A study of South Korean children suggests antibiotic use in girls in the first year of life may be linked to earlier onset of puberty, researchers reported last week at a joint meeting of the European Society of Paediatric Endocrinology and the European Society of Endocrinology.

In the study, researchers from two university hospitals in South Korea analyzed antibiotic use in 322,731 children (135,232 boys and 187,499 girls) from 0 to 12 months, then followed them until age 10 for the boys and age 9 for the girls. The primary outcome was central precocious puberty (CPP), which for girls is defined as onset of puberty before age 8.

Most children in the study (90.4%) received antibiotics during the first year of life. Compared with those who were prescribed antibiotics after the first year, girls who received antibiotics during the first 3 months had a 23% increased risk of CPP (adjusted hazard ratio [aHR], 1.23; 95% confidence interval [CI], 1.12 to 1.36). Girls who were prescribed antibiotics at 6 to 9 months (aHR, 1.21; 95% CI, 1.10 to 1.32) and 9 to 12 months (aHR, 1.15; 95% CI, 1.04 to 1.26) also had an increased risk of CPP. In addition, girls who were prescribed five or more classes of antibiotics had a higher risk of CPP than those who received two or fewer.

No significant association between early antibiotic use and CPP was observed in boys.

Altering of the gut microbiome could play a role

"Our study adds to growing concerns about how antibiotics given in infancy could affect children’s long-term development—possibly by altering the gut microbiome or hormonal balance—but the reasons behind it are still unclear," study co-author Yunsoo Choe, MD, of Hanyang University Guri Hospital said in a press release. "Understanding these biological mechanisms may help guide safer antibiotic use and inform early-life care strategies for children."

Choe added that earlier research by the same team found that exclusive breastfeeding was associated with a lower risk of CPP, which supports the idea that early-life factors affecting the gut microbiome or endocrine-metabolic pathways may influence puberty development.

A US surveillance study shows that patients with recent COVID-19 infections contributed substantially to increases in hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) bacteremia during the pandemic. The findings were published today in Open Forum Infectious Diseases.

The study, led by researchers from the Centers for Disease Control and Prevention (CDC) and state public health departments, analyzed incident MRSA blood isolates from residents in six states (California, Connecticut, Georgia, Minnesota, New York, and Tennessee) from 2005 through 2022. The researchers wanted to assess the impact of the pandemic on community-associated (CA), healthcare-associated community-onset (HACO), and hospital-onset (HO) MRSA bacteremia.

The data showed that overall MRSA bacteremia incidence per 100,000 population fell from 32.6 in 2005 to 15.7 in 2016, increased to 17.0 in 2019, then ranged from 15.6 t0 16.2 during 2020 to 2022. But the pandemic had a different impact on the incidence of MRSA bacteremia depending on the type.

HACO MRSA incidence fell from 18.7 in 2005 to 10.2 in 2017, increased to 10.8 in 2019, then hit its nadir (9.0) in 2021, while CA MRSA began rising in 2016 but was much lower than predicted from 2020 to 2022. The study authors suggest this drop in incidence may be related to COVID-19 mitigation measures, including closures of schools, gyms, and workplaces; reductions in elective surgeries; and increased use of personal protective equipment among healthcare workers.

Substantial increase in HO MRSA during the pandemic

Incidence of HO MRSA bacteremia during the pandemic followed a different trajectory. After a substantial drop from 2005 through 2014, HO MRSA incidence did not significantly change from 2014 through 2019, then rose by 40% (compared with 2019) in 2021.  From 2020 through 2022, 18.2% to 21.8% of HO MRSA bacteremia cases had recent COVID-19 infections. 

When the researchers excluded cases with recent COVID, incidence fell within the expected range, which the authors say suggests COVID-related hospitalization contributed substantially to the increase in HO MRSA bacteremia.

"This suggests a need for a robust approach to HAI prevention among hospitalized patients with COVID-19 to prevent MRSA bacteremia, a finding that may also be relevant for future pandemic preparedness planning," they wrote.

The US Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) on May 9 recommended a pause in the use of Valneva’s chikungunya vaccine (Ixchiq) in people ages 60 and older while officials investigate severe adverse events, some neurologic and cardiac, in vaccine recipients.

Globally, 17 severe adverse events, 2 of them fatal, have been reported in people ages 62 to 89 years who received the vaccine. Six were from the United States. The FDA said it will conduct an updated risk-benefit assessment.

The FDA approved the vaccine in November 2023 for use in people ages 18 and older at increased risk for the mosquito-borne disease. At its meeting in April, CDC vaccine advisors recommended including a precaution about the vaccine’s use in people ages 65 and older. The FDA and CDC said about 80,000 doses have been given globally.

Ixchiq contains a weakened form of the virus, which may cause symptoms of chikungunya. Federal officials said some of the severe adverse events reported are similar to severe complications from the disease.

In a statement today, Valneva supported precautionary measures that groups have announced. It added that most of the reports involved those who had underlying health conditions or were taking other medications. It said a thorough investigation is critical for sorting whether the adverse events are related to use of the vaccine.

Pause follows earlier alert, regulator actions in Europe

The recommended pause for use in people ages 60 and older follows a CDC alert in early March that said it was investigating five hospitalizations in people ages 65 and older who had received the vaccine. 

In late April, French drug regulators updated their recommendations for Ixchiq after reports of adverse reactions in older people with underlying health conditions who were prioritized the receive the vaccine in a large ongoing outbreak in La Reunion and Mayotte. On May 7, the European Medicines Agency announced that its safety committee had launched a review of Ixchiq in older people and said the vaccine must not be used in people ages 65 and older.

Rockingham County, Virginia, is now part of Virginia's chronic wasting disease (CWD) management area (DMA) 2 after West Virginia detected cases within 10 miles of the county border, the Virginia Department of Wildlife Resources (DWR) notes on its website.

During the 2024-25 deer-hunting season, 8,801 deer in Virginia were tested, and 109 of them (1.2%) were positive for CWD, a fatal neurodegenerative disease of cervids such as deer, moose, and elk. No cases were found outside of the state's four DMAs.

Rockingham County is in northwestern Virginia, near Grant County, West Virginia, which reported its first case in March 2025.

Since CWD was first identified in Virginia in 2009, it has been confirmed in Carroll, Clarke, Culpeper, Fairfax, Fauquier, Floyd, Frederick, Loudoun, Madison, Montgomery, Prince William, Pulaski, Rappahannock, Roanoke, Shenandoah, Tazewell, and Warren counties, the DWR said.

Hunters, others, inform management strategies

The department conducts CWD surveillance and develops management strategies with the help of hunters, taxidermists, and processors, among other groups.

It is illegal to feed deer in Virginia for any reason year-round in all counties within 25 miles of a known CWD-positive deer.

"One important management strategy is to prevent artificially concentrating deer at point sources like feeding sites," the DWR wrote. "As such, it is illegal to feed deer in Virginia for any reason year-round in all counties within 25 miles of a known CWD-positive deer."

CWD is caused by abnormally folded infectious proteins called prions, which spread via saliva, feces, and urine shed by infected deer, as well as through prion-contaminated soil. The disease hasn't been shown to pose a risk to humans or domestic animals, but public health agencies advise hunters to have their animal tested before consuming the meat.