A recent study in The Journal of Gerontology analyses Medicare data from 3,588,671 Medicare beneficiaries diagnosed as having COVID-19 from October 2021 to March 2023 and finds that 3.9% of beneficiaries—or about 140,000 people—were diagnosed with long COVID after experiencing symptoms for at least 1 year.

The authors also estimated the risk of developing long COVID based on the number of COVID-19 vaccine doses administered prior to the index date, using Medicare Part B claims and pharmacy records.

A greater number of COVID-19 vaccine doses was associated with a reduced relative rate of Long COVID compared to no COVID-19 vaccine dose

"In both unadjusted and fully adjusted models, a greater number of COVID-19 vaccine doses was associated with a reduced relative rate of Long COVID compared to no COVID-19 vaccine dose," the authors wrote. 

Multiple vaccine doses lowered risk of long COVID

Overall, beneficiaries with four or more COVID-19 vaccine doses had a 39% lower adjusted rate of long COVID relative to beneficiaries without a prior dose (adjusted hazard ratio, 0.61; 95% confidence interval [CI], 0.60 to 0.62).

"Long COVID diagnoses were relatively common, occurring in nearly 1 in 25 Medicare beneficiaries, but especially in those with certain chronic conditions and without prior COVID-19 vaccine doses," the authors concluded. "COVID-19 vaccine doses may mitigate long COVID risk through reducing viral load and the severity of natural infection, but additional causal inference studies are needed to confirm these hypotheses."

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed a third H5N1 avian flu outbreak at a large layer farm in Arizona, affecting nearly 1.4 million birds.

Since the middle of May, the virus has hit three of the state’s large layer farms, all in Maricopa County, leading to a loss of more than 5 million birds. The outbreak wiped out about 95% of the birds at Hickman Family Farms’ facilities, and has shuttered all of the company’s West Valley farms, according to a local media report.

Canadian ostriches had novel reassortant

Ostriches at a farm in British Columbia embroiled in a controversy over culling were infected with a novel H5N1 reassortant that included the D1.3 genotype, according to a recent statement from the Canadian Food Inspection Agency (CFIA). The reassortant hadn’t been detected before in Canada, but was identified in March in a serious infection in an Ohio poultry worker.

The outbreak at the ostrich farm was initially reported earlier this spring, and the company has not adhered to Canada’s rules about culling and quarantine, amid a public uproar over the federal laws that require that the birds be destroyed. 

Instituting routine testing of migrants for certain infectious diseases leads to earlier diagnoses and treatment, improving health outcomes and lowering the risk of onward community spread, suggests an observational UK study published late last week in eClinicalMedicine.

The researchers gauged the efficacy of testing migrants for tuberculosis (TB) with an interferon gamma release assay, HIV, hepatitis B virus (HBV) with surface antigen testing, and hepatitis C virus (HCV) with antibody testing and polymerase chain reaction (PCR) testing. The team tested patients when they first registered with general practices (GPs) in Leicester and analyzed test positivity rates, numbers of new diagnoses, and other healthcare data from 2016 to 2019.

"While some testing for infectious disease may take place at the discretion of individual GPs currently, this is neither the norm and typically happens in silo," senior author Manish Pareek, of the University of Leicester, said in a university news release. 

Vast majority completed treatment

Of 4,004 migrants referred for testing, the test positivity rate was 0.5% for HIV, 3.3% for HBV, 0.2% for HCV, and 19.4% for TB. Among the 437 TB patients, 7% had active disease, and 92% had latent infections. 

Idaho reports three new chronic wasting disease (CWD) cases in white-tailed deer in the Panhandle Region.

Idaho Fish and Game (IFG) said the infections were identified during the 2024 deer-hunting season in the Unit 1 CWD-Management Zone, which includes Coeur d'Alene, east of Spokane, Washington. The new detections push the total number of CWD-positive free-ranging deer in northern Idaho to six since the first identification in July 2024.

Low estimated prevalence

In total, 936 white-tailed deer were tested for CWD in Unit 1 during the 2024 hunting season, a large increase from 2023. 

Early detection of CWD is critical, as it creates opportunities to take action to slow the rate of spread of the disease.

"Relative to many other states, the current estimated prevalence rate (less than 1%) of the disease in the management zone is low," IFG wrote. "Low prevalence rates suggest that Fish and Game in collaboration with hunters detected the disease early. Early detection of CWD is critical, as it creates opportunities to take action to slow the rate of spread of the disease." 

During the 2025-26 Big Game Season Setting process, IFG staff proposed five new controlled hunts for white-tailed deer in Unit 1, which the Fish and Game Commission adopted in March 2025. 

"Between the addition of 100 extra antlered white-tailed deer tags, addition of 1,000 extra antlerless white-tailed deer tags and reduction of 750 antlerless white-tailed deer tags in Unit 1, there is a net increase of 350 extra deer tags available in Unit 1, with a targeted focus to increase harvest within the CWD management zone," IFG wrote.

CWD, which affects cervids such as deer, elk, and moose, is caused by infectious misfolded proteins called prions. The fatal neurodegenerative disease spreads through cervid-to-cervid contact and environmental contamination. There is no vaccine or cure.