Risk of COVID-related syndrome lower in kids after breakthrough Omicron
The risk of COVID-19–related multisystem inflammatory system in children (MIS-C) was significantly lower among vaccinated versus unvaccinated Danish children after infection with the Omicron variant rather than with previous strains, according to a research letter published yesterday in JAMA Pediatrics.
A team led by Aarhus University researchers used Danish COVID-19 surveillance registries to prospectively study 0- to 17-year-old patients diagnosed as having MIS-C at all of the country’s 18 Danish pediatric healthcare units from Jan 1 to Mar 15, 2022. They were infected from Jan 1 to Feb 1, 2022, when Omicron made up 95% of variants in that country.
Of the 583,618 children and adolescents estimated to have had COVID-19, 267,086 were vaccinated. Among those with COVID, 1 vaccinated and 11 unvaccinated MIS-C patients were identified.
Amid Omicron, the risk of MIS-C was 89% lower in vaccinated versus unvaccinated patients (risk ratio [RR], 0.11; 95% confidence interval [CI], 0.01 to 0.83). The risk was 88% lower in unvaccinated patients during Omicron than during the Delta wave (RR, 0.12; 95% CI, 0.06 to 0.23) and 86% lower than during the wild-type virus wave (RR, 0.14; 95% CI, 0.07 to 0.29). There was no difference in MIS-C signs and symptoms between Omicron and previous variants.
The authors said the findings may be attributed to Omicron’s reduced ability to cause hyperinflammation, because it is less likely to trigger the immune system.
“The lower risk could also partly be explained by a reduced risk after reinfection, although only 6% of our included infected individuals had confirmed reinfection, and such a reduced risk after reinfection has not yet been reported,” they wrote, acknowledging that the study was limited by the few MIS-C patients.
The lower risk of MIS-C after Omicron reinfection in vaccinated patients may also be due to the high effectiveness of the COVID-19 vaccine, the researchers said. “This may be caused by vaccine-induced modulation of the immune system, rendering it less prone to cause hyperinflammation after SARS-CoV-2 infection,” they wrote.
Jun 8 JAMA Pediatr research letter
Avian flu turns up in Washington, DC, and Arizona
Marking the first highly pathogenic avian flu detection in the nation’s capital, the National Park Service (NPS) yesterday said the virus has been detected in mallard ducklings in the Lincoln Memorial’s reflecting pool. Also, Arizona reported its first detection in wild birds, cormorants at a park in Scottsdale.
The NPS said avian flu had been detected earlier in domestic and wild birds in states surrounding Washington, DC—Delaware, Maryland, and Virginia. It said though the virus poses a low risk to humans, visitors should avoid handling live or dead birds or coming in contact with their droppings.
In Arizona, highly pathogenic H5N1 was found in three nestling cormorants found dead in Eldorado Park in Scottsdale, according to a statement from the Arizona Game and Fish Department. So far, no outbreaks have been reported in Arizona poultry.
In related developments, federal officials today reported four more outbreaks in poultry in three states, all involving backyard flocks. According to updates from the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS), Indiana reported two outbreaks in Allen County, Oregon reported an outbreak in Polk County, and Washington reported another in King County.
Though outbreaks in poultry have slowed, the virus continues to be reported broadly across the United States. APHIS continues to report dozens of H5N1 detections in wild birds each week, with 1,422 reported since the middle of January.
Jun 8 NPS statement
Jun 8 Arizona Game and Fish statement
USDA APHIS poultry outbreak updates
Connecticut reports fatal Powassan virus infection
Connecticut this week reported its second Powassan virus case of the year, involving a patient from New London County in the southeastern corner of the state who died from her infection.
In a statement, the Connecticut Department of Health (CDH) said the woman in her 90s and became ill in early May, about 2 weeks after she was bitten by a tick. Over the next 2 weeks, her condition worsened, and she died on May 17. Lab tests conducted by the Centers for Disease Control and Prevention (CDC) confirmed antibodies to Powassan virus.
Connecticut’s first case of the year was in a man in his 50s from Windham County in the state’s northeastern corner who was sick in late March after a tick bite. He was hospitalized with neurologic symptoms but was discharged and recovered at home.
From 2017 through 2021, Connecticut reported 12 Powassan virus cases, 2 of them fatal. Last year, the state reported 3 of those cases.
The disease, mainly spread by black-legged (deer) ticks, causes symptoms that range from headache to encephalitis. There is no treatment. Most cases are reported from Great Lakes and northeastern states. The CDC typically receives reports regarding a dozen or more Powassan virus cases affecting the nervous system each year, with the most—39 cases—in 2019.
Jun 7 CDH statement