Eurosurveillance - Volume 30, Issue 16, 24 April 2025

Vaccine-derived polioviruses (VDPVs) continue to circulate internationally, causing sporadic cases and outbreaks of paralytic polio in countries certified as polio-free. In 2022, sustained detection of type 2 VDPVs was reported in environmental surveillance samples collected from London. Genetic mutations indicative of loss of attenuation of virulence were observed, consistent with community transmission events over several months.

We aimed to determine the extent of geographical spread of transmission in an area of environmental poliovirus detection.

We implemented an opportunistic, cross-sectional survey in areas where environmental surveillance indicated sustained VDPV transmission between October 2022 and April 2023. Residual stool samples taken from children < 16 years presenting to primary or secondary healthcare were examined for enteroviruses, including poliovirus. Methods for poliovirus detection recommended by the World Health Organization, including virus isolation in cell culture, PCR and molecular characterisation, were applied to residual stool material on a daily basis with real-time clinical reporting.

We examined 1,251 stool samples from 1,051 children presenting to healthcare with illness over a 6-month period. A range of enteroviruses from groups A, B and C were found, but no poliovirus was detected. Documented polio vaccination coverage was high, between 95% and 98% in under 5-year-olds.

Poliovirus was not widespread in the area of environmental poliovirus isolation. Opportunistic poliovirus testing of residual stool samples taken from children seeking healthcare was feasible and can be implemented rapidly in areas where poliovirus circulation is suspected, although untargeted sampling may not adequately capture populations at highest risk.

Vaccination programmes initiated in the early 1970s reduced the incidence of measles in Austria, which resulted in the interruption of endemic measles virus (MeV) circulation and the achievement of elimination status in 2018. However, large outbreaks occurred in 2023 and 2024.

By assessing MeV-specific IgG antibody levels, we analysed if immunity recently declined due to the COVID-19 pandemic, vaccine-induced immunity waned over long term or immunity gaps already pre-existed in the population.

We determined anti-MeV antibody levels in a retrospective dataset of 56,360 diagnostic samples (from 50,754 individuals) collected 2010–2024 and correlated antibody cutoffs to titres from a live-virus neutralisation test.

Individuals born before 1970 (n = 15,007) had antibody levels > 3,000 IU/L, persisting into higher age, and < 2% (n = 300) of them were seronegative. In contrast, individuals born after 1990 (n = 12,778) displayed seronegativity rates of 13–20% and lower median antibody concentrations in seropositive individuals (449–773 IU/L). In these individuals, antibody levels decreased noticeably between the ages of 2 and 10 years but remained stable between those aged 10 and 30 years. There was no significant difference in seronegativity rates at the age of 12–24 months in children born 2016–2019 and 2020–2022 (the years of the COVID-19 pandemic).

In Austria, there are significant immunity gaps in individuals born after 1970, which pre-existed before the COVID-19 pandemic. Thus, young and middle-aged populations not immune against measles should be vaccinated to counteract a further decline of immunity at the population level and prevent outbreaks whenever MeV is imported.

Since the late 2000s, several major measles epidemics have occurred in Europe, including France. In 2017, the French Health Ministry extended from three to 11 the number of mandatory childhood vaccines required for preschool and primary school admission; these included the vaccine against measles, mumps and rubella (MMR).

Our aim was to assess if this measure helped to improve MMR vaccine timeliness (VT) or reduce socioeconomic inequalities in MMR vaccine coverage.

A nationwide study of three birth cohorts (2015, 2017, 2019) followed up 2.1 million children for 48 months to assess the course of the timeliness of MMR vaccine dispensation, before and after it became mandatory in France (January 2018). Data came from the French national health insurance fund drug reimbursement database.

Despite improvements from 2015 to 2019, pharmacies dispensed MMR vaccines late for 33% of children in the 2019 cohort (mean cumulative delay compared with recommended dates: 7.1 months). Vaccines for children from low-income families were dispensed later (mean delay of at least +1 month) than those from higher-income families. The 2019 cohort did not reach the 95% WHO target of two MMR doses at 24 months of age, nor at 48 months.

With measles intensifying worldwide, these vaccination delays and inequalities may contribute to the resurgence of epidemics. In addition to vaccination mandates, an ambitious public health policy is needed to reduce inequalities in access to vaccination and to improve parents’ vaccine acceptance through educational strategies.