Risk of severe disease much lower with Omicron COVID variant than Delta
The risk of hospitalization, intensive care unit (ICU) admission, and death was much lower among more than 9,000 Canadian COVID-19 patients infected with the Omicron variant than among matched Delta patients, according to a study published yesterday in JAMA.
The risk of hospitalization or death with Omicron was 41% of—and the risk of death was one-tenth of—that of Delta.
Public Health Ontario researchers retrospectively studied the outcomes of all COVID-19 patients in the province with illness onset from Nov 22 to Dec 24, 2021, amid the Omicron surge but before the emergence of the Omicron BA.2 subvariant. Median follow-up was 24 days.
Omicron cases were identified using whole-genome sequencing or S gene target failure testing, and Delta cases were identified through these methods or as those not identified as Omicron.
Among 37,296 Omicron cases, 9,087 were matched in a 1:1 ratio with Delta cases. Fifty-three Omicron patients (0.6%) were hospitalized, and 3 (0.3%) died, compared with 129 hospitalizations (1.4%) and 26 deaths (0.3%) among Delta patients.
The hazard ratio (HR) for hospitalization or death among Omicron patients relative to Delta patients was 0.41 (95% confidence interval [CI], 0.30 to 0.55) (0.33 in a sensitivity analysis [95% CI, 0.19 to 0.56]). The HR for ICU admission or death was 0.19 (95% CI, 0.09 to 0.39), while it was 0.12 (95% CI, 0.04 to 0.37) for death.
Estimates of Omicron severity stratified by age, sex, and vaccination status all indicated decreased severity.
"The results align with findings from South Africa, Scotland, and England, all of which have demonstrated substantial decreases in risk associated with Omicron," the researchers wrote. "While severity may be reduced among Omicron cases, the absolute number of hospitalizations and the effects on health care systems are likely to be significant due to the elevated incidence of Omicron."
Feb 17 JAMA research letter
California reports H1N2v flu case
California has reported a variant H1N2 (H1N2v) flu case in an adult who had direct contact with pigs, the US Centers for Disease Control and Prevention (CDC) said today in its weekly FluView report.
The patient wasn't hospitalized and has recovered. Some respiratory illnesses were reported in some of the patient's contacts, but the CDC said the events occurred during a period of high respiratory illness activity, and no specimens were collected for testing. No ongoing human-to-human transmission of H1N2v has been linked to the case.
So far, three novel influenza A cases have been reported to the CDC this flu season. Earlier reports involved an H3N2v case in Ohio and an H1v (neuraminidase not determined) case in Oklahoma.
In other US flu developments, flu activity increased in some parts of the country last week, though the percentage of outpatient visits for flulike illness remained below the national baseline.
The CDC said overall, sporadic activity continues across the nation, with H3N2 as the dominant strain. Eight states are reporting low flu activity, another marker for clinic visits for flulike illness. Hospitalization rates increased slightly, and no new pediatric flu deaths were reported, keeping the season's total at five.
Feb 18 CDC FluView report
Four babies infected with Salmonella, Cronobacter tied to infant formula
At least four babies have been infected with Salmonella Newport or Cronobacter sakazakii and one has died after drinking infant formula made from a powder produced at Abbott Nutrition's Sturgis, Michigan, facility, the Food and Drug Administration (FDA) said in a news release and outbreak update yesterday.
Three babies tested positive for C sakazakii infections and one for Salmonella, and all were hospitalized. The FDA said, "Cronobacter may have contributed to a death in one case."
The formula from Abbott's Sturgis facility was bought from Sep 6 to Dec 18, 2021, the babies' families reported. The FDA is advising people not to use Similac, Alimentum, or EleCare powdered infant formulas if the first two digits of the product code are 22 through 37 and the code on the container contains K8, SH, or Z2 and the expiration date is Apr 1, 2022, or later.
Scientists with the FDA and CDC are partnering with local officials to investigate the outbreak. "This is an ongoing investigation, and the firm is working with the FDA to initiate a voluntary recall of potentially affected product," the FDA said. "FDA is continuing to investigate and will update this advisory should additional consumer safety information become available."
So far investigators have reported several C sakazakii detections in environmental samples taken at the Sturgis plant. A review of the company's records also indicates environmental contamination with the pathogen and the company's destruction of product because of Cronobacter contamination.
"As this is a product used as the sole source of nutrition for many of our nation's newborns and infants, the FDA is deeply concerned about these reports of bacterial infections," said Frank Yiannas, MPH, FDA deputy commissioner for food policy and response, in the news release. "We want to reassure the public that we're working diligently with our partners to investigate complaints related to these products."
Feb 17 FDA news release and outbreak update
Malawi reports wild poliovirus case linked to Pakistan
In a worrying development, a wild poliovirus type 1 (WPV1) case has been detected in a child in Malawi, Africa's first such case since 2016.
In a statement yesterday, the Global Polio Eradication Initiative (GPEI) said the case involves a 3-year-old girl from Lilongwe, the country's capital, whose paralysis symptoms began on Nov 19, 2021. Tests done by South Africa's National Institute for Communicable Diseases and the US CDC confirmed the WPV1 finding. Sequencing shows that the virus is genetically linked to a WPV1 strain detected in Pakistan's Sindh province.
The case is considered an imported case from Pakistan and does not affect the World Health Organization African region's poliovirus-free certification, which it received in August 2020.
The GPEI is supporting Malawi's response, which includes enhanced surveillance to identify undetected transmission and urgent immunization activities.
Feb 18 GPEI statement
In other polio developments, three countries reported more vaccine-derived polio cases last week: Mozambique, Nigeria, and Somalia. All involved circulating vaccine-derived poliovirus type 2 (cVDPV2).
Mozambique reported two cases, one each in Nampula and Cabo Delgado provinces. Both had onsets in 2021 and are included in its total for last year. Nigeria reported 16 more cases in six states, lifting its total for 2021 to 413. And Somalia reported one new case, which involves a patient from Banadir province, marking its first case of 2022.
Feb 17 GPEI update
USDA reports waterfowl H5 avian flu, including in Connecticut, Georgia
The US Department of Agriculture (USDA) reported 108 more highly pathogenic H5 detections from wild bird surveillance, all on the East Coast, with first detections reported from Connecticut and Georgia.
The USDA's Animal and Plant Health Inspection Service (APHIS) has now reported 247 detections in waterfowl as officials track the virus sampling of both live and hunter-harvested birds. Connecticut's detections are in New London and Middlesex Counties, located in the south-central part of the state. Georgia's detections were from Hart County, in the northeastern part of the state on the South Carolina border.
Other detections include previously affected states, along with newly affected counties within those state, such as Currituck and Craven counties in North Carolina.
Some of the highly pathogenic H5N1 detections on the eastern seaboard have been confirmed as Eurasian H5N1, the strain that is affecting wild birds and poultry in multiple parts of the world. The virus is also confirmed or suspected as triggering outbreaks on five poultry farms in three states, three of them in Indiana.
The USDA said last week that it has expanded surveillance of the virus to all four of the migratory bird flyways that span the US mainland.
APHIS list of highly pathogenic avian flu detections in wild birds