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.

Respiratory Syncytial Virus (RSV) and Intention to Recommend RSV Vaccination: A Cross-Sectional Survey of Cardiologists and Cardiac Nurses in Southern Italy

As respiratory syncytial virus (RSV) vaccine distribution gains traction in Europe and Italy, healthcare workers (HCWs) can strategize about vaccine promotion to increase uptake among patients at risk of RSV consequences, such cardiac patients. This cross-sectional survey investigated the knowledge about and attitude towards RSV and RSV vaccines, and the intention to recommend vaccination within a cardiological hospital in Italy. To explore factors associated with the outcomes of interest, multivariate logistic regression analyses were conducted. Of 197 invited HCWs, 78.2% returned the survey. The knowledge about market authorisation for new RSV vaccines for older adults (present in 46.9% of respondents) was significantly associated with the HCWs' age, education, and previous update on vaccinations. HCWs with a higher educational level and those with a positive attitude towards RSV vaccines safety reported a higher attitude towards the importance of vaccinating people at risk. The willingness of recommending RSV vaccination to patients (70.5% of respondents) was more likely in HCWs who were knowledgeable about market authorisation for RSV vaccines and in physicians. This tempestive research sheds light on current factors influencing the strategies of cardiac HCWs regarding RSV vaccination. The results suggest the need for training events on the protective role of RSV vaccination in cardiac patients.

Knowledge, Attitudes and Practices Survey of Recombinant Zoster Vaccine among Cardiologists and Cardiac Nurses in Italy

Background and Objectives: Cardiac patients are particularly at risk of herpes zoster (HZ), which is associated with a higher risk of major cardiovascular events. This research aimed to analyze the knowledge, attitudes and practices towards recombinant zoster vaccine (RZV) among cardiac healthcare professionals (HPs). Materials and Methods: A cross-sectional survey was conducted in a cardiological hospital in Italy. Multivariate regression models were built to identify factors associated with the outcomes of interest. Results: The response rate was 78.2% (154/197). Overall, age > 50 years and immunosuppression were recognized as risk factors for HZ by 38.3% and 75.3% of respondents, respectively. Regarding RZV, 29.1% of the HPs correctly responded about its schedule and 57.6% about the possibility of administration in immunocompromised individuals. This knowledge was significantly higher in HPs with a higher educational level (odds ratio (OR) = 4.42; 95%CI 1.70-11.47), in those who knew that HZ could cause postherpetic neuralgia (OR = 2.56; 95%CI 1.05-6.25) or major cardiovascular events (OR = 4.23; 95%CI 1.50-11.91), in those who had participated in professional updates on vaccinations (OR = 3.86; 95%CI 1.51-9.87) and in those who stated the need for further information about the RZV (OR = 6.43; 95%CI 1.42-29.98). Younger HPs (coefficient (β) = -0.02; 95%CI -0.04--0.01), those with a positive attitude toward RZV safety (β = 2.92; 95%CI 2.49-3.36) and those who had previously cared for patients with HZ (β = 0.45; 95%CI 0.03-0.88) reported a more positive attitude toward RZV effectiveness. The practice of recommending vaccination was more prevalent in younger HPs (OR = 0.94; 95%CI 0.89-0.99), in those who had a master's degree or higher education (OR = 7.21; 95%CI 1.44-36.08), in those with more positive attitudes toward RZV effectiveness (OR = 7.17; 95%CI 1.71-30.03) and in HPs who had already recommended the vaccine to patients in the past (OR = 4.03; 95%CI 1.08-14.96). Conclusions: Despite being a single-center study, our research brings attention to factors that currently impact cardiac HPs' approaches to RZV. The findings indicate potential measures to enhance HPs' awareness and practices, ultimately aiming to improve vaccination adherence and reduce the burden associated with HZ.

Smoking habits predict adverse effects following mRNA COVID-19 vaccine: Empirical evidence from a pilot study

Objectives

The aim of this research was to investigate the possible association between smoking habits and the incidence of adverse effects (AE) following mRNA COVID-19 vaccine.

Study design

A longitudinal observational study was conducted in a sample of Italian healthcare workers (HCW).

Methods

HCWs who were administered mRNA COVID-19 vaccine (either BNT162b2 or mRNA-1273) were evaluated for the occurrence of AEs after three vaccine doses. Multivariate Poisson regression analyses were fitted to predict AE risk according to smoking characteristics – such as number of tobacco cigarettes smoked per day, smoking time and use of electronic cigarette (e-cig).

Results

Out of 320 total participants, 72 (22.5%) smoked cigarettes and 50 (15.6%) used e-cig, 49 of which being dual users. Tobacco smoking significantly increased the risks of muscle and joint pain during the primary COVID-19 vaccination cycle, and of chills during the whole vaccination series. The number of cigarettes smoked per day and vaping variously predicted AE onset during the whole cycle, with a tendency to respectively reduce and increase their risks. Duration of smoking did not affect any AE, except for headache after booster dose. Most results remained significant after Bonferroni adjustment of significance level.

Conclusion

Our pilot study indicated a possible effect of smoking habits on AE onset. Our research offers evidence that helps understanding possible predictors of the interindividual variability in COVID-19 vaccine response, serving as a reference for further studies on the effect smoking on vaccine safety and effectiveness.

Risk of Repeated Adverse Effects following Booster Dose of mRNA COVID-19 Vaccine: Results from the MOSAICO Study

The successful deployment of safe and effective vaccines against coronavirus disease 2019 (COVID-19) has been crucial in reducing the global disease burden. Owing to the need for vaccination series over time, continuous observational studies are needed to estimate the COVID-19 vaccine response in real-world conditions. In particular, the detection, assessment, and understanding of adverse effects following immunization (AEFI) with a COVID-19 vaccine are crucial to better address vaccination strategies. Therefore, this study aimed to investigate the risk of repeated AEFI post-administration of a booster dose of mRNA COVID-19 vaccine in a sample of healthcare workers (HCWs) in an Italian teaching hospital. The data on any local and systemic AEFI were studied in multivariate Poisson regression analyses to model the association between the incidence of each postvaccination symptom and its prior reporting after the administration of the previous doses. Overall, compared with the primary vaccination series, the majority of post-third dose AEFI were less reported. The results from multivariable models showed that the likelihood of reporting an AEFI after the third dose was higher in those who experienced the same postvaccination symptom after the second dose (all AEFI except for itch at injection site) and, although not significant for all AEFI, after the first dose. Any associations with age, gender, smoking habits, previous SARS-CoV-2 infection and other characteristics, as well as the health impact of AEFI were also assessed. Taken together, the results from this research support reframe AEFI symptoms as signals of a robust postvaccination reaction as well as of common vaccine response, and they add important data to inform booster vaccination strategies in HCWs and, extensively, in the adult population.