Abstract
From January 18th to August 13th, 2021, 13,804 unvaccinated and 1,156 patients who had received at least one COVID-19 vaccine dose were tested qPCR-positive for SARS-CoV-2 in our center. Among vaccinated patients, 949, 205 and 2 had received a single, two or three vaccine doses, respectively. Most patients (80.3%) had received the Pfizer-BioNTech vaccine. The SARS-CoV-2 variants infecting vaccinated patients varied over time, reflecting those circulating in the Marseille area, with a predominance of the Marseille-4/20A.EU2 variant from weeks 3 to 6, of the Alpha/20I variant from weeks 7 to 25, and of the Delta/21A variant from week 26. SARS-CoV-2 infection was significantly more likely to occur in the first 13 days post-vaccine injection in those who received a single dose (48.9%) than two doses (27.4%, p< 10–3). Among 161 patients considered as fully vaccinated, i.e., >14 days after the completion of the vaccinal scheme (one dose for Johnson and Johnson and two doses for Pfizer/BioNTech, Moderna and Sputnik vaccines), 10 (6.2%) required hospitalization and four (2.5%) died. Risks of complications increased with age in a nonlinear pattern, with a first breakpoint at 54, 33, and 53 years for death, transfer to ICU, and hospitalization, respectively. Among patients infected by the Delta/21A or Alpha/20I variants, partial or complete vaccination exhibited a protective effect with a risk divided by 3.1 for mortality in patients ≥ 55 years, by 2.8 for ICU transfer in patients ≥ 34 years, and by 1.8 for hospitalization in patients ≥ 54 years. Compared to partial vaccination, complete vaccination provided an even stronger protective effect, confirming effectiveness to prevent severe forms of COVID-19.
Highlights
Since the beginning of 2020, COVID-19 infected more than 254 million people and caused more than 5.1 million deaths worldwide1
The study is a retrospective cohort study of all SARS-CoV-2positive patients diagnosed at Mediterranee Infection Institute from January 18th 2021, day of the first vaccine dose received by the first vaccinated patients who tested positive in our center, to August 13th 2021
Age being identified as a major prognostic factor in COVID (Lagier et al, 2020), to determine whether the increase in risk was linear with age, we used a ROC analysis for age on death, intensive care unit (ICU) admission and hospitalization
Summary
Since the beginning of 2020, COVID-19 infected more than 254 million people and caused more than 5.1 million deaths worldwide (accessed on November, 23, 2021). The first clinical trial of mRNA vaccine in lipid nanoparticles was performed in 2015 (influenza). Before COVID-19, large scale use of mRNA vaccine in lipid nanoparticles and their safety in large-scale utilization in the real world were lacking (Dolgin, 2021). Several COVID-19 vaccines have been developed worldwide, mostly based on two technologies (mRNA and adenoviral vector) and 7.5 billion doses were administered (Ritchie et al, 2020). The effectiveness of the Pfizer-BioNTech BNT162b2 and Moderna mRNA-1273 vaccines for preventing symptomatic infection was reported to be 60–80% > 14 days following a first dose and 90% with two doses (Amit et al, 2021; Hall et al, 2021a,b; Thompson et al, 2021a). Recent reports described increasing numbers of vaccine breakthrough infections (Bahl et al, 2021; Blanquart et al, 2021; GlatmanFreedman et al, 2021; Puranik et al, 2021; Scobie et al, 2021; Thompson et al, 2021b)
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