Asthma diagnosis rates fall among children during COVID-19 pandemic
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The numbers of new cases of childhood asthma significantly fell during the COVID-19 pandemic in Japan, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
This decrease was consistent with trends in rhinovirus and respiratory syncytial virus (RSV) infections among children, Naomi Matsumoto, MD, PhD, assistant professor, department of epidemiology, faculty of medicine, dentistry and pharmaceutical sciences, Okayama University in Okayama, Japan, and colleagues wrote.
“In the COVID-19 pandemic, we hypothesized that not only the SARS-CoV-2 infection itself but also the social context of the pandemic and the accompanying behavioral changes may have had a significant impact on the physical and mental health of children,” Matsumoto told Healio.
“The worldwide reports of a dramatic decrease in viral infections following the COVID-19 pandemic could provide clues to measuring the impact of respiratory viral infections on the development of pediatric disease,” Matsumoto continued.
The researchers examined data from the nationwide RWD database, which includes approximately 24.4 million electronic medical records from 225 medical institutions across Japan. Their search revealed 29,845 asthma diagnoses and 17,803 atopic dermatitis diagnoses among children aged 15 years and younger between January 2017 and May 2021.
On March 2, 2020, the Japanese government asked local districts to close elementary and secondary schools.
“After the nationwide school closure due to the pandemic, the number of new diagnoses of childhood asthma dropped dramatically and remained at a low level for 15 months,” Matsumoto said. “This decline approximated that of RSV, rhinovirus, etc, and was more pronounced than the decline in atopic dermatitis, which is less commonly associated with viral infections.”
Specifically, during the pre-pandemic period of January 2017 through February 2020, the researchers found a mean of 668.74 (standard deviation [SD], 133.6) new cases of asthma each month across all age groups. In the pandemic period, from March 2020 through May 2021, that number fell to 295.53 (SD, 84.87).
These data equated to a 59% decrease, or 0.41 (95% CI, 0.34-0.5) change in level, which the researchers called “particularly pronounced.”
Children aged 0 to 2 years had the largest decrease, from a mean of 253.7 (SD, 78.4) diagnoses each month before the pandemic to 98.5 (SD, 37.2) during the pandemic, for a 0.28 (95% CI, 0.2-0.38) level change.
Also, the researchers examined the monthly numbers of new AD diagnosis during the pre-pandemic and pandemic periods as a control.
Across all age groups, there was a mean of 353.38 (SD, 42.47) new diagnoses of AD each month before the pandemic and 287.21 (SD, 24.47) during the pandemic for a 20% decrease and 0.8 (95% CI, 0.71-0.9) change in level.
Further, the researchers said that these figures suggested seasonality in new asthma and AD diagnoses, particularly among patients diagnosed with asthma, with marked increases of new diagnoses around October of each year. However, the researchers said, this peak range associated with seasonality was smaller among younger age groups with a higher risk for respiratory viral infections.
Overall, the researchers said, new diagnoses of childhood asthma significantly declined once the COVID-19 pandemic began and they still had not recovered after 15 months, which is a trend that is reasonably consistent with decreases in RSV and rhinovirus diagnoses during the pandemic.
“The nationwide school closures and the subsequent change in people’s hygiene behavior led to a marked decrease in the number of new diagnoses of childhood asthma,” Matsumoto said. “This may be due to decreased respiratory viral infections such as RSV and rhinovirus infections.”
Considering the slight decrease in new cases of AD by comparison, the researchers concluded, there appears to be an association between new onset of asthma among children and respiratory viral infections.
“Respiratory viral infections may significantly contribute to the development of new cases of childhood asthma. Recommendations for hygiene behaviors for high-risk children may be required,” Matsumoto said. “Whether a reduction in respiratory viral infections in susceptible early childhood prevents the onset of asthma later in life requires further, longer-term follow-up.”
For more information:
Naomi Matsumoto, MD, PhD, can be reached at naomim@okayama-u.ac.jp.
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Angela Duff Hogan, MD, FAAAAI, FACAAI, FAAP
This study is an interesting analysis of new cases of asthma in children from an extensive nationwide electronic medical record database (24.4 million/225 medical institutions) in Japan. EMR data were included from 45 facilities with “complete data” from January 2017 to May 2021. That database selected 29,845 new diagnoses of asthma in children aged 15 years and younger for review.
The researchers also chose newly diagnosed atopic dermatitis in the same sample as a control group based on presumed less susceptibility to viral infections. Next, they compared the incidence of asthma during the pre-COVID time frame of January 2017 to February 2020 to the COVID-19 pandemic period of March 2020 to May 2021. The number of newly diagnosed asthma cases decreased by 59% during the COVID-19 pandemic.
Clinically in the U.S., there were significantly fewer emergency room visits for asthma exacerbations noted during the COVID-19 pandemic. There were concerns initially that the SARS-CoV-2 virus would cause more severe and frequent asthma exacerbations in asthmatics. However, in allergic children, the frequency and severity of SARS-CoV-2 infections were much less in part due to the ACE2 receptor (the entry point for SARS-CoV-2) having decreased availability because of reduced expression in airway epithelium and other factors.
During the 2022 asthma season, there has been a significant increase in the severity and number of asthma exacerbations. Multiple children have been infected with two or three viruses concurrently. Some of this surge may be because they have not previously seen these viruses due to a lack of exposure and the use of masks and hand sanitizer.
Early-life viral infection can have profound effects on the developing lung and immune systems, both important in asthma development. The timing of viral infections on a potentially susceptible immune system, as well as which virus (ie, rhinovirus A, B or C; respiratory syncytial virus; or metapneumovirus) can impact the development of wheezing/asthma episodes in young children.
It has also been demonstrated that the host’s baseline microbiome present during the viral infection can also affect the subsequent development of wheezing/asthma. During the COVID-19 pandemic, young children had fewer courses of antibiotics due to less exposure to pathogens. Antibiotics can alter the microbiome, increasing susceptibility to wheezing episodes with certain viruses.
A 59% reduction in new asthma cases is impressive and calls into question at a population level if we could find new ways to reduce viral exposures to young infants. However, these early interventions could reduce early asthma onset.
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