Receiving an influenza vaccine with or without a co-administered COVID-19 vaccine was associated with a small and temporary—but meaningful—change in the menstrual cycles of regularly menstruating women, according to a study published yesterday in JAMA Network Open.

The study was based on data collected from an English-language digital birth control app used globally. Data from April 25, 2023, to February 27, 2024 (4 to 5 menstrual cycles per individual) were collected from 1,501 participants. All participants were ages 18 to 45 years old, did not use hormonal contraception, and had an average cycle length of 24 to 38 days in 3 consecutive cycles before receipt of vaccines.

Of the 1,501 participants, 791 were vaccinated for influenza only and 710 were concurrently vaccinated for influenza and COVID-19. Overall cycle length increased by less than one day if the influenza vaccine was administered in the follicular (pre-ovulation) phase.

Cycle length increased by 1 day 

Women vaccinated for influenza alone experienced an adjusted mean increase of 0.40 (95% confidence interval [CI], 0.08 to 0.72) days, while those vaccinated concurrently for influenza and COVID-19 experienced a mean increase of 0.49 (95% CI, 0.16 to 0.83) days. 

Only 37 individuals (4.7%) experienced a change in cycle length of at least 8 days with influenza vaccine only, and 42 (5.9%) with concurrent receipt of both vaccines.

In the cycle following vaccination, lengths returned to normal. 

While small changes in menstrual health may not seem meaningful to many clinicians and scientists, any perceived impact in a routine bodily function linked to fertility can cause alarm and contribute to vaccine hesitancy,” the authors wrote. Referring to similar studies on the COVID-19 vaccine, the authors said public perception of menstrual cycle changes add to mistrust of vaccines, so studies showing these changes transparently can help assure vaccine recipients. 

Our findings can confirm that concurrent receipt of influenza and COVID-19 vaccines does not appear to be associated with large menstrual cycle changes in most people.

“Our findings can confirm that concurrent receipt of influenza and COVID-19 vaccines does not appear to be associated with large menstrual cycle changes in most people,” they concluded. 

A personalized inhaled bacteriophage therapy showed promising results in a small study of cystic fibrosis (CF) patients with drug-resistant pulmonary infections, researchers reported yesterday in Nature Medicine.

The study, led by researchers at Yale University's Center for Phage Biology and Therapy, enrolled nine adults with CF who were selected for treatment on a compassionate use basis because they had multidrug- and pan–drug-resistant Pseudomonas aeruginosa infections that were no longer responding to standard antibiotic therapies. P aeruginosa frequently colonizes the lungs of CF patients and is the most common cause of CF exacerbations.

The patients were treated for 7 to 10 days with a cocktail of environmentally sourced, personalized phages with activity against P aeruginosa that was delivered through a nebulizer. The hypothesis was that the therapy might select for evolved resistance to phages in the patients' P aeruginosa isolates, but there would be an evolutionary tradeoff—either decreased virulence or reduced resistance to antibiotics.

"A phage therapy strategy that leverages such a trade-off could result in improved clinical outcomes by decreasing bacterial burden and by selecting for surviving bacterial mutants that are less resistant to antibiotics or less virulent," the study authors wrote.

Improved lung function 

Five to 18 days after therapy, analysis of sputum samples collected before and after treatment showed a reduction in colony forming units (CFUs) of P aeruginosa in all patients. Furthermore, while the study authors note that reduced CFU of sputum bacteria doesn't always translate to clinical improvements in CF patients, they found that each participant had improved lung function after the inhaled phage therapy.

Analysis of post-therapy P aeruginosa isolates from the nine patients found that the cocktail had exerted selection for phage resistance, but some of the isolates were more susceptible to antibiotics, and others were less virulent.

The authors say the findings suggest inhaled phage therapy has the potential to translate into promising clinical applications.

"Further studies of this new therapeutic are currently underway in clinical trials, and our personalized phage therapy approach will similarly require larger clinical trials," they wrote.

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today reported 15 more H5N1 avian flu detections in Idaho dairy cattle, which over the past several weeks have become the nation's epicenter of virus activity.

The pace of detections picked up in March, and the state has now reported 86 confirmations in dairy cows, the nation's second most behind California. The latest detections push the national total since March 2024 to 1,047 from 17 states.

The Idaho State Department of Agriculture said 59 herds in four counties are in quarantine. Most are in Gooding (34 herds) and Jerome (17) counties, but there are also a few in Twin Falls (7) and Cassia (1) counties. All are located near each other in the far south-central part of the state.

Idaho is the nation's third-largest milk producer and has more than 350 family-owned dairy farms, according to the agriculture department's dairy bureau. 

Mammal detections, vaccine deal

In other H5N1 developments, APHIS reported 10 more H5H1 detections in mammals besides livestock from six different states. Most positive samples were collected in late March and into April. One case involved a domestic cat in Weld County, Colorado. The others were wildlife, including skunks from California and Colorado, a raccoon from New York, foxes from Virginia and Texas, and a weasel from Washington state.

Elsewhere, the European Commission this week announced a procurement commitment with CSL Seqirus that would allow 17 countries the opportunity to buy up to 27,403,200 million doses of pandemic flu vaccine as part of pandemic flu preparedness. The agreement would secure the vaccine if the World Health Organization or European Union declares a flu pandemic.

Scientists have discovered that the same device used to measure C-reactive protein (CRP) in blood to diagnose bacterial meningitis is also sensitive enough to measure it in cerebrospinal fluid (CSF), which can speed accurate diagnosis and treatment of the life-threatening illness, according to a study published yesterday in The Lancet Regional Health Europe.

Researchers from the University of Amsterdam in the Netherlands and their colleagues validated the test in two cohorts of patients who had confirmed or suspected central nervous system (CNS) infections. 

The team measured CRP in the CSF of 103 adults from Denmark, including 34 (33%) with bacterial meningitis, and 77 Dutch children, 17 of whom (22%) had bacterial meningitis. The investigators then implemented and tested it in clinical practice in 80 patients, of whom 15 (19%) were diagnosed as having bacterial meningitis, from June to November 2024.

Ready for clinical use, authors say

In the adults, the area under the curve (AUC) was 0.92, indicating an excellent ability to diagnose bacterial meningitis. With a predetermined cutoff of 0.3 milligrams per liter (mg/L), sensitivity was 85%, and specificity was 96%.