ERS Roundup: Air Filtration Succeeds in Reducing Infections

Research presented at the annual European Respiratory Society (ERS) congress in Vienna included studies on air filtration for reducing infections in day care, betamethasone for kids hospitalized with community-acquired pneumonia (CAP), and the association between asthma in women and the use of fertility treatment.

Cleaner Air Cuts Monthly Infection Rate at Day Care

Air purification at day care centers in Finland reduced infections among children by 18%, a researcher reported.

In a small 2-year study involving about 50 kids, monthly infections per child dropped from 0.95 at baseline to 0.78 after implementation of the intervention (P=0.028), reported Ville Vartiainen, MD, PhD, of Helsinki University Hospital.

“We did nothing on the other transmission routes,” Vartiainen stressed during his late-breaking presentation.

“Children were putting their fingers to their noses and putting their fingers in each others’ mouths, and we didn’t do anything about that,” he continued. “It has to mean that airborne transmission is important.”

The intervention was also associated with a non-significant 16% decrease in parental absence from work (P=0.46), a secondary endpoint.

A growing body of evidence suggests that aerosols are a significant contributor to the transmission of common infections, said Vartiainen, and the goal of the study was to determine the degree to which airborne transmission played a part in the day care setting, along with the effectiveness of air purification.

The crossover study included four day care centers in Helsinki, with data collected in 2022-2023 and 2023-2024 during the respiratory virus seasons (November to April). All 262 children attending the day cares and their guardians were invited to participate; 88 parents or guardians consented initially, but after withdrawals 51 were included in the final analysis.

To increase pathogen-free air, investigators used an infection-risk model to identify the hotspots where the intervention would have the most impact — places where children spent a lot of time and where lots of people congregated. The intervention was first conducted at two day cares and then the equipment was transported to the other two centers. Analyses adjusted for age, sex, time period, and the sequence of crossover.

Added to the typical ventilation at the centers, air purification led to a 2.1- to 2.9-fold increase in clean air. For example, one center’s volumetric air flow increased from 14.5 to 42.3 liters per second per person. The intervention also decreased particulate matter in the air, said Vartiainen.

“We need building engineers to design more safe public environments,” said Vartiainen. “We as medical doctors cannot design buildings.”

Steroid No Help for Children Hospitalized With CAP

Adjunct treatment with betamethasone did not improve outcomes among kids admitted to the hospital for CAP, a placebo-controlled randomized trial showed.

In the so-called KIDS-STEP study, median time to clinical stability was 45.7 hours with the steroid atop usual care, as compared with 41.2 hours with placebo (P=0.68), reported Julia Anna Bielicki, MD, PhD, of St. George’s University of London and University Children’s Hospital of Basel in Switzerland.

Adjunct oral betamethasone met criteria for noninferiority when it came to the co-primary outcome of CAP rehospitalization (7.2% vs 5.4% with placebo), but “based on a lack of effectiveness” the trial findings do not support its use in this setting, said Bielicki.

She noted that some trials have demonstrated a mortality benefit with adjunct corticosteroids in adults with CAP in intensive care. And some data support a role for reducing time to clinical stability in milder cases, but data from trials in the pediatric setting have been inconclusive.

From September 2018 through February 2024, the KIDS-STEP trial enrolled 509 children hospitalized at a dozen sites in Switzerland and Germany. Children needed to be at least 6 months old and no older than 13 years, have a clinical diagnosis of CAP (irrespective of suspected or known etiology), and could not have bronchiolitis or an obstructive airway disease.

Median age of the participants was about 33-34 months, and a majority were boys. Around 90% had been vaccinated according to their national schedule, roughly 10% had atopy, and 17% lived in households with smokers. At admission, just under half were receiving oxygen and 26-30% had received antibiotics.

A more rapid resolution of abnormal heart rate was observed with the steroid, but there was no evidence of more rapid resolution of abnormal breathing or differences in time to discharge between groups.

More Fertility Care Use Among Women With Asthma

In a nationwide cohort study using Danish registries, asthma was associated with an increased use of fertility care services.

Among more than 750,000 women, a higher proportion of those with asthma received fertility treatment when compared with women without the respiratory condition (5.6% vs 5.0%, respectively). The difference represented a 12% greater risk in adjusted models (HR 1.12, 95% CI 1.08-1.15), according to Anne Vejen Hansen, MD, of Copenhagen University Hospital in Denmark.

The association correlated both with asthma severity and exacerbation burden, she said. Increasing asthma severity on the Global Initiative for Asthma (GINA) guidelines — determined in the study by fulfilled prescriptions of more intensive medications — was associated with up to a 62% greater risk of receiving fertility care compared with the non-asthma controls:

• GINA step 3: HR 1.38 (95% CI 1.23-1.54)
• GINA steps 4-5: HR 1.62 (95% CI 1.43-1.83)

And a greater number of documented exacerbations — either a high-dose course of oral corticosteroids or a hospitalization for asthma — was linked with up to a 38% higher risk of needing fertility care:

• Two exacerbations: HR 1.23 (95% CI 1.06-1.43)
• Three or more exacerbations: HR 1.38 (95% CI 1.19-1.60)

“However, it is very important to say that asthma does not seem to affect the number of live births in women with asthma,” said Vejen Hansen.

For the study, the researchers used several Danish registries to include all women born from 1976 to 1999 who were alive and living in Denmark at age 18. The 769,880 women were followed through Dec. 31, 2017. Asthma was defined as two prescriptions of an asthma medication fulfilled within a period of 12 months after the age of 6 years.

In total, 114,791 women met the criteria for asthma and 655,089 did not. Across the two groups, 6,403 and 32,840, respectively, received fertility care at some point during follow-up. That 15% prevalence of asthma is higher than what would normally be expected in Denmark, said Vejen Hansen. This was likely due to the fact that for the study, women remained permanently in the asthma group (i.e., some women may have started treatment but later found out they didn’t have asthma and some may have gone into remission).

Data from the abstract of the presentation showed that women with asthma had a higher rate of fetal loss as well (17% vs 15.7% in the controls), but that live birth rates were identical between groups (77%).

Analyses adjusted for confounders such as age, calendar year, and education, but a limitation was that the database did not capture potential confounders like body mass index and smoking history, which are known to affect fertility, said Vejen Hansen.

Researchers also looked at excessive use of short-acting beta 2-agonists, defined as more than 600 doses in a particular year, but found no association with receipt of fertility care.

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