Surveillance, contact tracing and characteristics of SARS-CoV-2 transmission in educational settings in Northern Italy, September 2020 to April 2021
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Abstract
The role of school contacts in the spread of the virus and the effectiveness of school closures in controlling the epidemic is still debated. We aimed to quantify the risk of transmission of SARS-CoV-2 in the school setting by type of school, characteristics of the index case and calendar period in the Province of Reggio Emilia (RE), Italy. The secondary aim was to estimate the speed of implementation of contact tracing.
Methods
A population-based analysis of surveillance data on all COVID-19 cases occurring in RE, Italy, from 1 September 2020, to 4 April 2021, for which a school contact and/or exposure was suspected. An indicator of the delay in contact tracing was calculated as the time elapsed since the index case was determined to be positive and the date on which the swab test for classmates was scheduled (or most were scheduled).
Results
Overall, 30,184 and 13,608 contacts among classmates and teachers/staff, respectively, were identified and were recommended for testing, and 43,214 (98.7%) underwent the test. Secondary transmission occurred in about 40% of the investigated classes, and the overall secondary case attack rate was 4%. This rate was slightly higher when the index case was a teacher but with almost no differences by type of school, and was stable during the study period. Speed of implementation of contact tracing increased during the study period, with the time from index case identification to testing of contacts being reduced from seven to three days. The ability to identify the possible source of infection in the index case also increased.
Conclusions
Despite the spread of the Alpha variant during the study period in RE, the secondary case attack rate remained stable from school reopening in September 2020 until the beginning of April 2021.
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SciScore for 10.1101/2021.09.03.21263061: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: Ethical statement: The study was approved by the Area Vasta Emilia Nord Ethics Committee (no. 2020/0045199).
Consent: The Ethics Committee authorised the use of subject data even in the absence of consent if every reasonable effort had been made to contact that subject no one denied consent.Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources Data were analysed using Microsoft Excel and Stata v. Microsoft Excelsuggested: (Microsoft Excel, RRID:SCR_016137)13.1 (Statacorp, Tx). Statacorpsuggested: NoneResults from OddPub: We did not detect open data. We also did not …
SciScore for 10.1101/2021.09.03.21263061: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: Ethical statement: The study was approved by the Area Vasta Emilia Nord Ethics Committee (no. 2020/0045199).
Consent: The Ethics Committee authorised the use of subject data even in the absence of consent if every reasonable effort had been made to contact that subject no one denied consent.Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources Data were analysed using Microsoft Excel and Stata v. Microsoft Excelsuggested: (Microsoft Excel, RRID:SCR_016137)13.1 (Statacorp, Tx). Statacorpsuggested: NoneResults from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Limitations and strengths: The main limitation of this study is that any observed association between changes in secondary attack rate and school or index case characteristics and especially actions implemented during the study period could be confounded by other factors that we could not measure. Among these, the most important was the spread of the Alpha variant, which probably started in our region around Christmas and which became the dominant circulating variant in February. Unfortunately, as very few cases were sequenced in Italy in that period,15 we cannot determine which clusters were due to the Alpha variant. Other variables that were missing or difficult to standardize were the duration and intensity of contacts between the index case and other classmates and the control measures each school independently put in place both before the occurrence of the case and during the outbreak. The main strength of the study is its population-based nature; it included all cases for a which a school contact or exposure was identified. For an analysis of routine surveillance data, the completeness of field investigations is surprisingly high; only a few classes were not characterized, and very few classmates refused to be tested. Each outbreak in each school was investigated and re-checked for plausibility by the investigation team, thereby partially overcoming the shortcomings of cross-sectional, retrospective and self-reported studies.
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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