Impact of the Omicron strain on febrile convulsions in children: A single-center observational study (preprint)

<Purpose> The emergence of the Omicron strain of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the end of December 2021 has drastically increased the number of infected children in Japan, along with the number of children with febrile convulsions. However, impact of the Omicron strain on the febrile convulsions in children is not clear.<Methods> We compared the frequency of SARS-CoV-2 infection in children hospitalized with febrile convulsions with the frequency of SARS-CoV-2 infection in children with fever and respiratory symptoms without convulsions.<Results> In 2021 and 2022, 49 and 58 children, respectively, required emergency hospitalization for febrile convulsions (FC group), in which 24 and 38 children underwent a Filmarray respiratory panel ® test (FA test) and quantitative antigen test for SARS-CoV-2, respectively. In 2022, only six patients tested positive for SARS-CoV-2 (10.3%, 6/58). As a reference group, 655 children aged < 10 years who underwent the FA test for fever and respiratory symptoms during the same period were investigated, and 4 (1.8%, 4/223) and 42 (9.7%, 42/432) tested positive for SARS-CoV-2 in 2021 and 2022, respectively. Rhinovirus/enterovirus (RV/EV) was the most frequently detected virus, followed by respiratory syncytial virus (RSV) and parainfluenza virus 3 (PI3); no significant difference in the trend of detected viruses was observed between the two groups.<Conclusions> The frequency of febrile convulsions associated with SARS-CoV-2 infection of the Omicron strain in children may be similar to that of other common respiratory viruses.

Selective change in the bacterial flora in respiratory sputum from elderly patients during the SARS-CoV-2 pandemic (preprint)

The pandemic of SARS-CoV-2 has affected the social lifestyle and consequently the prevalence of infections, such as seasonal influenza. It has been reported that invasive pneumococcal infection is markedly decreased worldwide. <Method> We retrospectively investigated the bacterial flora of 23,052 respiratory sputum samples obtained at our hospital from April 2015 to March 2022. The average patient age was 71.8 years old with a standard deviation of 16.0 years old. There was no significant difference in the age of the patients or the female-to-male ratio between each year. The detection ratio of bacteria was analyzed in accordance with sputum quality based on the Geckler classification. <Results> The detection ratio of community-acquired pneumonia pathogens such as Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae increased in parallel with the quality of the sputum, while that of hospital-acquired pneumonia pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus was not significantly affected by the quality of the sputum. The former detection ratio decreased significantly since April 2020 by 60–80% for two years in a row, while that of the latter did not change between each year. <Conclusions> The pandemic of SARS-CoV-2 reduced the detection ratio of community-acquired pathogens such as Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae but not hospital-acquired pneumonia pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus in the respiratory sputum from elderly patients.

Investigation of respiratory viruses by multiplex PCR method in the community suggested reciprocal virus transmission between children and adults (preprint)

The observational study of respiratory virus infection for children has already been reported, but there are few reports that examined both children and adults simultaneously in the community. We performed a multiplex PCR (polymerase-chain reaction) assay of respiratory viruses by using FilmArray respiratory panel version 2.1 for 248 children (under 15 years old) and 5,354 adults (15 years old or older) who were admitted or visited our hospital with respiratory symptoms and/or fever from December 2020 to November 2021. During this period, a seasonal outbreak of respiratory syncytial virus (RSV) and parainfluenza virus 3 (PI3) was found as well as a pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In adults, viruses were detected in 6.8% (364/5,354), and SARS-CoV-2 accounted for 228 cases. Only two cases presented multiple viruses. In children, viruses were detected in 64.9% (161/248), while 75.4% (135/179) were under 5 years old. Multiple viruses were detected in 26 cases, all of which were under 5 years old. SARS-CoV-2 was positive in six children. RSV prevailed both in children and adults simultaneously, while the PI3 outbreak was found first in children, followed by adults three weeks later. Rhinovirus/enterovirus (RV/EV) was detected throughout the year with some fluctuation and was mostly found in children under 5 years old and in adults aged between 20s and 30s, which suggested reciprocal virus transmission between the children and the parents.

Utility of quantitative antigen assay for SARS-CoV-2 in the clinical situation Single center experience from Japan (preprint)

From December 26, 2020 to February 28, 2021, quantitative antigen test (Ag test) of SARS-CoV-2 was conducted by using a nasopharyngeal swab for 990 patients aged from 0 to 99 years old (average age; 63.1 +/-22.5 years old, male: 537, female: 463), who presented at least one of the following symptoms, such as fever, respiratory symptoms, and taste disorder. In 578 patients, Ag test and PCR test were conducted at the same time and these patients were analyzed. In 74 patients with Ag > = 1.0, 44 patients were PCR positive (positive ratio = 0.59). In 43 patients with Ag > = 10.0, 41 patients were PCR positive (positive ratio = 0.95), and all of 42 patients with Ag > = 100.0 were PCR positive. In 504 patients with Ag < 1.0, only five patients were PCR positive (positive ratio = 0.01). In 31 patients with 10 > Ag > = 1.0, three patients were PCR positive (positive ratio = 0.10). All eight patients presented a typical pneumonia, and five patients had a history of close contact with COVID-19 patients within 14 days. With an appropriate cut off value, Ag test is concluded to have enough sensitivity and specificity. Considering the advantage of handiness, rapidness, high-throughput and economy over PCR test, Ag test seems useful diagnostic method for COVID-19 in the pandemic situation.