Background On 7 February 2020, French Health authorities were informed of a confirmed case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in an Englishman infected in Singapore who had recently stayed in a chalet in the French Alps. We conducted an investigation to identify secondary cases and interrupt transmission. Methods We defined as a confirmed case a person linked to the chalet with a positive reverse-transcription polymerase chain reaction sample for SARS-CoV-2. Results The index case stayed 4 days in the chalet with 10 English tourists and a family of 5 French residents; SARS-CoV-2 was detected in 5 individuals in France, 6 in England (including the index case), and 1 in Spain (overall attack rate in the chalet: 75%). One pediatric case, with picornavirus and influenza A coinfection, visited 3 different schools while symptomatic. One case was asymptomatic, with similar viral load as that of a symptomatic case. Seven days after the first cases were diagnosed, 1 tertiary case was detected in a symptomatic patient with from the chalet a positive endotracheal aspirate; all previous and concurrent nasopharyngeal specimens were negative. Additionally, 172 contacts were monitored; all contacts tested for SARS-CoV-2 (N = 73) were negative. Conclusions The occurrence in this cluster of 1 asymptomatic case with similar viral load as a symptomatic patient suggests transmission potential of asymptomatic individuals. The fact that an infected child did not transmit the disease despite close interactions within schools suggests potential different transmission dynamics in children. Finally, the dissociation between upper and lower respiratory tract results underscores the need for close monitoring of the clinical evolution of suspected cases of coronavirus disease 2019.

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In France, measures including curfew and lockdown were implemented to control the COVID-19 pandemic second wave in 2020. This study descriptively assesses their possible effects, also relative to their timing. A considerable decrease in incidence of COVID-19 cases and hospital admissions was observed 7 to 10 days after mitigation measures were put in place, occurring earlier in metropolitan areas which had implemented these first. This temporal coincidence suggests the measures’ positive impact, consistent with international experiences.

In February and March 2016, four cases of serogroup B invasive meningococcal disease (IMD) occurred over 3 weeks in a small area north of Lyon in the Auvergne-Rhône-Alpes region, France. There were no deaths but two cases had sequelae. This community outbreak was caused by a rare meningococcal strain of the clonal complex ST-32, covered by the 4CMenB/Bexsero vaccine. The incidence rate for serogroup B IMD in this area was 22.5 per 100,000 inhabitants, which is above the epidemic threshold (10/100,000). The number of cases observed was significantly higher than expected in the age group of 0–24 year-olds (standardised incidence ratio: 96). These results suggested the potential emergence of this invasive strain in this sub-population. In accordance with French recommendations, it was decided to vaccinate the population aged between 2 months and 24 years, living, working or studying in the epidemic area. The vaccination campaign took place from April to September 2016. Vaccination coverage was estimated at 47% for one dose and 40% for two doses. The lowest coverage estimations were observed for the age groups younger than 3 and 15–19 years. Enhanced epidemiological and microbiological surveillance reported a fifth case in June 2016, outside the epidemic area.