Despite the impact of the COVID-19 vaccination, vaccine hesitancy is a matter of concern. Despite a lower disease incidence, people continue to start primo-vaccination late. The aim of this study is to characterize people late primo-vaccinated and the reasons that led them to start vaccination. A quantitative, descriptive and prospective study was performed on the basis of phone surveys of people vaccinated from February to May 2022 in the Region of Murcia (Spain). The survey included socio-demographic and COVID-19 information, self-perception risk, vaccine security, Fear of COVID-19 Scale, reasons for not being vaccinated and reasons that have led them to vaccination. From a total of 1768 people receiving primo-vaccination, 798 people were contacted, and 338 people completed the survey. Among the interviewed people, 57% reported non-health-related reasons to get vaccinated, travel reasons being the primary one. The most reported health-related reason was a fear of COVID-19. There was a significant positive association between vaccination for health-related reasons and female gender (β = 0.72), cohabiting with a vulnerable person (β = 0.97), higher self-perceived risk (β = 0.13) and vaccine security dimension (β = 0.14). We identified two different profiles of people with late COVID-19 primo-vaccination, with health-related or non-health-related reasons. This work can be useful in designing specific communication strategies.

The hexavalent vaccines DT3aP-HBV-IPV/Hib and DT2aP-HBV-IPV-Hib are routinely used for primary immunization of infants against diphtheria, tetanus, pertussis, hepatitis B virus, poliomyelitis, and Haemophilus influenzae type b. A recent publication showed that after primary immunization with these vaccines, the odds ratios of adverse reactions (ARs) were significantly lower for DT3aP-HBV-IPV/Hib than for DT2aP-HBV-IPV-Hib. Our aim is to understand the impact of the various reactogenicity profiles at country level by comparing the ARs induced by one dose of DT3aP-HBV-IPV/Hib versus DT2aP-HBV-IPV-Hib in the primary infant immunization course. A mathematical projection tool was developed to simulate vaccination of infants with both vaccines in six countries: Austria, the Czech Republic, France, Jordan, Spain, and the Netherlands. Proportions of three local and five systemic ARs of interest for both vaccines were based on findings from a previous meta-analysis of ARs in infants. The absolute risk reductions calculated ranged from 3.0% (95% confidence interval [CI]: 2.8%–3.2%) for “Swelling at the injection site, any grade” to 10.0% (95% CI: 9.5%–10.5%) for “Fever, any grade.” The difference in occurrence of the AR “Fever, any grade” between vaccines in 2020 ranged from over 7,000 in Austria to over 62,000 in France. Over 5 years, this would amount to a reduction of over 150,000 ARs in Austria and over 1.4 million ARs in France when using DT3aP-HBV-IPV/Hib instead of DT2aP-HBV-IPV-Hib. In conclusion, the estimated numbers of ARs following hexavalent vaccination in six countries showed that vaccination of infants with DT3aP-HBV-IPV/Hib could lead to fewer ARs than vaccination with DT2aP-HBV-IPV-Hib.