A study yesterday in JAMA Network Open based on outcomes seen among Singaporean children ages 4 years and younger showed good protection for two doses of monovalent mRNA COVID vaccines during an Omicron surge.

The authors said the findings support vaccinating this age-group, despite low incidence of severe disease or hospitalization.

The study was conducted from October 1, 2022, to March 31, 2023, after all Singaporean children ages 1 to 4 had been vaccinated with mRNA two-dose vaccines in a community vaccination campaign following approval of vaccines for this age-group in August 2022.

The 6-month study period coincided with an Omicron XBB surge in Singapore, during which schools remained open, mask wearing was optional, and close contacts of COVID-19 cases were allowed to remain in school if well.

63% to 75% effective in preventing infections

A total of 121,628 children (median age, 3.1 years) were included in the study, contributing 21,015 ,956 person-days of observation. A total of 45,693 children (37.6%) had a prior SARS-CoV-2 infection, with most having had prior infection during the earlier Omicron BA.1/2 wave, the authors said.

In kids with no previous COVID-19, vaccination was 63.3% effective in protecting against infection. Protection was higher, 74.6%, in those with a documented prior infection. Data were insufficient to assess vaccine effectiveness in fully vaccinated children with prior SARS-CoV-2 infection, the authors said.

There were no hospitalizations among fully vaccinated children, and no deaths were reported during the study.

Rapid increases in pediatric COVID-19 infections coinciding with periods of high community transmission may still place health care systems under strain.

Though vaccinating children under the age of 5 is debatable, the authors said, "Rapid increases in pediatric COVID-19 infections coinciding with periods of high community transmission may still place health care systems under strain."

A genomic study conducted in Ghana found that the most worrisome antimicrobial resistance (AMR) genes in Klebsiella bacteria were primarily found in clinical settings, African and European researchers reported yesterday in The Lancet Microbe.

For the One Health study, researchers collected samples of Klebsiella bacteria from hospitals, residential areas, and farms in Tamale, Ghana. Their aim was to capture as many rural and urban points of potential Klebsiella transmission within and around the city, then use whole-genome sequencing to assess the prevalence of AMR genes in different settings.

While Klebsiella is a major human pathogen, the authors note that is also an "ecological generalist" that lives in many environments and can spread AMR genes in different settings. They wanted to see how different sectors might contribute to the public health burden of drug-resistant Klebsiella pneumoniae, particularly in a low- and middle-income country (LMIC) with poor sanitation and hygiene, where people live near animals.

AMR genes concentrated in clinical sources

Among the 620 Klebsiella-positive samples collected around Tamale, 27% were from hospital patients, 23% were from water, 14% from environmental surfaces, and 13% from farm animals. From these samples, 573 Klebsiella isolates were sequenced, 370 of which (65%) were Klebsiella pneumoniae.

Although AMR-associated genes were observed relatively frequently in non-clinical sources (0.7 AMR gene classes per isolate), they were concentrated in clinical sources, with the highest levels found in hospital patients (6.5 AMR gene classes per isolate) and hospital environment sources (4.8 AMR classes per isolate). Extended-spectrum beta-lactamase genes were mainly found in hospital patients (14 of 22 isolates) and the hospital environment (3 of 5 isolates). Genes encoding carbapenemases were found in only 2 clinical isolates.

"Overall, the available evidence indicates that clinical settings are the hubs of both AMR and its successful transmission, even in LMICs, which provides crucial information for designing future interventions to curb the success of multidrug-resistant Klebsiella," the study authors concluded.

As part of an ongoing rise in detections this month, Colorado and North Dakota reported the reappearance of highly pathogenic avian flu in poultry, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) said in its latest updates.

Both events involved backyard poultry, but a few other states have reported recent outbreaks on commercial farms. Colorado’s outbreak occurred in Weld County at a location housing 30 birds.

In North Dakota, the virus struck a 10-bird flock in Williams County. State animal health officials in a statement said though detections in wild birds have declined, the virus continues to be a source of disease among domestic birds.

Condor vaccination results

In other US developments, the US Fish and Wildlife Service yesterday reported early findings on a highly pathogenic avian influenza vaccine trial in endangered California condors, following an outbreak in the spring.

Following two doses, 60% had an antibody response expected to provide partial protection against death, and 10% had titers expected to protect fully against death. Results are pending on the one-dose and control groups.

Officials said that, based on the findings, 14 more condors that are slated for release will receive the two-dose series.

H5N1 outbreaks in two European countries

Elsewhere, Norway and Poland reported H5N1 outbreaks in poultry, both in backyard flocks, according to notifications from the World Organization for Animal Health (WOAH).

Poland’s outbreak, its first since July, occurred at a location that has 80 birds in West Pomerania province in the country’s northwest. Norway’s outbreak, its first since February, involved a location with 19 birds in Trogs og Finnmark County in the far north.