Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: Jan 7, 2021
Date Accepted: Apr 16, 2021
Date Submitted to PubMed: Apr 20, 2021
Analysis of the sources of COVID-19 transmission in France by Self-assessment Web-application before and after the partial autumnal lockdown: Observational Study
ABSTRACT
Background:
We developed a questionnaire on a web-application for COVID-19 circumstances of contamination analysis in France during the 2nd wave of pandemic.
Objective:
To analyze the impact on contaminations characteristics of the second partial lockdown in France to adapt health public restrictions to further pandemic surges.
Methods:
Between 12/15/2020 and 12/24/2020, after a national media campaign, users of sourcecovid.fr web-application were asked questions about their own or a close relative COVID-19 contamination after 8/15/2020 in France. Data of contamination’s circumstances were assessed and compared before and after the second partial lockdown which occurred on 10/25/2020 during the second wave of pandemic and was ongoing on 12/24/2020.
Results:
As of December 24, 2020, 441 000 connections on web-application were observed. 2218 questionnaires were assessable for analysis. 61.8% were sure of their contamination origin and 38.2% thought they knew it. The median age of users was 43.0 years (IQR 32 to 56), 50.7% were male. The median incubation time of the assessed cohort was 4.0 days (IQR 3 to 5). Private area (family and friends) was the main source of contamination (50.2%) followed by work colleagues: 27.7%. The main time of contamination of the day was the evening (35.3%) before the lockdown and was reduced to 18.2% after it (P<0.001). The person who transmitted the virus to the user before and after the lockdown was significantly different (P<0.001): a friend (29.0% vs 14.1%), a family close relative (23.1% vs 32.7%), a work colleague (23.9% vs 34.2%). The main location where the virus was transmitted to the users before and after lockdown was significantly different too (P<0.001), respectively: Home (21.3% vs 25.5%), at work (22.4% vs 29.6%), collective places (33.0% vs 15.0%), and care centers (4.4% vs 9.7%).
Conclusions:
Modalities of transmissions significantly changed before and after the 2nd lockdown in France. The main sources of contaminations remained the private area and work colleagues. Work became the main location of contamination after lockdown whereas collective places contaminations were strongly reduced. Clinical Trial: ClinicalTrials.gov NCT04670003
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