Although a number of studies have found that a diabetes drug called metformin reduces the risk of long COVID, new research finds that it does not reduce symptoms of the condition.

There’s also no benefit to treating people with long COVID with ursodeoxycholic acid (UDCA), also known as ursodiol, which is used is to treat gallstones and liver disease, according to the study, published this week in Annals of Internal Medicine.

There are no proven treatments for long COVID, which has affected millions of people since the pandemic began six years ago. 

In the United States, about 8% of adults have experienced long COVID. The chronic condition, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), is associated with a wide range of symptoms, including profound exhaustion, chronic cough, and memory issues commonly known as “brain fog.”

No difference in recovery rates compared with placebo

The double-blind, placebo-controlled, randomized clinical trial of 396 people was conducted at two hospitals in South Korea from July 2024 to April 2025 and led by researchers at the University of Ulsan College of Medicine in Seoul. Patients were randomly assigned to take metformin, UDCA, or a placebo for 14 days. The primary outcome was PASC recovery at eight weeks.

Although 67% of study participants reported recovery after eight weeks, there was no statistically significant difference in recovery rates among patients who received medication and those given a placebo.

In people whose symptoms improved over eight weeks, blood tests showed decreases in key immune system proteins called cytokines, which are often related to inflammation. Those findings “highlighted the need for further studies to support the development of targeted therapies addressing immune dysregulation in long COVID,” the study authors wrote.

An analysis of factors contributing to excess US tuberculosis (TB) cases and deaths from the onset of the COVID-19 pandemic in 2020 and projections up to 2035 estimates nearly 3,000 more cases and more than 1,100 TB deaths than expected.

A team led by Harvard University researchers identified four mechanisms that may have contributed to TB trends from 2020 to 2023: immigration, respiratory contact rates, rates of accurate diagnosis and treatment initiation, and death rates for TB patients. The researchers used a Bayesian approach to synthesize evidence on mechanism changes during the pandemic and how they might have combined to produce the observed TB trends.

They also simulated a no-pandemic counterfactual scenario that assumed that mechanisms followed prepandemic patterns, estimated TB outcomes tied to the pandemic until 2035 to capture lagged effects, and assessed other scenarios to estimate the effect of each mechanism.

TB “notifications and deaths in the United States fluctuated substantially during the coronavirus disease 2019 (COVID-19) pandemic,” the study authors wrote. “We analyzed multiple data sources to understand the factors contributing to these changes and estimated future TB trends.”

The findings were published late last week in Clinical Infectious Diseases.

Factors may continue to influence TB trends over time

From 2020 to 2035, the team estimated 2,784 excess TB cases and 1,138 deaths in the United States linked to changes occurring during the pandemic. Mechanisms had offsetting effects—decreases in TB diagnoses rates led to more TB deaths and notifications, while reductions in contact rates reduced TB deaths and notifications.

This study used mathematical modeling to explore the impact of COVID-19 pandemic on TB in the United States, finding increases in both TB notifications and TB deaths during 2020–2035.

Initially, immigration changes lowered TB deaths but raised deaths and notifications over time. Higher TB mortality rates increased TB deaths but decreased TB notifications.

“This study used mathematical modeling to explore the impact of COVID-19 pandemic on TB in the United States, finding increases in both TB notifications and TB deaths during 2020–2035,” the study authors concluded. “Although direct impacts of the COVID-19 pandemic occurred between 2020 and 2023, these changes may continue to influence TB incidence and mortality in future years.”

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed at least 20 H5N1 avian flu outbreaks on commercial poultry facilities this past week, including five detections on facilities in LaGrange County, Indiana. 

Also hit this week was a commercial broiler production facility in Carolina County, Maryland, with 95,600 birds affected. Commercial table egg layers had the largest outbreaks reported to APHIS. A facility in Hyde County, North Carolina, had 3.2 million birds affected, and a facility in Jefferson County, Wisconsin, had 1.2 million birds involved. 

Also of note, two live bird markets, one in Orange County, Florida, and one in Kings County, New York, reported bird flu outbreaks affecting a total of 870 birds. 

In the past 30 days, avian flu has been confirmed among 67 flocks, including 36 commercial flocks and 31 backyard flocks. A total of 11.54 million birds have been affected. 

In wild bird news, APHIS reported about 60 detections in the past week, including 10 each in Colorado and Ohio. Red-tailed hawks were the most commonly hit bird in Colorado.