Evolutionary analysis of human respiratory syncytial virus collected in Myanmar between 2015 and 2018

Molecular epidemiological surveillance of respiratory syncytial virus infection in Myanmar from 2019 to 2023

To evaluate genetic changes in respiratory syncytial virus (RSV) between 2019 and 2023, we analyzed RSV strains from Myanmar before and after the COVID- 19 pandemic. Real-time polymerase chain reaction (RT-PCR) positive samples from children presenting with acute respiratory infections at outpatient clinics in Yangon were sequenced to determine the genotype. Phylogenetic and molecular evolutionary analyses were conducted using the Bayesian Markov Chain Monte Carlo method to construct the time-scale Maximum Clade Credibility tree. Of 1127 samples, 104 (9.2%) RSV-A and 233 (20.7%) RSV-B were positive by RT-PCR. There was an absence of a notable epidemic in 2020, a temporal shift with a surge of RSV-A in the 2021 outbreak, a lack of expected cases in 2022 and a substantial resurgence of RSV-B in 2023. The genotype of RSV-A was mainly A.D.3 lineage through the study period, while RSV-B were B.D.4.1.1 and B.D.E.1. RSV-A showed that the same lineage persisted within Myanmar throughout the pandemic, leading to a large outbreak post-COVID. In contrast, RSV-B strains appear to have temporarily disappeared during the pandemic, but subsequently, globally circulating strains likely entered Myanmar, resulting in a major outbreak in 2023. The estimated evolutionary rate at the G-ectodomain for RSV-A was 7.76 × 10⁻³ and RSV-B was 5.67 × 10⁻³ substitutions/site/year. Strengthening genomic surveillance will likely support comparisons of circulating strains with those in other countries and facilitate the introduction of vaccines and other interventions.

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.

Detection of parechovirus-A in hospitalized children with acute lower respiratory infection in Myanmar, 2017-2018

Parechovirus-A (PeV-A) causes emerging infection in children, and clinical presentation depends on genotype. The virus has been investigated mainly in developed countries; however, data from developing countries, especially in Asia, are sparse. This study investigated whether PeV-A circulated in children in Myanmar. This retrospective study evaluated PeV-A in nasopharyngeal samples from children aged 1 month to 12 years who were hospitalized with acute lower respiratory infection at Yankin Children Hospital, Yangon, Myanmar, during the period from May 2017 to April 2019. Real-time polymerase chain reaction (PCR) was used to detect PeV-A, and PCR-positive samples were used for genotyping and phylogenetic analysis. In total, 11/570 (1.9%) of samples were positive for PeV-A; 7 were successfully genotyped by sequencing the VP3/VP1 region, as follows: PeV-A1 (n = 4), PeV-A5 (n = 1), PeV-A6 (n = 1), and PeV-A14 (n = 1). Median age was 10.0 months (interquartile range 4.0-12.0 months), and other respiratory viruses were detected in all cases. Phylogenetic analysis showed that all detected PeV-A1 strains were in clade 1 A, which was a minor clade worldwide. Four PeV-A genotypes were detected in Myanmar. The clinical impact of PeV-A in children should be evaluated in future studies.