COVID-19 Pandemic-Related Reductions in Pediatric Asthma Exacerbations Corresponded with an Overall Decrease in Respiratory Viral Infections.

BACKGROUND: Respiratory viruses, air pollutants, and aeroallergens are all implicated in worsening pediatric asthma symptoms, but their relative contributions to asthma exacerbations are poorly understood. A significant decrease in asthma exacerbations has been observed during the coronavirus disease 2019 pandemic, providing a unique opportunity to study how major asthma triggers correlate with asthma activity. OBJECTIVE: To determine whether changes in respiratory viruses, air pollutants, and/or aeroallergens during the coronavirus disease 2019 pandemic were concomitant with decreased asthma exacerbations. METHODS: Health care utilization and respiratory viral testing data between January 1, 2015, and December 31, 2020, were extracted from the Children's Hospital of Philadelphia Care Network's electronic health record. Air pollution and allergen data were extracted from US Environmental Protection Agency public databases and a National Allergy Bureau-certified station, respectively. Pandemic data (2020) were compared with historical data. RESULTS: Recovery of in-person asthma encounters during phased reopening (June 6 to November 15, 2020) was uneven: primary care well and specialty encounters reached 94% and 74% of prepandemic levels, respectively, whereas primary care sick and hospital encounters reached 21% and 40% of prepandemic levels, respectively. During the pandemic, influenza A and influenza B decreased to negligible frequency when compared with prepandemic cases, whereas respiratory syncytial virus and rhinovirus infections decreased to low (though nonnegligible) prepandemic levels, as well. No changes in air pollution or aeroallergen levels relative to historical observations were noted. CONCLUSIONS: Our results suggest that viral respiratory infections are a primary driver of pediatric asthma exacerbations. These findings have broad relevance to both clinical practice and the development of health policies aimed at reducing asthma morbidity.

Pediatric selective IgM immunodeficiency.

OBJECTIVE: Limited information exists on features of pediatric Selective IgM immunodeficiency (SIgMID). Previously published pediatric cases and 2 new cases are reviewed. METHODS: English literature from PubMed and references from relevant articles were reviewed. Previously reported cases and 2 new cases from an allergy/immunology practice were analyzed. RESULTS: Forty-nine reported cases of SIgMID presented with respiratory infections (77.6%), gastrointestinal disease (16.3%), skin disease (12.2%), and meningitis (8.2%). Mean serum IgM level was 16.5+/-13.8 mg/dL. Two patients were identified with SIgMID among 6300 active pediatric patients (0.03%) presenting with asthma, vasomotor rhinitis, and recurrent respiratory infections. In the 51 cases reported, none developed lymphoproliferative disease nor evolved into panhypogammaglobulinemia; four fatalities were reported. CONCLUSIONS: The prevalence of SIgMID in our pediatric population was 0.03%. In general, respiratory infections are the common comorbid conditions. Death and autoimmune disease are uncommon complications of pediatric SIgMID.

Selective IgM immunodeficiency: retrospective analysis of 36 adult patients with review of the literature.

OBJECTIVE: To review and compare previously reported cases of selective IgM immunodeficiency (SIgMID) with the largest adult cohort obtained from a retrospective analysis of an allergy and immunology practice. DATA SOURCES: Publications were selected from the English-only PubMed database (1966-2005) using the following keywords: IgM immunodeficiency alone and in combination with celiac disease, autoimmune disease, malignancy, and infection. Bibliographic references of relevant articles were used. STUDY SELECTION: Reported adult SIgMID cases were reviewed and included in a comparative database against our cohort. RESULTS: Previously described patients with SIgMID include 155 adults and 157 patients of unspecified age. Thirty-six adult patients were identified with SIgMID from a database of 13,700 active adult patients (0.26%, 1:385). The mean +/- SD serum IgM level was 29.74 +/- 8.68 mg/dL (1 SD). The mean +/- SD age at the time of diagnosis of SIgMID was 55 +/- 13.5 years. Frequency of presenting symptoms included the following: recurrent upper respiratory tract infections, 77%; asthma, 47%; allergic rhinitis, 36%; vasomotor rhinitis, 19%; angioedema, 14%; and anaphylaxis, 11%. Serologically, 13% of patients had positive antinuclear antibodies (ANAs), 5% had serologic evidence of celiac disease, and nearly all had non-AB blood type. Patients also had low levels of IgM isohemagglutinins. No patients developed lymphoproliferative disease or panhypogammaglobulinemia, and none died of life-threatening infections, malignancy, or fulminant autoimmune-mediated diseases during a mean follow-up period of 3.7 years. CONCLUSIONS: The prevalence of SIgMID in our adult population was 0.26% and may be more common than previously thought. Non-life-threatening respiratory disorders were common comorbid conditions.

Forced expiratory time and bronchial hyperresponsiveness to methacholine.

Pulmonary junction tests (PFTs) are normally performed prior to methacholine inhalation challenges (MICs). In contrast to normal baseline spirometry (FEV1, FEF25%-27%, FVC), we have observed patients with positive MICs having shortened forced expiratory times (FET100%) in the baseline pre-MIC PFT. We prospectively evaluated the correlation of abnormalities in baseline pre-MIC FET100% in patients who have positive vs. negative MICs. Prospective analysis of baseline pre- MIC FET100%, and MIC results in suspected asthmatics with normal lung exams, spirometry and chest x-rays. Using a PC20 FEV1 of < or =8mg/ml methacholine there were 115 positive and 69 negative MICs. The mean (+/-1 SD) FET100% in the positive MIC group was 3.57+/-1.68 sec vs. 4.73+/-1.60 sec in the negative group. The difference in these means was statistically significant (p <0.0001). There was a statistically significant difference in the incidence of FET100% <4sec in the positive (55.65%) vs. the negative (30.43%) MIC group, p<0.001. There was also a statistically significant difference in the incidence of positive MIC in FET100% <4sec (75.29%) vs. FET100%, > or =4sec (51.52%), p< 0.001. Our results suggest that in our highly selected, well-characterized population, FET100.% <6sec is common and FET100% <4 sec correlates with an increased likelihood of having a positive MIC.