Study: Omicron much more infectious in US preschoolers than Delta
A new study in JAMA Pediatrics shows the Omicron variant has caused six to eight times the rate of Omicron infections in US preschoolers as the Delta variant, but cases were less severe with Omicron.
The study looked at outcomes in US children ages 4 and younger—the last group eligible for vaccination in the country. Outcomes were emergency room visits, hospitalizations, intensive care unit (ICU) admissions, and mechanical ventilation use within 14 days of COVID-19 diagnosis.
Using electronic health records, researchers at Case Western University compared 22,772 children infected with Omicron in late December and late January of this year, to more than 66,000 children infected with the Delta variant between Sep 1 and Nov 15 of 2021, and 10,496 infected with the Delta 2 variant between Nov 16 and Nov 30, 2021. None of the children had previously documented SARS-CoV-2 infections.
Monthly incidence among this cohort was 2.4 to 5.6 cases per 1,000 persons per day in December 2021, and jumped to a peak of 8.6 cases per 1,000 persons per day in the first half of January 2022. Pediatric patients with Omicron were on average a bit younger—1.5 years of age versus 1.7 years—and had fewer comorbidities.
But despite causing less severe illness, pediatric hospitalizations were highest in January of this year, because Omicron caused 10 to 15 times the rate of cases than Delta. There were fewer than 10 deaths in each of the three study cohorts.
"The major conclusion to our research was that many more children were infected with Omicron when compared to Delta, but the children who are infected are not impacted as severely as were children infected with the Delta variant," said Pamela Davis, PhD, an author and researcher at the Case Western Reserve School of Medicine, in a university press release.
Apr 1 JAMA Pediatr study
Apr 1 Case Western University press release
Early convalescent plasma may cut COVID-19 hospital cases in half
Early treatment with plasma derived from COVID-19 survivors may reduce disease progression in infected adult outpatients and reduce hospital cases by more than half, according to a multicenter randomized, controlled trial last week in The New England Journal of Medicine (NEJM).
Johns Hopkins Medicine researchers led the double-blind study evaluating the effectiveness and safety of SARS-CoV-2 antibody-rich convalescent plasma among 592 nonhospitalized patients who received the treatment within 9 days of symptom onset and 589 who received a placebo infusion from Jun 3, 2020, to Oct 1, 2021.
Hospitalization within 28 days of infusion occurred in 17 of 592 convalescent plasma recipients (2.9%) and 37 of 589 controls (6.3%) (absolute risk reduction, 3.4 percentage points; 95% confidence interval, 1.0 to 5.8), corresponding to a relative risk reduction of 54%.
The study authors cautioned that efficacy among vaccinated participants couldn't be determined because 53 of the 54 hospitalized participants were unvaccinated, and 1 was partially vaccinated. Sixteen severe or medically significant adverse events (7 in the treatment group and 9 controls) occurred in nonhospitalized participants. Trial results were first presented on the medRxiv preprint server on Dec 21, 2021, before peer review.
In a Johns Hopkins news release, lead study author Dan Sullivan, MD, said the best use for convalescent plasma, which is relatively low-cost, is for early outpatient treatment when treatments such as monoclonal antibodies or other effective drugs are not readily available (as in low- and middle-income countries) or where SARS-CoV-2 variants have become resistant to those treatments.
"Based on our findings and conclusions, which are now validated through the peer-review process—we encourage health care professionals to keep SARS-CoV-2 antibody-rich blood plasma available in their blood banks as part of the treatment arsenal against early-stage COVID-19,” Sullivan said.
The US Food and Drug Administration authorized the use of convalescent plasma as a treatment for hospitalized COVID-19 patients on Aug 23, 2020, and revised it on Dec 28, 2021, to include inpatients and outpatients with compromised immune systems. But studies published in October 2020 and March 2021 and a January 2022 review showed no benefit for the intervention.
Mar 30 NEJM study
Mar 30 Johns Hopkins news release
