccinations vs. 15.0% and 57.5% without previous vaccinations, respectively). Individuals with detectable viral load, elevated immune activation (urine neopterin ≥ 250 µmol/mol creatinine), and higher CD4 nadir (≥200 cells/µL) showed a trend towards inferior immune responses to vaccination, whereas gender and CD4 count did not have an effect.

CONCLUSION

The lower seroprotection rates observed in younger individuals may be explained by the higher proportion of patients without HIV treatment and with fewer previous encounters with influenza strains. Good seroprotection rates can be achieved in elderly HIV-infected patients and after repeated annual vaccinations.

Post-Exposure Prophylactic Vaccination against Rabies: A Systematic Review

BACKGROUND

Post-exposure prophylaxis (PEP) is an effective method for preventing rabies, a highly fatal infection in exposed persons. Malaysia is currently using the purified Vero cell rabies vaccine (PVRV). Nonetheless, there are other commercially available vaccine types and regimens. This systematic review aimed at comparing the effectiveness of the different PEP vaccines, regimens and routes of administration among Asian populations.

METHODS

We systematically reviewed the PubMed and Web of Science databases for articles reporting on the effectiveness of PEP vaccination against rabies among Asian populations between 2015 and 2019.

RESULTS

Our search identified 11 relevant studies. Majority of study either used PCECV or PVRV type of vaccine, with different regimes and method. All are non-inferior to the other. Most of the studies recorded adequate response by Day 14 of vaccination. Nonetheless, the intradermal (ID) vaccination used minimal volume of vaccine used in all settings, thus cost less and the concurrent administration of RIG to the wound(s) doesn't affect the RVNA GMT response.

CONCLUSION

PCECV, using either the Essen or Zagreb regimen, might be a useful alternative for the healthy population in the context of PVRV shortage, especially during an outbreak. Use of the Zagreb or Thai Red Cross (TRC) regimens can be considered (either PVRV or PCECV), as both demonstrate good immunogenic outcomes in Asian populations.

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.

Immunogenicity and Safety of Reduced-Dose Intradermal vs Intramuscular Influenza Vaccines: A Systematic Review and Meta-analysis

IMPORTANCE

Low-dose intradermal influenza vaccines could be a suitable alternative to full intramuscular dose during vaccine shortages.

OBJECTIVE

To compare the immunogenicity and safety of the influenza vaccine at reduced or full intradermal doses with full intramuscular doses to inform policy design in the event of vaccine shortages.

DATA SOURCES

MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched for studies published from 2010 until June 5, 2020.

STUDY SELECTION

All comparative studies across all ages assessing the immunogenicity or safety of intradermal and intramuscular influenza vaccinations were included.

DATA EXTRACTION AND SYNTHESIS

Data were extracted by a single reviewer and verified by a second reviewer. Discrepancies between reviewers were resolved through consensus. Random-effects meta-analysis was conducted.

MAIN OUTCOMES AND MEASURES

Primary outcomes included geometric mean titer, seroconversion, seroprotection, and adverse events.

RESULTS

A total of 30 relevant studies were included; 29 studies were randomized clinical trials with 13 759 total participants, and 1 study was a cohort study of 164 021 participants. There was no statistically significant difference in seroconversion rates between the 3-µg, 6-µg, 7.5-µg, and 9-µg intradermal vaccine doses and the 15-µg intramuscular vaccine dose for each of the H1N1, H3N2, and B strains, but rates were significantly higher with the 15-µg intradermal dose compared with the 15-µg intramuscular dose for the H1N1 strain (rate ratio [RR], 1.10; 95% CI, 1.01-1.20) and B strain (RR, 1.40; 95% CI, 1.13-1.73). Seroprotection rates for the 9-µg and 15-µg intradermal doses did not vary significantly compared with the 15-µg intramuscular dose for all the 3 strains, except for the 15-µg intradermal dose for the H1N1 strain, for which rates were significantly higher (RR, 1.05; 95% CI, 1.01-1.09). Local adverse events were significantly higher with intradermal doses than with the 15-µg intramuscular dose, particularly erythema (3-µg dose: RR, 9.62; 95% CI, 1.07-86.56; 6-µg dose: RR, 23.79; 95% CI, 14.42-39.23; 9-µg dose: RR, 4.56; 95% CI, 3.05-6.82; 15-µg dose: RR, 3.68; 95% CI, 3.19-4.25) and swelling (3-µg dose: RR, 20.16; 95% CI, 4.68-86.82; 9-µg dose: RR, 5.23; 95% CI, 3.58-7.62; 15-µg dose: RR, 3.47 ; 95% CI, 2.21-5.45). Fever and chills were significantly more common with the 9-µg intradermal dose than the 15-µg intramuscular dose (fever: RR, 1.36; 95% CI, 1.03-1.80; chills: RR, 1.24; 95% CI, 1.03-1.50) while all other systemic adverse events were not statistically significant for all other doses.

CONCLUSIONS AND RELEVANCE

These findings suggest that reduced-dose intradermal influenza vaccination could be a reasonable alternative to standard dose intramuscular vaccination.

Travel vaccination recommendations and infection risk in HIV-positive travellers

BACKGROUND

With the advent of highly active antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) it has become possible for people with HIV to travel to destinations that may place them at risk of a number of infectious diseases. Prevention of infections by vaccination is therefore of paramount importance for these travellers. However, vaccine responsiveness in HIV-positive individuals is not infrequently reduced compared to HIV-negative individuals. An understanding of the expected immune responses to vaccines in HIV-positive travellers is therefore important in planning the best approach to a pretravel consultation.

METHODS

A PubMed search was performed on HIV or acquired immune deficiency syndrome together with a search for specific vaccines. Review of the literature was performed to develop recommendations on vaccinations for HIV-positive travellers to high-risk destinations.

RESULTS

The immune responses to several vaccines are reduced in HIV-positive people. In the case of vaccines for hepatitis A, hepatitis B, influenza, pneumococcus, meningococcus and yellow fever there is a good body of data in the literature showing reduced immune responsiveness and also to help guide appropriate vaccination strategies. For other vaccines like Japanese encephalitis, rabies, typhoid fever, polio and cholera the data are not as robust; however, it is still possible to gain some understanding of the reduced responses seen with these vaccines.

CONCLUSION

This review provides a summary of the immunological responses to commonly used vaccines for the HIV-positive travellers. This information will help guide travel medicine practitioners in making decisions about vaccination and boosting of travellers with HIV.

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.

Rabies post-exposure prophylaxis: A systematic review on abridged vaccination schedules and the effect of changing administration routes during a single course

Rabies is a fatal zoonotic disease preventable through timely and adequate post-exposure prophylaxis (PEP) to potentially exposed persons i.e. wound washing and antisepsis, a series of intradermal (ID) or intramuscular (IM) rabies vaccinations, and rabies immunoglobulin in WHO category III exposures. The 2010 WHO position on rabies vaccines recommended PEP schedules requiring up to 5 clinic visits over the course of approximately one month. Abridged schedules with less doses have potential to save costs, increase patient compliance, and thereby improve equitable access to life-saving PEP for at-risk populations. We systematically reviewed new evidence since that considered for the 2010 position paper to evaluate (i) the immunogenicity and effectiveness of PEP schedules of reduced dose and duration; (ii) new evidence on effective PEP protocols for special populations; and (iii) the effect of changing routes of administration (ID or IM) during a single course of PEP. Our search identified a total of 14 relevant studies. The identified studies supported a reduction in dose or duration of rabies PEP schedules. The 1-week, 2-site ID PEP schedule was found to be most advantageous, as it was safe, immunogenic, supported by clinical outcome data and involved the least direct costs (i.e. cost of vaccine) compared to other schedules. To supplement this evidence, as yet unpublished additional data were reviewed to support the strength of the recommendations. Evidence suggests that changes in the rabies vaccine product and/or the route of administration during PEP is possible. Few studies have evaluated PEP schedules in persons with suspect or confirmed rabies exposures. Gaps exist in understanding the safety and immunogenicity of novel PEP schedules in special populations such as infants and immunocompromised individuals. Available data indicate that administering rabies vaccines during pregnancy is safe and effective.

Influenza Vaccination in Patients with Common Variable Immunodeficiency (CVID)

PURPOSE OF REVIEW

Vaccination against influenza in patients with primary antibody deficiency is recommended. Common variable immunodeficiency (CVID) is the most frequent and clinically relevant antibody deficiency disease and is by definition characterized by an impaired vaccination response. The purpose of this review is to present the current knowledge of humoral and cellular vaccine response to influenza in CVID patients.

RECENT FINDINGS

Studies conducted in CVID patients demonstrated an impaired humoral response upon influenza vaccination. Data on cellular immune response are in part conflicting, with two out of three studies showing responses similar to healthy controls. Available data suggest a benefit from influenza vaccination in CVID patients. Therefore, annual influenza vaccination in patients and their close household contacts is recommended.