ABSTRACT
Herein, we describe the characteristics of vaccine breakthrough infections (VBI) in fully vaccinated individuals according to five vaccine strategies during the Delta wave in France. Inclusion criterion was a positive test at least 2 weeks after a full vaccine schedule: homologous vaccination with Pfizer-BioNTech (BNT162b2) or Moderna (mRNA-1273); heterologous vaccination with Astrazeneca and Pfizer-BioNTech (ChadOx1/BNT162b2); single-dose vaccines Johnson & Johnson (Ad26.COV2.S) or Astrazeneca (ChadOx1). A total of 1630 VBI from patients fully vaccinated between February and July were included in this study. SARS-CoV-2 sequencing performed for 1366 samples showed that the delta variant represented 94.1% (1286/1366). Delta-VBI were mainly symptomatic (mild symptoms) with no difference according to the vaccine strategy (p=0.362). The median RT-PCR Ct values at diagnosis were significantly different between symptomatic and asymptomatic cases only for BNT162b2 group (17.7 (15.07, 20.51) vs 19.00 (16.00, 23.00), p=0.004). Up to 50% of VBI was classified as early-VBI (infected less than one month after full immunization) for BNT162b2, mRNA-1273, ChadOx1, and J Ad26.COV2.S. People aged 14-49 yo were overrepresented in early VBI compared to non-early VBI for BNT162b2 and mRNA-1273 (73.92% vs 37.87% for BNT162b2 and 77.78% vs 46.67 % for mRNA-1273, p<0.05). Our data emphasize a high prevalence of Delta-VBI occurring only one month after full immunization in young patients that might be related to relaxation of barrier gestures.
Subject(s)
Breakthrough Pain , Protein S DeficiencyABSTRACT
Background: A comprehensive assessment of COVID-19 in healthcare workers (HCWs) including the investigation of viral shedding duration is critical.Methods: A longitudinal study including 319 HCWs was conducted. After SARS-CoV-2 screening with RT-PCR assay, other respiratory pathogens were tested with a multiplex molecular panel. For SARS-CoV-2 positive HCWs, the normalized viral load was determined weekly; viral culture and virus neutralization assay were also performed. For 190 HCWs tested negative for SARS-CoV-2, serological testing was performed one month after the inclusion.Findings: Of the 319 HCWs included, 67 (21.0%) were tested positive for SARS-CoV-2; two of them developed severe COVID-19. The proportion of smell and taste dysfunction was significantly higher in SARS-CoV-2 positive HCWs than in negative ones (38.8% vs 9.5% and 37.3% vs 10.7%, respectively, p<0.001). Of 67 positive patients, 9.1% were tested positive for at least another respiratory pathogen ( vs 19.5%, p=0.07). The proportion of HCWs with a viral load > 5.0 log 10 cp/ml (Ct value <25) was less than 15% at 8 days after symptom onset; 12% of them were still positive after 40 days (Ct >37). More than 90% of samples with cultivable virus had a viral load > 4.5 log 10 cp/ml (Ct < 26) and were collected within 10 days after symptom onset. From HCWs tested negative, 6/190 (3.2%) exhibited seroconversion for SARS-CoV-2 IgG antibodies.Interpretation: Our data suggest that the monitoring of normalized viral load (or its estimation through Ct values) can be useful for discontinuing isolation of HCWs and facilitating their safe return to work. HCWs presenting mild COVID-19 are unlikely infectious 10 days after symptom onset.Trial Registration: The clinical study registered on ClinicalTrial.gov (NCT04341142) has been fully detailed.Funding: Fondation des Hospices Civils de Lyon. bioMérieux provided diagnostic kits.Declaration of Interests: Several authors (KBP, FAF, GO, VC) are bioMérieux employees. AB has received a grant from bioMérieux and has served as consultant for bioMérieux. KBP, FAF, GO VC and AB were involved in data analysis, interpretation and wrote the article.Ethics Approval Statement: Written informed consent was obtained from all participants and approval was obtained from the national review board for biomedical research in April 2020 (Comité de Protection des Personnes Sud Méditerranée I, Marseille, France; ID RCB 2020-A00932-37).