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1.
Clin Infect Dis ; 2021 Aug 19.
Article in English | MEDLINE | ID: covidwho-1708892

ABSTRACT

BACKGROUND: Post-vaccination infections challenge the control of the COVID-19 pandemic. METHODS: We matched 119 cases of post-vaccination SARS-CoV-2 infection with BNT162b2 mRNA, or ChAdOx1 nCOV-19, to 476 unvaccinated patients with COVID-19 (Sept 2020-March 2021), according to age and sex. Differences in 60-day all-cause mortality, hospital admission, and hospital length of stay were evaluated. Phylogenetic, single nucleotide polymorphism (SNP) and minority variant allele (MVA) full genome sequencing analysis was performed. RESULTS: 116/119 cases developed COVID-19 post first vaccination dose (median 14 days, IQR 9 - 24 days). Overall, 13/119 (10∙9%) cases and 158/476 (33∙2%) controls died (p<0.001), corresponding to 4∙5 number needed to treat (NNT). Multivariably, vaccination was associated with 69∙3% (95%CI 45∙8 - 82∙6) relative risk (RR) reduction in mortality. Similar results were seen in subgroup analysis for patients with infection onset ≥14 days after first vaccination (RR reduction 65∙1%, 95%CI 27∙2 - 83∙2, NNT 4∙5), and across vaccine subgroups (BNT162b2: RR reduction 66%, 95%CI 34∙9 - 82∙2, NNT 4∙7, ChAdOx1: RR reduction 78∙4%, 95%CI 30∙4 - 93∙3, NNT 4∙1). Hospital admissions (OR 0∙80, 95%CI 0∙51 - 1∙28), and length of stay (-1∙89 days, 95%CI -4∙57 - 0∙78) were lower for cases, while Ct values were higher (30∙8 versus 28∙8, p = 0.053). B.1.1.7 was the predominant lineage in cases (100/108, 92.6%) and controls (341/446, 76.5%). Genomic analysis identified one post-vaccination case harboring the E484K vaccine escape mutation (B.1.525 lineage). CONCLUSIONS: Previous vaccination reduces mortality when B.1.1.7 is the predominant lineage. No significant lineage-specific genomic changes during phylogenetic, SNP and MVA analysis were detected.

2.
Infect Control Hosp Epidemiol ; : 1-7, 2021 Nov 22.
Article in English | MEDLINE | ID: covidwho-1569173

ABSTRACT

OBJECTIVE: To understand the transmission dynamics of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) in a hospital outbreak to inform infection control actions. DESIGN: Retrospective cohort study. SETTING: General medical and elderly inpatient wards in a hospital in England. METHODS: Coronavirus disease 2019 (COVID-19) patients were classified as community or healthcare associated by time from admission to onset or positivity using European Centre for Disease Prevention and Control definitions. COVID-19 symptoms were classified as asymptomatic, nonrespiratory, or respiratory. Infectiousness was calculated from 2 days prior to 14 days after symptom onset or positive test. Cases were defined as healthcare-associated COVID-19 when infection was acquired from the wards under investigation. COVID-19 exposures were calculated based on symptoms and bed proximity to an infectious patient. Risk ratios and adjusted odds ratios (aORs) were calculated from univariable and multivariable logistic regression. RESULTS: Of 153 patients, 65 were COVID-19 patients and 45 of these were healthcare-associated cases. Exposure to a COVID-19 patient with respiratory symptoms was associated with healthcare-associated infection irrespective of proximity (aOR, 3.81; 95% CI, 1.6.3-8.87). Nonrespiratory exposure was only significant within 2.5 m (aOR, 5.21; 95% CI, 1.15-23.48). A small increase in risk ratio was observed for exposure to a respiratory patient for >1 day compared to 1 day from 2.04 (95% CI, 0.99-4.22) to 2.36 (95% CI, 1.44-3.88). CONCLUSIONS: Respiratory exposure anywhere within a 4-bed bay was a risk, whereas nonrespiratory exposure required bed distance ≤2.5 m. Standard infection control measures required beds to be >2 m apart. Our findings suggest that this may be insufficient to stop SARS-CoV-2 transmission. We recommend improving cohorting and further studies into bed distance and transmission factors.

3.
Clin Infect Dis ; 2021 Aug 19.
Article in English | MEDLINE | ID: covidwho-1364783

ABSTRACT

BACKGROUND: Post-vaccination infections challenge the control of the COVID-19 pandemic. METHODS: We matched 119 cases of post-vaccination SARS-CoV-2 infection with BNT162b2 mRNA, or ChAdOx1 nCOV-19, to 476 unvaccinated patients with COVID-19 (Sept 2020-March 2021), according to age and sex. Differences in 60-day all-cause mortality, hospital admission, and hospital length of stay were evaluated. Phylogenetic, single nucleotide polymorphism (SNP) and minority variant allele (MVA) full genome sequencing analysis was performed. RESULTS: 116/119 cases developed COVID-19 post first vaccination dose (median 14 days, IQR 9 - 24 days). Overall, 13/119 (10∙9%) cases and 158/476 (33∙2%) controls died (p<0.001), corresponding to 4∙5 number needed to treat (NNT). Multivariably, vaccination was associated with 69∙3% (95%CI 45∙8 - 82∙6) relative risk (RR) reduction in mortality. Similar results were seen in subgroup analysis for patients with infection onset ≥14 days after first vaccination (RR reduction 65∙1%, 95%CI 27∙2 - 83∙2, NNT 4∙5), and across vaccine subgroups (BNT162b2: RR reduction 66%, 95%CI 34∙9 - 82∙2, NNT 4∙7, ChAdOx1: RR reduction 78∙4%, 95%CI 30∙4 - 93∙3, NNT 4∙1). Hospital admissions (OR 0∙80, 95%CI 0∙51 - 1∙28), and length of stay (-1∙89 days, 95%CI -4∙57 - 0∙78) were lower for cases, while Ct values were higher (30∙8 versus 28∙8, p = 0.053). B.1.1.7 was the predominant lineage in cases (100/108, 92.6%) and controls (341/446, 76.5%). Genomic analysis identified one post-vaccination case harboring the E484K vaccine escape mutation (B.1.525 lineage). CONCLUSIONS: Previous vaccination reduces mortality when B.1.1.7 is the predominant lineage. No significant lineage-specific genomic changes during phylogenetic, SNP and MVA analysis were detected.

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