COVID-19 severity appears to be reduced in spring/summer.

BACKGROUND: because of different human behaviours, SARS-CoV-2 spread may be lower in spring/summer. On the contrary, it is not clearly known whether the clinical course/severity of hospitalized patients infected by SARS-CoV-2 can be different in the various seasons.. OBJECTIVES: to understand whether there were differences in severity of COVID-19 in patients who had contracted the infection in winter versus those infected in spring/summer. DESIGN: observational retrospective cohort study. SETTING AND PARTICIPANTS: from the administrative database of the SARS-CoV-2 surveillance system and that of hospital discharge, a cohort of patients (8,221, 653 of which were hospitalized) who tested positive to the RT-PCR test for SARS-CoV-2 between 01.12.2020 and 31.07.2021 in the Grosseto province (Tuscany Region, Central Italy) was selected and analysed. MAIN OUTCOME MEASURES: hospitalization rate and length, continuous positive airway pressure (CPAP) or non-invasive ventilation (NIV) use, Intensive Care Unite (ICU) admissions, intra-hospital mortality and PaO2/FiO2 values were measured and compared between subjects infected in winter and those who developed COVID-19 in spring/summer. Viral load (cycle threshold, Ct), vitamin D, serum ferritin, IL-6, procalcitonin, D-dimer, and C-reactive protein measured in the two periods were also compared. RESULTS: in the considered months, the hospitalization rate among 8,221 patients with COVID-19 was 8%: 370 (8.5%) individuals were hospitalized in winter and 283 (7,3%; p=0.31) in spring/summer; 62 (16.8%), 88 (23.8%), and 63 (17%) in winter and 28 (9.9%), 40 (14.1%), and 36 (12.7%) in spring/summer were admitted in ICU (p=0.01), used CPAP/NIV (p=0.002) and died (p=0.13), respectively. Hospitalization days were 14.5±11.6 in winter and 10.3±8.84 in spring/summer (p=0.001), while minimum PaO2/FiO2, measured during hospital stays was 123.2±38.6 in spring/summer and 112.6±40.8 in winter (p=0.054). Multivariate analysis (adjusted for all confounding factors) also confirmed reduced risks of having ICU admissions (0.53; 95%CI 0.32;0.88; p=0.01) and of using CPAP/NIV (0.48; 95%CI 0.32;0.75; p=0.001) in spring/summer when compared to winter. Hospitalization days and minimum PaO2/FiO2 were also lower in spring/summer (ß= -3.9; 95%CI -5.5;-2.2; p=0.001) and winter (ß= -17; 95%CI -0.93;35; p=0.06), respectively. The adjusted hazard ratio of mortality in winter, obtained with a Cox model, was higher of about 38% compared to spring/summer. No Ct values (viral load) differences were found either in winter (19.45±6.18) or spring/summer (20.3±6.7; p=0.343). IL-6, ferritin, procalcitonin, D-dimer were similar. Conversely, CRP was lower whereas vitamin D was higher in the warmer seasons. CONCLUSIONS: COVID-19 may be less severe during spring/summer in hospitalized patients. This does not seem to be influenced by different SARS-CoV-2 viral load in the different periods considered. C-reactive protein was found to be lower whereas vitamin D higher in the warmer months. It can be hypothesized that higher levels of vitamin D in spring/summer, compared to winter, may be associated to a positive modulation of COVID-19 induced inflammation with a possible disease severity reduction during spring/summer.

JAK inhibition reduces SARS-CoV-2 liver infectivity and modulates inflammatory responses to reduce morbidity and mortality.

Using AI, we identified baricitinib as having antiviral and anticytokine efficacy. We now show a 71% (95% CI 0.15 to 0.58) mortality benefit in 83 patients with moderate-severe SARS-CoV-2 pneumonia with few drug-induced adverse events, including a large elderly cohort (median age, 81 years). An additional 48 cases with mild-moderate pneumonia recovered uneventfully. Using organotypic 3D cultures of primary human liver cells, we demonstrate that interferon-α2 increases ACE2 expression and SARS-CoV-2 infectivity in parenchymal cells by greater than fivefold. RNA-seq reveals gene response signatures associated with platelet activation, fully inhibited by baricitinib. Using viral load quantifications and superresolution microscopy, we found that baricitinib exerts activity rapidly through the inhibition of host proteins (numb-associated kinases), uniquely among antivirals. This reveals mechanistic actions of a Janus kinase-1/2 inhibitor targeting viral entry, replication, and the cytokine storm and is associated with beneficial outcomes including in severely ill elderly patients, data that incentivize further randomized controlled trials.