Assessment of varicella underreporting in Italy

Abstract

We conducted a study to assess the degree of varicella underreporting in Italy, and its distribution by age group and geographical area. Underreporting in individuals from 6 months to 20 years of age was computed as the ratio between the varicella seroprevalence in 1996 and the 1996 lifetime cumulative incidence based on statutory notifications. The degree of underreporting at the national level was 7.7 (95% CI 7.4-7.9); underreporting was greater in older age groups and in southern Italy. Quantification of underreporting can contribute to better understanding of the burden of varicella and to evaluating the potential impact of mass vaccination.

Burden of varicella in Italy, 2001–2010: analysis of data from multiple sources and assessment of universal vaccination impact in three pilot regions

“…As highlighted by two previous studies (Ciofi degli Atti et al, 2002;Gabutti et al, 2008), the passive surveillance system is affected by several limitations, such as under-notification, under-diagnosis and notification delays. Consequently, to correctly estimate the burden of the disease, data provided by the national statutory notification system need to be integrated with data from other sources, such as sero-epidemiological studies and active surveillance systems.…”

“…Analysis of varicella data reported to the Paediatric Sentinel Surveillance System of Vaccine-Preventable Diseases showed that the annual incidence rate was four-to sixfold higher than the incidence rate estimated by the statutory notifications. Considering data provided by both surveillance systems, it can be estimated that in Italy *500 000 cases of varicella occurred each year, which corresponds to the birth cohort (Ciofi degli Atti et al, 2002).…”

Current immunization policies for pneumococcal, meningococcal C, varicella and rotavirus vaccinations in Italy

“…Firstly, failure to report is common in Italy and varies in time and by geographical area. The degree of underreporting is markedly higher in southern Italy, compared to the rest of the country [9,10], producing false trends. Secondly, surveillance of pneumococcal and meningococcal diseases has been recently enhanced and the case definition of pneumococcal disease has been enlarged in 2007 to include notification of sepsis.…”

Varicella vaccination in Europe: are we ready for a universal childhood programme?

“…Italy also has a sentinel surveillance system based on paediatricians. However, regional differences in reporting have been seen in some areas [17]. In 2005, a sentinel surveillance scheme for both varicella and herpes zoster was established in Germany [24,53].…”