SARS-CoV-2 transmission patterns in educational settings during the Alpha wave in Reggio-Emilia, Italy.

Different monitoring and control policies have been implemented in schools to minimize the spread of SARS-CoV-2. Transmission in schools has been hard to quantify due to the large proportion of asymptomatic carriers in young individuals. We applied a Bayesian approach to reconstruct the transmission chains between 284 SARS-CoV-2 infections ascertained during 87 school outbreak investigations conducted between March and April 2021 in Italy. Under the policy of reactive quarantines, we found that 42.5% (95%CrI: 29.5-54.3%) of infections among school attendees were caused by school contacts. The mean number of secondary cases infected at school by a positive individual during in-person education was estimated to be 0.33 (95%CrI: 0.23-0.43), with marked heterogeneity across individuals. Specifically, we estimated that only 26.0% (95%CrI: 17.6-34.1%) of students and school personnel who tested positive during in-person education caused at least one secondary infection at school. Positive individuals who attended school for at least 6 days before being isolated or quarantined infected on average 0.49 (95%CrI: 0.14-0.83) secondary cases. Our findings provide quantitative insights on the contribution of school transmission to the spread of SARS-CoV-2 in young individuals. Identifying positive cases within 5 days after exposure to their infector could reduce onward transmission at school by at least 30%.

[«Bridge Coding¼ ICD-9, ICD-10 and effects on mortality statistics]. / Il passaggio da ICD-9 a ICD-10 per le statistiche di mortalità.

OBJECTIVE: This study evaluates the impact of the introduction of ICD-10 on mortality statistics in Italy. DESIGN: «Bridge-Coding¼ analysis carried out by a working group that has coded a number of death certificates using both ICD-9 and ICD-10 versions. In 2006, a training project was launched in order to allow the group to standardize the coding procedures. SETTING: The study was carried out by professionals from the following regions: Emilia-Romagna, Veneto, Tuscany, Liguria; and from the towns of Biella and Milan. The analysis included 74,525 Death Certificates produced in the aforementioned areas. RESULTS: A limited variability was observed for the most important groups of diseases (diseases of the circulatory system and neoplasms), with low impact on mortality statistics. The variability was higher for "minor" diseases like infectious and respiratory diseases, and dementia. The variability was similar but not identical to that observed in other national and international studies. The «Bridge-Coding¼ analysis has a local impact. Furthermore, changes depending on the variation in the selection rules are impossible to predict or to correct with the trans-coding procedure. CONCLUSIONS: In some cases, the changes determined by the implementation of ICD-10 are not completely corrected by the transcoding procedure, even applying appropriate Comparability Ratios (CR) from «Bridge Coding¼ analysis like this. Studies on respiratory diseases, or dementia and some neoplasms require new coding procedures in only one ICD version. Quality and accuracy of the compilation of death certificates have more effect than a correct coding, though more casual and less evaluable by means of comparability studies like this one.