Background Although the three vaccines against coronavirus disease 2019 (Covid-19) that have received emergency use authorization in the United States are highly effective, breakthrough infections are occurring. Data are needed on the serial use of homologous boosters (same as the primary vaccine) and heterologous boosters (different from the primary vaccine) in fully vaccinated recipients. Methods In this phase 1–2, open-label clinical trial conducted at 10 sites in the United States, adults who had completed a Covid-19 vaccine regimen at least 12 weeks earlier and had no reported history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection received a booster injection with one of three vaccines: mRNA-1273 (Moderna) at a dose of 100 μg, Ad26.COV2.S (Johnson & Johnson–Janssen) at a dose of 5×10 10 virus particles, or BNT162b2 (Pfizer–BioNTech) at a dose of 30 μg. The primary end points were safety, reactogenicity, and humoral immunogenicity on trial days 15 and 29. Results Of the 458 participants who were enrolled in the trial, 154 received mRNA-1273, 150 received Ad26.COV2.S, and 153 received BNT162b2 as booster vaccines; 1 participant did not receive the assigned vaccine. Reactogenicity was similar to that reported for the primary series. More than half the recipients reported having injection-site pain, malaise, headache, or myalgia. For all combinations, antibody neutralizing titers against a SARS-CoV-2 D614G pseudovirus increased by a factor of 4 to 73, and binding titers increased by a factor of 5 to 55. Homologous boosters increased neutralizing antibody titers by a factor of 4 to 20, whereas heterologous boosters increased titers by a factor of 6 to 73. Spike-specific T-cell responses increased in all but the homologous Ad26.COV2.S-boosted subgroup. CD8+ T-cell levels were more durable in the Ad26.COV2.S-primed recipients, and heterologous boosting with the Ad26.COV2.S vaccine substantially increased spike-specific CD8+ T cells in the mRNA vaccine recipients. Conclusions Homologous and heterologous booster vaccines had an acceptable safety profile and were immunogenic in adults who had completed a primary Covid-19 vaccine regimen at least 12 weeks earlier. (Funded by the National Institute of Allergy and Infectious Diseases; DMID 21-0012 ClinicalTrials.gov number, NCT04889209 .)

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Background: Literature suggests that antibiotic prescribing in COVID-19 patients is high. Currently, there are insufficient data on what drives antibiotic prescribing practices throughout the COVID-19 pandemic. Objective: This study sought to determine antibiotic use rates and identify risk factors for antibiotic prescribing in hospitalized patients. It was the first study to assess risk factors for receiving more than 1 course of antibiotics. Methods: This was a retrospective, multi-center, observational study. Patients admitted from March 1, 2020, to May 31, 2020, and treated for COVID-19 were included. The primary endpoint was the rate of antibiotic use during hospitalization. Secondary endpoints included risk factors associated with antibiotic use, risk factors associated with receiving more than 1 antibiotic course, and rate of microbiologically confirmed infections. Results: A total of 208 encounters (198 patients) were included in the final analysis. Eighty-three percent of patients received at least 1 course of antibiotics, despite low rates of microbiologically confirmed infection (12%). Almost one-third of patients (30%) received more than 1 course of antibiotics. Risk factors identified for both antibiotic prescribing and receiving more than 1 course of antibiotics included increased hospital length of stay (median 12 days), intensive care unit admission, and the necessity for mechanical ventilation. Conclusion and Relevance: There were high rates of antibiotic prescribing with low rates of microbiologically confirmed bacterial co-infection. Many patients received more than 1 course of antibiotics during hospitalization. This study highlights the importance and demand for appropriate antibiotic stewardship practices in COVID-19 patients.

Literature suggests that antibiotic prescribing in COVID-19 patients is high, despite low rates of confirmed bacterial infection. There are little data on what drives prescribing habits. This retrospective, multi-center, observational study sought to determine antibiotic prescribing rates and risk factors for antibiotic prescribing in hospitalized patients. Patients admitted from March 1, 2020 to May 31, 2020 and treated for PCR-confirmed COVID-19 were included. The primary endpoint was the rate of antibiotic use during hospitalization. Secondary endpoints included risk factors associated with antibiotic use, risk factors associated with receiving more than one antibiotic course, and rate of microbiologically confirmed infections. A total of 208 encounters (198 patients) were included in the final analysis. Eighty-three percent of patients received at least one course of antibiotics, despite low rates of microbiologically confirmed infection (12%). Almost one-third of patients (30%) received more than one course of antibiotics. There was a low rate of respiratory cultures obtained (32%). Risk factors identified in a univariate analysis for both antibiotic prescribing and receiving more than one course of antibiotics were more serious illness, increased hospital length of stay, ICU admission, mechanical ventilation, and ARDS. This study highlights the need for increased antibiotic stewardship practices in COVID-19 patients. Further studies should be conducted to determine the utility of different stewardship initiatives in COVID-19 patients.