Seroconversion and antibody persistence after yellow fever vaccination in people living with HIV: impact of baseline HIV viral load and yellow fever seropositivity

Yellow fever neutralizing antibody seroprevalence proportion and titers in previously vaccinated adults with chronic kidney disease

Studies on yellow fever vaccine (YF) in chronic kidney disease (CKD) patients are scarce. This cross-sectional study aimed to evaluate YF neutralizing antibody seroprevalence and titers in previously vaccinated adults with CKD, on dialysis (D-CKD) or not (ND-CKD), compared to healthy persons. The micro Plaque Reduction Neutralization-Horseradish Peroxidase (μPRN-HP) test was used. Antibody titers were expressed as the reciprocal of the highest dilution that neutralized the challenge virus by 50 % (μPRN50). Seropositivity cut-off was set at ≥ 1:100. We included 153 participants: 46 ND-CKD, 50 D-CKD and 57 healthy adults. Median ages were 58.3, 55 and 52.2 years, respectively. Median time since YF vaccination was 22.3, 18.5 and 48.3 months respectively. There were no statistically significant differences in YF seroprevalence and neutralizing antibodies titers among groups: 100 % of ND-CKD; 96 % of D-CKD and 100 % of healthy participants were seropositive. Geometric mean titers (GMT) were 818.5, 683.0 and 665.5, respectively (p = 0.289).

Long-term immunity following yellow fever vaccination: a systematic review and meta-analysis

BACKGROUND

Long-term immunity following yellow fever vaccination remains controversial. We aimed to summarise the literature regarding the long-term protection (≥10 years) conveyed by a single dose of yellow fever vaccination.

METHODS

In this systematic review and meta-analysis, we searched 11 databases from database inception to Aug 24, 2023. We included cohort and cross-sectional studies reporting immunogenicity outcomes for children or adults who received a single dose of yellow fever vaccination 10 or more years ago. Case series and single case reports were excluded. Participants who received more than one dose of yellow fever vaccination before measurement of the outcome were excluded. Identified records were reviewed by two independent reviewers. The primary outcome of the meta-analysis was the pooled seroprotection rate. Risk of bias was assessed with the Risk Of Bias In Non-randomized Studies of Interventions tool, and the Joanna Briggs Institute tool for analytical cross-sectional studies. Studies of moderate or good quality that reported seroprotection were included for random-effects meta-analysis and stratified by endemicity and specific risk groups. The study was registered with PROSPERO, CRD42023384087.

FINDINGS

Of the 7363 articles identified by our search, 39 were eligible for inclusion for systematic review. These studies comprised 2895 individuals vaccinated 10-60 years ago. 20 studies were included in the meta-analysis. Pooled seroprotection rates were 94% (95% CI 86-99) among healthy adults in a non-endemic setting (mostly travellers) and 76% (65-85) in an endemic setting (all Brazilian studies). The pooled seroprotection rate was 47% (35-60) in children (aged 9-23 months at time of vaccination) and 61% (38-82) in people living with HIV. Reported criteria for seroprotection were highly heterogeneous.

INTERPRETATION

The gathered evidence suggests that a single dose of yellow fever vaccination provides lifelong protection in travellers. However, in people living with HIV and children (younger than 2 years), booster doses might still be required because lower proportions of vaccinees were seroprotected 10 or more years post-vaccination. Lower observed seroprotection rates among residents of endemic areas were partly explained by the use of a higher cutoff for seroprotection that was applied in Brazil. Studies from sub-Saharan Africa were scarce and of low quality; thus no conclusions could be drawn for this region.

FUNDING

None.

Immunogenicity and safety of fractional doses of 17D-213 yellow fever vaccine in HIV-infected people in Kenya (YEFE): a randomised, double-blind, non-inferiority substudy of a phase 4 trial

BACKGROUND

Evidence indicates that fractional doses of yellow fever vaccine are safe and sufficiently immunogenic for use during yellow fever outbreaks. However, there are no data on the generalisability of this observation to populations living with HIV. Therefore, we aimed to evaluate the immunogenicity of fractional and standard doses of yellow fever vaccine in HIV-positive adults.

METHODS

We conducted a randomised, double-blind, non-inferiority substudy in Kilifi, coastal Kenya to compare the immunogenicity and safety of a fractional dose (one-fifth of the standard dose) versus the standard dose of 17D-213 yellow fever vaccine among HIV-positive volunteers. HIV-positive participants aged 18-59 years, with baseline CD4+ T-cell count of at least 200 cells per mL, and who were not pregnant, had no previous history of yellow fever vaccination or infection, and had no contraindication for yellow fever vaccination were recruited from the community. Participants were randomly assigned 1:1 in blocks (variable block sizes) to either a fractional dose or a standard dose of the 17D-213 yellow fever vaccine. Vaccines were administered subcutaneously by an unblinded nurse and pharmacist; all other study personnel were blinded to the vaccine allocation. The primary outcome of the study was the proportion of participants who seroconverted by the plaque reduction neutralisation test (PRNT50) 28 days after vaccination for the fractional dose versus the standard dose in the per-protocol population. Secondary outcomes were assessment of adverse events and immunogenicity during the 1-year follow-up period. Participants were considered to have seroconverted if the post-vaccination antibody titre was at least 4 times greater than the pre-vaccination titre. We set a non-inferiority margin of not less than a 17% decrease in seroconversion in the fractional dose compared with the standard dose. This study is registered with ClinicalTrials.gov, NCT02991495.

FINDINGS

Between Jan 29, 2019, and May 17, 2019, 303 participants were screened, and 250 participants were included and vaccinated; 126 participants were assigned to the fractional dose and 124 to the standard dose. 28 days after vaccination, 112 (96%, 95% CI 90-99) of 117 participants in the fractional dose group and 115 (98%, 94-100) of 117 in the standard dose group seroconverted by PRNT50. The difference in seroconversion between the fractional dose and the standard dose was -3% (95% CI -7 to 2). Fractional dosing therefore met the non-inferiority criterion, and non-inferiority was maintained for 1 year. The most common adverse events were headache (n=31 [12%]), fatigue (n=23 [9%]), myalgia (n=23 [9%]), and cough (n=14 [6%]). Reported adverse events were either mild (182 [97%] of 187 adverse events) or moderate (5 [3%]) and were self-limiting.

INTERPRETATION

Fractional doses of the 17D-213 yellow fever vaccine were sufficiently immunogenic and safe demonstrating non-inferiority to the standard vaccine dose in HIV-infected individuals with CD4+ T cell counts of at least 200 cells per mL. These results provide confidence that fractional dose recommendations are applicable to populations with high HIV prevalence.

FUNDING

Wellcome Trust, Médecins Sans Frontières Foundation, and the UK Department for International Development.

Do people living with HIV travel safely? Assessment of travel patterns and advice-seeking behaviour in a cohort of people living with HIV in Belgium

OBJECTIVES

Pre-travel counselling has demonstrated its efficacy in decreasing travel-related health complications. The current profile of people living with HIV (PLWH) in Europe [increasing age, visiting friends and relatives (VFR)] makes pre-travel counselling crucial. We aimed to survey the self-reported travel patterns and advice-seeking behaviour among PLWH followed up at the HIV Reference Centre (HRC) of Saint-Pierre Hospital, Brussels.

METHODS

A survey was conducted in all PLWH presenting at the HRC from February to June 2021. The survey covered demographic elements, travel and pre-travel consultation habits over the last 10 years, or since the diagnosis of HIV if it was made less than 10 years earlier.

RESULTS

The survey was completed by 1024 PLWH (35% women, median age 49 years, the majority being virologically controlled). A substantial number of PLWH were involved in VFR travel in low-resource countries and 65% sought pre-travel advice before travelling: if not, it was because they did not know it was necessary (91%).

CONCLUSION

Travel is common among PLWH. Raising awareness of the importance of pre-travel counselling should be a routine part of every healthcare encounter and especially during regular contact with HIV physicians.

SARS-CoV-2 Seropositivity and HIV Viral Load Among Mozambican Pregnant Women

INTRODUCTION

Prevalence estimates of SARS-CoV-2 infection in Africa are limited, particularly among pregnant women and in those living with HIV. This study assessed the seroprevalence of SARS-CoV-2 antibodies among Mozambican HIV-infected pregnant women during the first year of the pandemic, before COVID-19 vaccines were deployed in the country.

SETTING

The study was conducted in Manhiça district, a semirural area in southern Mozambique.

METHODS

A prospective cohort study including pregnant women living with HIV was conducted from November 2019 to June 2021. Women were enrolled at the first antenatal care clinic visit and followed until postpartum. HIV viral load and IgM/IgG antibodies against SARS-CoV-2 were determined in blood samples at first antenatal care clinic visit and at delivery. Associations between SARS-CoV-2 serostatus and maternal characteristics at enrolment were analyzed.

RESULTS

A total of 397 women were enrolled. SARS-CoV-2 IgG/IgM antibodies were detected in 7.1% of women at enrolment and in 8.5% of women at delivery. Overall, SARS-CoV-2 antibodies were detected in 45 women (11.3%; 95% confidence interval 8.4 to 14.9%) during the study period; the first seropositive sample was identified in September 2020. Having undetectable HIV viral load was associated with seropositivity of SARS-CoV-2 IgG/IgM [odds ratio 3.35 (1.10 to 11.29); P = 0.039].

CONCLUSION

Seroprevalence of SARS-CoV-2 antibodies in this cohort of Mozambican unvaccinated pregnant women was similar to reported global estimates of approximately 10% in pregnancy for 2021. The findings also suggest that pregnant women with high HIV viral load may have an impaired immune response against SARS-CoV-2 and might need to be carefully managed in case of COVID-19.

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

OBJECTIVES

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

DESIGN

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

METHODS

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

RESULTS

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

CONCLUSIONS

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