Epidemiology
· The incubation period during the pandemic of COVID-19: a systematic review and meta-analysis: Epidemiology experts from University of Sousse, Tunisia conducted a systematic review and meta-analysis of 42 studies to determine the incubation period of COVID-19. Mean and median incubation periods were 8 days and 12 days respectively, and pooled mean incubation period was determined to be 6.2 days (95% CI 5.4, 7.0) which may vary due to moderator variables such as population, severity, sex-ratio, study quality, and method of calculation. However, the 99th percentile of incubation time was 20.4 days, suggesting that a 14-day quarantine may not be sufficient to protect against the spread of COVID-19.

· Prevalence and Mortality due to COVID-19 in HIV Co-Infected Population: A Systematic Review and Meta-Analysis: A systematic review and meta-analysis conducted by researchers affiliated with Maoming People's Hospital and Southern Medical University in China included 14 studies and found a prevalence of 0.774% and mortality rate of 8.814% of COVID-19 infection among people living with HIV/acquired immunodeficiency syndrome (PLWHA), however there was no association of increased mortality among PLWHA with COVID-19 compared to non-PLWHA (RR 0.96, 95% CI, 0.88-1.06). Increased mortality was found in PLWHA with the presence of comorbidities including DM (RR 5.2, 95% CI, 4.25-6.36), HTN and chronic cardiac disease (RR 4.2, 95% CI 1.09-16.10), and CKD (RR 8.43, 95% CI 5.49-12.93). These findings suggest the need for follow-up studies to investigate HIV viral load, CD4 count, and antiretroviral therapy in relation to COVID-19 outcomes.
Transmission & Prevention
· Effectiveness of mRNA COVID-19 vaccines against SARS-CoV-2 infection in a cohort of healthcare personnel: A team of multidisciplinary researchers associated with Mayo Clinic and University of Minnesota conducted a retrospective study on 45,162 healthcare personnel (HCP) to analyze the effectiveness of Pfizer and Moderna mRNA SARS-CoV-2 vaccines. During the study period 1,125 HCP tested positive for SARS-CoV-2, and vaccine effectiveness was determined to be 78% for partial vaccination and 96% for complete vaccination after adjusting for age, gender, region, job, and week of vaccination. These results suggest the high effectiveness of the Pfizer and Moderna vaccines and the importance of bringing widespread immunity to SARS-CoV-2.
· SARS-CoV-2 Infection after Vaccination in Health Care Workers in California: In a letter to the editor, researchers associated with UCSD and UCLA health systems discuss SARS-CoV-2 infection rates in vaccinated healthcare workers in California. 36,659 healthcare workers received the first vaccine dose, 28,184 received the second dose, and 379 vaccinated healthcare workers tested positive at least 1 day after vaccination. Vaccinated healthcare workers at UCSD had a 1.19% absolute risk of testing positive for SARS-CoV-2, while those at UCLA had a 0.97% risk. These results suggest the high efficacy of the Pfizer and Moderna vaccines.
Management
· Pulmonary function and radiological features 4 months after COVID-19: first results from the national prospective observational Swiss COVID-19 lung study: A multicenter prospective observational cohort study conducted by researchers from multiple medical institutions in Switzerland enrolled 113 individuals diagnosed with COVID-19 between May 1 - September 15, 2020 and monitored respiratory outcomes 4 months later. Patients who had severe/critical COVID-19 had significantly lower TLC, FVC, FEV1, and DLCO compared to those with mild/moderate disease, and patients with severe/critical COVID-19 were more likely to have mosaic attenuation pattern with hypo-attenuated areas (66% versus 13%, p=0.007), reticulations (59% versus 13%, p=0.02), and architectural distortion (52% versus 13%, p=0.055). DLCO was the strongest independent factor associated with previous severe/critical disease, suggesting that systematic follow-up of pulmonary function is essential for patients who recover from severe and critical COVID-19 and DLCO is the single most important factor at 4-month follow-up.
R&D: Diagnosis & Treatments
· Clinical Outcomes Associated With Methylprednisolone in Mechanically Ventilated Patients With COVID-19: A case-control study conducted by pharmacy, infectious disease, and pulmonary specialists from Columbia University Irving Medical Center on 117 mechanically ventilated COVID-19 patients, where the experimental group (n = 48) received methylprednisone within 14 days of admission showed that the methylprednisone group had significantly higher ventilator-free days (p = 0.044) and probability of extubation by day 28 (p = 0.087) compared to the control group. Overall, these results indicate the effectiveness of corticosteroid treatment in severe COVID-19 patients requiring mechanical ventilation.
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