Effectiveness of mRNA BNT162b2 COVID-19 vaccine against SARS-CoV-2 Delta variant among elderly residents from a long-term care facility, South of France, May 2021.

OBJECTIVE: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Delta variant was classified as a variant of concern in May 2021 due to its increased transmissibility. It became dominant in Europe during the summer, raising concerns on the effectiveness of vaccines. We assessed the vaccine effectiveness (VE) of mRNA BNT162b2 (BioNTech-Pfizer) against SARS-CoV-2 Delta variant during an outbreak affecting long-term care facility (LTCF) residents in southern France, May 2021. MATERIALS AND METHODS: We conducted a retrospective cohort study among LTCF residents. We described sex, age, dependency level, reverse transcription PCR and sequencing results, clinical evolution, vaccination status. We compared attack rates of SARS-CoV-2 infection, symptomatic coronavirus disease 2019 (COVID-19), and severe COVID-19 (respiratory support, hospitalization, and/or death) by vaccination status (two doses administered vs. none) to estimate VE (1 - Relative Risk [RR]) with 95% confidence intervals (CI). VE was adjusted by age (Poisson regression). RESULTS: Among 72 LTCF residents, 75.0% (n=54) were women, mean age was 88.7 (SD 8.1) years, 69% (n=49/71) were severely dependent. SARS-CoV-2 infections were identified in 39 residents (54.2%), 11 with symptomatic, and eight with severe COVID-19. All sequenced samples (n=19, 48.7%) had the same Delta variant genomic sequence. Age-adjusted BNT162b2 VE against SARS-CoV-2 Delta variant infection was 11.2% (95% CI: 0.0-61.1%), it was 88.4% (95% CI: 59.9-96.7%) against symptomatic, and 93.5% (95% CI: 67.2-98.7%) against severe COVID-19. CONCLUSIONS: We found a high BNT162b2 VE against symptomatic and severe COVID-19 caused by SARS-CoV-2 Delta variant among LTCF elderly residents, but not against Delta variant infection. This supports vaccination rollout and the implementation of control measures for close contacts among vaccinated LTCF elderly residents.

Large outbreak of urogenital schistosomiasis acquired in Southern Corsica, France: monitoring early signs of endemicization?

OBJECTIVES: Clustered cases of urogenital schistosomiasis were reported in April 2014 among French and German tourists linked to exposure in the Cavu River, Southern Corsica, France, between 2011 and 2013. We set up national surveillance for autochthonous urogenital schistosomiasis to document the largest possible number of cases in order to identify potential sites of transmission and to determine the extent of the outbreak in France and Corsica. METHODS: The early response consisted mostly of prohibiting swimming in the river, performing a nationwide serologic screening of all persons exposed to the river between 2011 and 2013 and treating confirmed cases. Physicians were asked to report all patients with one or more positive antischistosome serologic test. Cases were defined as occurring in a resident of France with serologic evidence of schistosomiasis or schistosome eggs in urine and no history of contact with freshwater in known endemic areas. We documented symptoms as well as place and time of exposure to freshwater for all subjects. To estimate the outbreak size, we modelled the effect of the 2014 nationwide screening on the 2011-2015 time series of serodiagnosed schistosomiasis cases using log-linear autoregression. RESULTS: In 2014, a total of 106 autochthonous cases were reported, including 35 symptomatic infections. All patients had swum in the Cavu during summer 2013. Over 30 000 persons were likely screened for autochthonous schistosomiasis. The model-estimated outbreak size was 338 cases, including 36 serodiagnosed in 2015. CONCLUSIONS: Besides the 2013 outbreak, there is evidence of small-scale transmission in 2015 in Corsica. Early detection and control of recurrences requires raising community and medical awareness.