Immune response to co-administration of measles, mumps, and rubella (MMR), and yellow fever vaccines: a randomized non-inferiority trial among one-year-old children in Argentina

Immunogenicity of yellow fever vaccine co-administered with 13-valent pneumococcal conjugate vaccine in rural Gambia: A cluster-randomised trial

INTRODUCTION

Because booster doses of pneumococcal conjugate vaccine (PCV) may be given at a similar time to yellow fever vaccine (YF), it is important to assess the immune response to YF when co-administered with PCV. This has been investigated during a reduced-dose PCV trial in The Gambia.

METHODS

In this phase 4, parallel-group, cluster-randomized trial, healthy infants aged 0-10 weeks were randomly allocated to receive either a two-dose schedule of PCV13 with a booster dose co-administered with YF vaccine at age 9 months (1 + 1 co-administration) or YF vaccine administered separately at age 10 months (1 + 1 separate) or the standard three early doses of PCV13 with YF vaccine at age 9 months (3 + 0 separate). Blood samples were collected 28-35 days post-vaccination and YF neutralizing antibody (NA) titres were measured. Proportions with seroprotective YF NA titres ≥ 1:8 were calculated with 95 % confidence intervals (CI). Non-inferiority was demonstrated if the lower limit of the CI for the difference in proportions between the co-administration and separate groups was greater than - 10 %.

RESULTS

Forty-eight, 66, and 98 participants enrolled in 3 + 0 separate, 1 + 1 co-administration, and 1 + 1 separate groups respectively had NA results. Per protocol analysis of the 3 + 0 separate, 1 + 1 co-administration, 1 + 1 separate, and the combined 1 + 1 separate and 3 + 0 separate groups found that 81 %, 85 %, 92 %, and 88 % of participants respectively had YF NA titres ≥1:8. Results were similar with analysis by intention-to-treat. The difference in proportions comparing 1 + 1 co-administration and 1 + 1 separate groups was -7 % (95 % CI, -18 % to 3 %). The difference between 1 + 1 co-administration and 3 + 0 separate groups was 4 % (95 % CI, -10 % to 15 %). There was no statistical difference in the YF seroresponse when the YF vaccine was co-administered with PCV or administered separately.

CONCLUSIONS

No evidence was found of the non-inferiority of the seroresponse to YF vaccine when co-administered with PCV13. The levels of YF NA attaining seroprotection (NT ≥1:8) were high in all groups. PCV13 co-administered with YF vaccine at 9 months does not affect seroresponse to YF vaccine. http://www.isrctn.org/ - ISRCTN72821613.

Immunization in women's lives: present and future

•The negative impact of infectious diseases and their immunoprevention during the different stages of a woman's life requires a broad approach including adolescence, adulthood, pregnancy and the postmenopausal phase. •Immunization of pregnant women should be a priority for the protection of the maternal-fetal dyad, especially in regions with high rates of infections preventable by immunization. •Brazil has one of the most comprehensive vaccination programs in the world - the National Immunization Program (Programa Nacional de Imunizações, PNI) - that serves all age groups: newborns, children, adolescents, adults, pregnant women and older adults, as well as groups with special needs, such as adolescents, pregnant and older adult women. •However, vaccination coverage remains below ideal for all available vaccines, especially among adolescents and pregnant women, and Febrasgo is committed to collaborating with the PNI to combat vaccine hesitancy. •The gynecologist/obstetrician is the reference physician for women, therefore the access to information and updates regarding all vaccines recommended for their patients is extremely important for this professional, aiming at the greatest possible protection. •The objective of this Febrasgo Position Statement is to bring an update to women's vaccination schedule, covering some vaccines that are available, including new approved vaccines and those in the commercialization phase. •This work is a compilation of the First Febrasgo Scientific Immunization Forum held in the city of São Paulo in October 2023 with the objective to update recommendations for vaccines in use and new innovative vaccines soon to be available.

Humoral immunogenicity of primary yellow fever vaccination in infants and children: a systematic review, meta-analysis and meta-regression

BACKGROUND

Vaccination plays a critical role in mitigating the burden associated with yellow fever (YF). However, there is a lack of comprehensive evidence on the humoral response to primary vaccination in the paediatric population, with several questions debated, including the response when the vaccine is administered at early ages, the effect of co-administration with other vaccines, the duration of immunity and the use of fractional doses, among others. This study summarizes the existing evidence regarding the humoral response to primary YF vaccination in infants and children.

METHODS

Studies on the humoral response to primary YF vaccination in children aged 12 years or younger were reviewed. The humoral vaccine response rate (VRR), i.e. the proportion of children who tested positive for vaccine-induced YF-specific neutralizing antibodies, was pooled through random-effects meta-analysis and categorized based on the time elapsed since vaccination. Subgroup, meta-regression and sensitivity analyses were performed.

RESULTS

A total of 33 articles met the inclusion criteria, with all but one conducted in countries where YF is endemic. A total of 14 028 infants and children entered this systematic review. Within three months following vaccination, the pooled VRR was 91.9% (95% CI 89.8-93.9). A lower VRR was observed with the 17DD vaccine at the meta-regression analysis. No significant differences in immunogenicity outcomes were observed based on age, administration route, co-administration with other vaccines, or fractional dosing. Results also indicate a decline in VRR over time.

CONCLUSIONS

Primary YF vaccination effectively provides humoral immunity in paediatric population. However, humoral response declines over time, and this decline is observable after the first 18 months following vaccination. A differential response according to the vaccine substrain was also observed. This research has valuable implications for stimulating further research on the primary YF vaccination in infants and children, as well as for informing future policies.