ImportanceClinical manifestations of SARS-CoV-2 variants have not been systematically compared in children.ObjectiveTo compare symptoms, emergency department (ED) chest radiography, treatments, and outcomes among children with different SARS-CoV-2 variants.Design, Setting, and ParticipantsThis multicenter cohort study was performed at 14 Canadian pediatric EDs. Participants included children and adolescents younger than 18 years (hereinafter referred to as children) tested for SARS-CoV-2 infection in an ED between August 4, 2020, and February 22, 2022, with 14 days of follow-up.Exposure(s)SARS-CoV-2 variants detected on a specimen collected from the nasopharynx, nares, or throat.Main Outcomes and MeasuresThe primary outcome was presence and number of presenting symptoms. The secondary outcomes were presence of core COVID-19 symptoms, chest radiography findings, treatments, and 14-day outcomes.ResultsAmong 7272 participants presenting to an ED, 1440 (19.8%) had test results positive for SARS-CoV-2 infection. Of these, 801 (55.6%) were boys, with a median age of 2.0 (IQR, 0.6-7.0) years. Children with the Alpha variant reported the fewest core COVID-19 symptoms (195 of 237 [82.3%]), which were most often reported by participants with Omicron variant infection (434 of 468 [92.7%]; difference, 10.5% [95% CI, 5.1%-15.9%]). In a multivariable model with the original type as the referent, the Omicron and Delta variants were associated with fever (odds ratios [ORs], 2.00 [95% CI, 1.43-2.80] and 1.93 [95% CI, 1.33-2.78], respectively) and cough (ORs, 1.42 [95% CI, 1.06-1.91] and 1.57 [95% CI, 1.13-2.17], respectively). Upper respiratory tract symptoms were associated with Delta infection (OR, 1.96 [95% CI, 1.38-2.79]); lower respiratory tract and systemic symptoms were associated with Omicron variant infection (ORs, 1.42 [95% CI, 1.04-1.92] and 1.77 [95% CI, 1.24-2.52], respectively). Children with Omicron infection most often had chest radiography performed and received treatments; compared with those who had Delta infection, they were more likely to have chest radiography performed (difference, 9.7% [95% CI, 4.7%-14.8%]), to receive intravenous fluids (difference, 5.6% [95% CI, 1.0%-10.2%]) and corticosteroids (difference, 7.9% [95% CI, 3.2%-12.7%]), and to have an ED revisit (difference, 8.8% [95% CI, 3.5%-14.1%]). The proportions of children admitted to the hospital and intensive care unit did not differ between variants.Conclusions and RelevanceThe findings of this cohort study of SARS-CoV-2 variants suggest that the Omicron and Delta variants were more strongly associated with fever and cough than the original-type virus and the Alpha variant. Children with Omicron variant infection were more likely to report lower respiratory tract symptoms and systemic manifestations, undergo chest radiography, and receive interventions. No differences were found in undesirable outcomes (ie, hospitalization, intensive care unit admission) across variants.

Summary. Relaxin was extracted from the ovaries of pregnant rats. Material possessing uterine relaxing activity in vitro was eluted in three peaks from Sephadex G.50 columns. The 'G3 peak' material eluting in a position comparable to that of porcine relaxin inhibited myometrial activity of rats in vivo, improved the rate of rise of pressure of intrauterine pressure cycles in vivo, and, when administered to rats following progesterone and oestrogen priming, increased the distensibility of the cervix in vitro. This material also stimulated inter-pubic ligament formation in the mouse. This rat relaxin material therefore exhibits biological actions in the rat similar to those previously assigned to porcine relaxin.

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