By third quarter 2022, an estimated 96.4% of US blood donors had antibodies against COVID-19 from a previous infection or vaccination, including 22.6% from infection alone and 26.1% from vaccination alone, with 47.7% having both (hybrid immunity), according to a study published today in Morbidity and Mortality Weekly Report.

Led by researchers from the Centers for Disease Control and Prevention (CDC), the study involved antibody testing of blood samples from 72,748 donors aged 16 and older collected from April to June 2021.

Percentage with antibodies rose over time

From April to June 2021, an estimated 68.4% of blood donors had SARS-CoV-2 antibodies from previous infection or vaccination, including 47.5% from vaccination alone, 12.0% from infection alone, and 8.9% from both.

From January to March 2022, 93.5% of donors had antibodies from previous infection or vaccination, including 39.0% from vaccination alone, 20.5% from infection alone, and 34.1% from both.

During July to September 2022, 96.4% of participants had antibodies from previous infection or vaccination, including 26.1% from vaccination alone, 22.6% from infection alone, and 47.7% from both. From July to September 2022, the prevalence of infection-induced immunity was 85.7% among unvaccinated participants and 64.3% among their vaccinated peers.

From July to September 2022, donors aged 65 years and older had the lowest prevalence of hybrid immunity (36.9%), and those aged 16 to 29 years had the highest (59.6%). From January through June 2022, COVID-19 incidence among unvaccinated participants was 21.7%, compared with 13.3% among the vaccinated. And from April to September 2022, the incidence among unvaccinated donors was 28.3%, compared with 22.9% among their vaccinated peers.

The incidence of first COVID-19 infections was higher among younger than older participants. "Lower prevalences of infection-induced and hybrid immunity could further increase the risk for severe disease in this group, highlighting the importance for adults aged ≥65 years to stay up to date with COVID-19 vaccination and have easy access to antiviral medications," the researchers wrote.

A team of US researchers reported benchmarking data for outpatient prescribing in pediatric settings yesterday in the Journal of the Pediatric Infectious Diseases Society.

For the study, institutions from the Sharing Antimicrobial Reports for Pediatric Stewardship OutPatient (SHARPS-OP) Collaborative were invited to contribute quarterly aggregate reports on outpatient oral antibiotic prescriptions in patients under 20 years of age from January 2019 through June 2022. Outpatient settings included emergency departments (EDs), urgent care centers (UCCs), primary care clinics (PCCs), and telehealth encounters. Each institution then received a benchmark report comparing their institution with the others that provided data.

Benchmarking metrics included the percentages of all acute encounters resulting in an antibiotic prescription, acute respiratory infection (ARI) encounters resulting in an antibiotic prescription, encounters resulting in an amoxicillin prescription (the "amoxicillin index"), and encounters resulting in an azithromycin prescription (the "azithromycin index"). The researchers also collected rates of antibiotic courses that were 7 days or shorter and 10 days or shorter.

Overall, antibiotics were prescribed in less than one fifth of all acute encounters. Antibiotic prescribing for ARI varied between settings, with the highest rates observed in UCCs (40.2%) and the lowest in telehealth (19.1%), though there was substantial variation in prescribing for ARI encounters via telehealth. The amoxicillin index was highest for EDs (76.2%) and lowest for telehealth (55.8%), while the azithromycin index was similar for EDs, UCCs, and PCCs (3.8%, 3.7%, and 5.0% respectively). Antibiotic duration of 7 days or less also varied substantially (46.4% for EDs, 27.8% for UCCs, 23.7% for telehealth, and 16.4% for PCCs).

We will continue to collect and report quarterly antibiotic use to trend over time, with the goal of identifying high-performers and potential 'appropriate' levels for our metrics.

The study authors say they hope to use the benchmarking data to develop national standards for pediatric ARI prescribing.

"We will continue to collect and report quarterly antibiotic use to trend over time, with the goal of identifying high-performers and potential 'appropriate' levels for our metrics, and empowering institutions with data to develop approaches to reduce inappropriate antibiotic use in the patients cared for at their institutions," they wrote.

• Tanzania today declared the end of its first Marburg virus outbreak, which was declared on Mar 21 and sickened nine people, six of them fatally. The cases were limited to the Kagera region, located in the country's northwest. The last patient tested negative for a second time on Apr 19, which started a 42-day countdown to the end of the outbreak. Matshidiso Moeti, MBBS, head of the World Health Organization (WHO) African regional office in a statement said quick actions from Tanzania's government and support from the WHO and its partners played key roles in ending the outbreak. In a statement today, WHO Director-General Tedros Adhanom Ghebreyesus said, "The outbreak in Equatorial Guinea is also expected to be declared over next week, if no further cases are detected."
• Afghanistan has reported a third wild poliovirus type 1 (WPV1) case for the year, putting it above the total of two reported for 2022, according to the latest update from the Global Polio Eradication Initiative (GPEI). The case from Nangarhar province was reported recently in the media, and a new media report today noted a fourth WPV1 case, involving a 4-year-old boy from the same province with a May 16 paralysis onset. Elsewhere, the Central African Republic reported one more circulating vaccine-derived poliovirus type 2 (cVDPB2) case, in a patient from RS4 district, bringing the country's total for the year to seven.
• In an update on the global cholera situation yesterday, the WHO said no new countries have reported outbreaks since its last update on May 11, keeping the total at 24. It noted, however, that the geographic spread continues in the Horn of Africa, especially in the Mandera triangle where the Ethiopian, Kenyan, and Somalian borders meet. The agency said the global capacity to battle multiple outbreaks continues to feel strain, especially as countries manage multiple disease threats. The WHO said given those factors and the lack of vaccines and other resources, the global risk remains very high.