Suppressed pediatric asthma hospitalizations during the COVID-19 pandemic in Japan, from a national survey.

BACKGROUND: Acute asthma exacerbation in children is often caused by respiratory infections. In this study, a coordinated national surveillance system for acute asthma hospitalizations and causative respiratory infections was established. We herein report recent trends in pediatric acute asthma hospitalizations since the COVID-19 pandemic in Japan. METHODS: Thirty-three sentinel hospitals in Japan registered all of their hospitalized pediatric asthma patients and their causal pathogens. The changes in acute asthma hospitalization in children before and after the onset of the COVID-19 pandemic and whether or not COVID-19 caused acute asthma exacerbation were investigated. RESULTS: From fiscal years 2010-2019, the median number of acute asthma hospitalizations per year was 3524 (2462-4570), but in fiscal years 2020, 2021, and 2022, the numbers were 820, 1,001, and 1,026, respectively (the fiscal year in Japan is April to March). This decrease was observed in all age groups with the exception of the 3- to 6-year group. SARS-CoV-2 was evaluated in 2094 patients from fiscal years 2020-2022, but the first positive case was not detected until February 2022. Since then, only 36 of them have been identified with SARS-CoV-2, none of which required mechanical ventilation. Influenza, RS virus, and human metapneumovirus infections also decreased in FY 2020. In contrast, 24% of patients had not been receiving long-term control medications before admission despite the severity of bronchial asthma. CONCLUSION: SARS-CoV-2 was hardly detected in children with acute asthma hospitalization during the COVID-19 pandemic. This result indicated that SARS-CoV-2 did not induce acute asthma exacerbation in children. Rather, infection control measures implemented against the pandemic may have consequently reduced other respiratory virus infections and thus acute asthma hospitalizations during this period. However, the fact that many hospitalized patients have not been receiving appropriate long-term control medications is a major problem that should be addressed.

Molecular Epidemiology of Respiratory Syncytial Virus during 2019-2022 and Surviving Genotypes after the COVID-19 Pandemic in Japan.

To evaluate the changes in respiratory syncytial virus (RSV) collected between 2019 and 2022, we analyzed RSV-A and RSV-B strains from various prefectures in Japan before and after the COVID-19 pandemic. RT-PCR-positive samples collected from children with rapid test positivity at outpatient clinics in 11 prefectures in Japan were sequenced for the ectodomain of the G gene to determine the genotype. Time-aware phylogeographic analyses were performed using the second hypervariable region (HVR) of the G gene from 2012 to 2022. Of 967 samples, 739 (76.4%) were found to be RSV-positive using RT-PCR. RSV peaked in September 2019 but was not detected in 2020, except in Okinawa. Nationwide epidemics occurred with peaks in July 2021 and 2022. The genotype remained the same, ON1 for RSV-A and BA9 for RSV-B during 2019-2022. Phylogeographic analysis of HVR revealed that at least seven clusters of RSV-A had circulated previously but decreased to two clusters after the pandemic, whereas RSV-B had a single monophyletic cluster over the 10 years. Both RSV-A and RSV-B were transferred from Okinawa into other prefectures after the pandemic. The RSV epidemic was suppressed due to pandemic restrictions; however, pre-pandemic genotypes spread nationwide after the pandemic.

Factors Contributing to Symptom Duration and Viral Reduction in Outpatient Children With Respiratory Syncytial Virus Infection.

BACKGROUND: We investigated the association between age, duration of clinical symptoms and viral shedding in outpatient children infected with respiratory syncytial virus (RSV) in Japan. METHODS: Outpatients younger than 2 years of age, with suspected RSV infection between 2014 and 2018, were enrolled in the study. Following informed consent, nasal samples were collected at first and second clinic visits (with 0-9 days gap). RSV-A or -B infection and viral load were determined by real-time polymerase chain reaction. Clinical symptoms were recorded at first clinic visit, and fever and symptoms were recorded at home for up to 8 days. Association between clinical symptoms and patient characteristics, such as age, sex and birth weight, were analyzed using ordered logistic regression analysis. The association between viral reduction and estimated shedding period was examined using linear regression analysis. RESULTS: Among the 205 cases enrolled in the study, no difference was found in patient characteristics between RSV-A and -B infection. Duration of fever was prolonged with increased age. Duration of rhinorrhea and cough was shorter in females than in males and in groups with birth weight ≥3 kg than in those with <2.5 kg. Daily viral reduction increased and estimated viral elimination period decreased with age. CONCLUSIONS: Fever duration was found to increase while viral shedding decreased with patient age.

Respiratory Syncytial Virus Surveillance System in Japan: Assessment of Recent Trends, 2008-2015.

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract illness in infants and young children. In Japan, surveillance for RSV infection started in 2003 based on approximately 3,000 pediatric sentinel sites. In recent years, RSV notifications have increased, but the interpretation of trends has been challenging due to a suspected increase in testing frequency and the expansion of the insurance coverage for RSV testing to include certain outpatients in late 2011. Therefore, we evaluated RSV surveillance data during 2008-2015, considering the number of sites that reported at least one RSV case during a surveillance year and restricting to sites that had continuous reporting status since 2008. While annual RSV notifications had increased, the number of sites reporting also increased. And the same magnitude of increase was not observed when the number of cases reported was restricted to the 1,372 sites that had continuous reporting status since 2008. Additionally, in the year following the insurance expansion, RSV notifications increased more remarkably for clinics than for hospitals. These results suggested that some of the recent increases in notifications might be due to an increase in testing frequency.

[Construction and operation of Internet Search Engine specialized in information on asthma. A Search Engine-based investigation to identify asthma-related information needed by Internet users].

To support asthmatic patients in collecting information through the Internet, we have constructed and operated a search engine specialized in asthma-related information making use of the search engine software available free of charge and other programs. A questionnaire was attached to the bottom of the Web page presenting the search results, asking the users to respond to several questions. During the three-year period since its start of operation on June 1, 2000, there was 66689 visits to this site and 786 responses to the questionnaire were collected. Of all respondents, 19.3% were medical professionals, 63.7% were patients or their family members, and 11.3% belonged to the other categories (5.3% did not specify their position). In each of these three user groups, only about half of the users were able to find a route to the information they needed. This seems to reflect the absence of adequate asthma-related information sources on the Internet in Japanese language. However, more than 70% of all users in each group answered that this search engine site was useful.