Impact of COVID-19 on the Changing Patterns of Respiratory Syncytial Virus Infections

Respiratory syncytial virus: challenges in diagnosis and impact on the elderly: Recommendations from a multidisciplinary panel

Respiratory syncytial virus (RSV) is an important cause of respiratory illness. While most attention is paid to childhood infection, the RSV burden in adults ≥60 y should also be considered. In Brazil, this is generally underrecognized, where greater focus is toward other respiratory pathogens. This article presents insights from a multidisciplinary panel gathered to review epidemiologic data and current diagnostic approaches to RSV in Brazil (and their limitations) and develop communication strategies to improve knowledge and awareness. National surveillance data indicate a steady increase in cases of RSV-related severe acute respiratory illness (RSV-SARI) in those aged ≥60 y in recent years, with high fatality rates (>30%). Routine RSV testing in older individuals with respiratory symptoms is relatively low. Educational activities targeted toward health-care professionals and the general public are critical to raising awareness of the importance of RSV in older individuals, particularly as protective vaccines are now available.

The Impact of the COVID-19 Pandemic on Respiratory Syncytial Virus Infection in the Neonatal Period

OBJECTIVE

 Respiratory syncytial virus (RSV) is the most common viral respiratory infection in infants. This study aimed to establish the potential changes in the clinical course of RSV in the neonatal period with the onset of the coronavirus disease 2019(COVID-19) pandemic.

STUDY DESIGN

 During the observational study period, newborns diagnosed with community-acquired RSV infection and admitted to the neonatal intensive care unit (NICU) were evaluated. RSV-infected neonates before the COVID-19 pandemic were classified as Group 1, those during the strict isolation period as Group 2, and RSV-infected newborns after the removal of restrictions were classified as Group 3.

RESULTS

 A total of 208 community-acquired RSV-infected neonates were analyzed. The median age at admission to the NICU was 26 days, and the mean gestational week was 37.2 ± 2.7. The ratio of hospitalized babies with RSV infection to all hospitalized newborns rose after the pandemic significantly (1.9, 1.6, and 5.2%; p < 0.001). Following the pandemic, there was an increase in full-term, early-term, and late-preterm cases. Nevertheless, no change was observed in the number of preterm cases (p > 0.05). There was also a statistically significant increase in the need for intubation, noninvasive ventilation (NIV), supplemental oxygen, inhaled bronchodilator drugs, and length of hospital stay in Group 3 after the pandemic (p < 0.001). All these parameters related to more severe RSV infection when the precautions were removed, while there was a milder disease with restrictions during the pandemic in Group 2 (p < 0.001). However, none died due to RSV infection during the study because of timely supportive care.

CONCLUSION

 Following the COVID-19 pandemic, the frequency and severity of RSV infection in newborns have increased, and it can result in a serious clinical picture even in full-term babies with no comorbidities. Attention to strict contact precautions, particularly in newborns, who are a more vulnerable population after the pandemic, may play an important role in any future outbreak.

KEY POINTS

· The course of neonatal RSV infection has changed after the pandemic.. · A statistically significant increase was observed in the need of intubation in newborns with RSV.. · The strict precautions during the pandemic also helped to prevent the transmission of RSV..

Prevalence and Seasonal Patterns of 16 Common Viral Respiratory Pathogens during the COVID-19 Pandemic in Gauteng Province, South Africa, 2020-2021

Coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The COVID-19 pandemic resulted in widespread morbidity and mortality, but generally, the diagnosis of other respiratory viruses was limited. This study aimed to assess the prevalence of other respiratory viruses during the 2020/2021 pandemic among patients of all ages who accessed care at public healthcare facilities in Gauteng Province, South Africa. Laboratory diagnosis for respiratory viruses, with or without SARS-CoV-2, was conducted via multiplex real-time polymerase chain reactions using respiratory specimens. A total of 1776 patients were included from 1 April 2020 to 31 March 2021, of which 766 (43.1%) were positive for respiratory viruses other than SARS-CoV-2. RV (368/1776; 20.7%) was the most prevalent, followed by RSV (304/1776; 17.1%), AdV (112/1776; 6.3%) and EV (105/1776; 5.9%). hCoV-OC43 (39/1776; 2.2%) was the most prevalent common coronavirus. SARS-CoV-2 co-infections were detected in 4.8% (24/500) of patients. Only 27.1% (482/1776) of patients were admitted to high-care or intensive care units. A decrease in respiratory virus detections was observed, except for RSV, EV and hCoV-OC43. RSV prevalence increased in 2021, while influenza A/B viruses remained undetected.

Respiratory syncytial virus-associated pneumonia in primary care in Malawi

OBJECTIVE

To identify the prevalence of respiratory syncytial virus (RSV) in a cohort of children under 5 years of age with World Health Organization (WHO)-defined pneumonia and the factors associated with developing severe RSV-associated community-acquired pneumonia (CAP) in primary care in a single centre in Northern Malawi.

METHODS

The BIOmarkers TO diagnose PnEumonia (BIOTOPE) study was a prospective cohort study conducted from March to June 2016 that took place in a primary care centre in Northern Malawi. Data from this study was used to identify the characteristics of children under 5 years of age who presented with RSV and WHO-defined CAP. Means, standard deviations, medians and ranges were calculated for continuous variables. A univariate logistic regression was performed to examine the potential predictor variables.

RESULTS

Four hundred and ninety-four infants presented with CAP and were eligible for inclusion in the study; RSV infection was detected in 205 (41.6%) of the infants. Eight factors were associated with increased risk for RSV CAP in the univariate model: age, born at term, presenting for care in June, crowded living environment, not being exclusively breastfed, not having received zinc or vitamin A supplementation in the last six months. Infants with RSV were more likely to have an oxygen saturation ≤92% compared to infants with other causes of pneumonia and more likely to have severe pneumonia as defined by the WHO.

CONCLUSION

This study supports that RSV-associated CAP is linked to modifiable and non-modifiable risk factors; further research is indicated to determine which interventions would be most impactful. Developing and implementing an infant or maternal vaccine could be a cost-effective way to prevent RSV-associated CAP and mortality in developing nations. More research is needed to understand seasonal patterns of CAP and research over extended periods can offer valuable insights on host, environmental and pathogen-specific factors that contribute to RSV-associated CAP.

Intranasal antivirals against respiratory syncytial virus: the current therapeutic development landscape

INTRODUCTION

Respiratory syncytial virus (RSV) causes bronchiolitis and other respiratory issues in immunocompromised individuals, the elderly, and children. After six decades of research, we have only recently seen the approval of two RSV vaccines, Arexvy and Abrysvo. Direct-acting antivirals against RSV have been more difficult to develop with ribavirin and palivizumab giving very modest reductions in hospitalizations and no differences in mortality. Recently, nirsevimab was licensed and has proven to be much more effective when given prophylactically. These are delivered intravenously (IV) and intramuscularly (IM), but an intranasal (IN) antiviral has several advantages in terms of ease of use, lower resource need, and acting at the site of infection.

AREAS COVERED

In this paper, we review the available literature on the current pre-clinical research landscape of anti-RSV therapeutics tested for IN delivery.

EXPERT OPINION

As RSV is a respiratory virus that infects both the upper and lower respiratory tracts, efforts are focused on developing a therapeutic that can be delivered via the nasal route. The rationale is to directly target the replicating virus with an obvious respiratory tract tropism. This approach will not only pave the way for a nasal delivery approach aimed at reducing respiratory viral illness but also controlling aerosol virus transmission.

Risk Analysis of Respiratory Syncytial Virus Among Infants in the United States by Birth Month

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality among US infants. A child's calendar birth month determines their age at first exposure(s) to RSV. We estimated birth month-specific risk of medically attended (MA) RSV lower respiratory tract infection (LRTI) among infants during their first RSV season and first year of life (FYOL).

METHODS

We analyzed infants born in the USA between July 2016 and February 2020 using three insurance claims databases (two commercial, one Medicaid). We classified infants' first MA RSV LRTI episode by the highest level of care incurred (outpatient, emergency department, or inpatient), employing specific and sensitive diagnostic coding algorithms to define index RSV diagnoses. In our main analysis, we focused on infants' first RSV season. In our secondary analysis, we compared the risk of MA RSV LRTI during infants' first RSV season to that of their FYOL.

RESULTS

Infants born from May through September generally had the highest risk of first-season MA RSV LRTI-approximately 6-10% under the specific RSV index diagnosis definition and 16-26% under the sensitive. Infants born between October and December had the highest risk of RSV-related hospitalization during their first season. The proportion of MA RSV LRTI events classified as inpatient ranged from 9% to 54% (specific) and 5% to 33% (sensitive) across birth month and comorbidity group. Through the FYOL, the overall risk of MA RSV LRTI is comparable across birth months within each claims database (6-11% under the specific definition, 17-30% under the sensitive), with additional cases progressing to care at outpatient or ED settings.

CONCLUSIONS

Our data support recent national recommendations for the use of nirsevimab in the USA. For infants born at the tail end of an RSV season who do not receive nirsevimab, a dose administered prior to the onset of their second RSV season could reduce the incidence of outpatient- and ED-related events.

Long-term effects of non-pharmaceutical interventions on total disease burden in parsimonious epidemiological models

The recent global COVID-19 pandemic resulted in governments enacting non-pharmaceutical interventions (NPIs) targeted at reducing transmission of SARS-CoV-2. But the NPIs also affected the transmission of viruses causing non-target seasonal respiratory diseases, including influenza and respiratory syncytial virus (RSV). In many countries, the NPIs were found to reduce cases of such seasonal respiratory diseases, but there is also evidence that subsequent relaxation of NPIs led to outbreaks of these diseases that were larger than pre-pandemic ones, due to the accumulation of susceptible individuals prior to relaxation. Therefore, the net long-term effects of NPIs on the total disease burden of non-target diseases remain unclear. Knowledge of this is important for infectious disease management and maintenance of public health. In this study, we shed light on this issue for the simplified scenario of a set of NPIs that prevent or reduce transmission of a seasonal respiratory disease for about a year and are then removed, using mathematical analyses and numerical simulations of a suite of four epidemiological models with varying complexity and generality. The model parameters were estimated using empirical data pertaining to seasonal respiratory diseases and covered a wide range. Our results showed that NPIs reduced the total disease burden of a non-target seasonal respiratory disease in the long-term. Expressed as a percentage of population size, the reduction was greater for larger values of the basic reproduction number and the immunity loss rate, reflecting larger outbreaks and hence more infections averted by imposition of NPIs. Our study provides a foundation for exploring the effects of NPIs on total disease burden in more-complex scenarios.

SIR+ models: accounting for interaction-dependent disease susceptibility in the planning of public health interventions

Avoiding physical contact is regarded as one of the safest and most advisable strategies to follow to reduce pathogen spread. The flip side of this approach is that a lack of social interactions may negatively affect other dimensions of health, like induction of immunosuppressive anxiety and depression or preventing interactions of importance with a diversity of microbes, which may be necessary to train our immune system or to maintain its normal levels of activity. These may in turn negatively affect a population's susceptibility to infection and the incidence of severe disease. We suggest that future pandemic modelling may benefit from relying on 'SIR+ models': epidemiological models extended to account for the benefits of social interactions that affect immune resilience. We develop an SIR+ model and discuss which specific interventions may be more effective in balancing the trade-off between minimizing pathogen spread and maximizing other interaction-dependent health benefits. Our SIR+ model reflects the idea that health is not just the mere absence of disease, but rather a state of physical, mental and social well-being that can also be dependent on the same social connections that allow pathogen spread, and the modelling of public health interventions for future pandemics should account for this multidimensionality.

Global Seasonal Activities of Respiratory Syncytial Virus Before the Coronavirus Disease 2019 Pandemic: A Systematic Review

Varied seasonal patterns of respiratory syncytial virus (RSV) have been reported worldwide. We conducted a systematic review on articles identified in PubMed reporting RSV seasonality based on data collected before 1 January 2020. RSV seasonal patterns were examined by geographic location, calendar month, analytic method, and meteorological factors including temperature and absolute humidity. Correlation and regression analyses were conducted to explore the relationship between RSV seasonality and study methods and characteristics of study locations. RSV seasons were reported in 209 articles published in 1973-2023 for 317 locations in 77 countries. Regular RSV seasons were similarly reported in countries in temperate regions, with highly variable seasons identified in subtropical and tropical countries. Longer durations of RSV seasons were associated with a higher daily average mean temperature and daily average mean absolute humidity. The global seasonal patterns of RSV provided important information for optimizing interventions against RSV infection.

Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022-2023 season

Background

Respiratory syncytial virus (RSV) is a common cause of upper and lower respiratory tract infections. This study aimed to explore the prevalence of respiratory syncytial virus (RSV) and other respiratory viruses in Bulgaria, characterize the genetic diversity of RSV strains, and perform amino acid sequence analyses of RSV surface and internal proteins.

Methods

Clinical and epidemiological data and nasopharyngeal swabs were prospectively collected from patients with acute respiratory infections between October 2020 and May 2023. Real-time PCR for 13 respiratory viruses, whole-genome sequencing, phylogenetic, and amino acid analyses were performed.

Results

This study included three epidemic seasons (2020-2021, 2021-2022, and 2022-2023) from week 40 of the previous year to week 20 of the following year. Of the 3,047 patients examined, 1,813 (59.5%) tested positive for at least one viral respiratory pathogen. RSV was the second most detected virus (10.9%) after SARS-CoV-2 (22%). Coinfections between RSV and other respiratory viruses were detected in 68 cases, including 14 with SARS-CoV-2. After two seasons of low circulation, RSV activity increased significantly during the 2022-2023 season. The detection rates of RSV were 3.2, 6.6, and 13.7% in the first, second, and third seasons, respectively. RSV was the most common virus found in children under 5 years old with bronchiolitis (40%) and pneumonia (24.5%). RSV-B drove the 2022-2023 epidemic. Phylogenetic analysis indicated that the sequenced RSV-B strains belonged to the GB5.0.5a and GB5.0.6a genotypes. Amino acid substitutions in the surface and internal proteins, including the F protein antigenic sites were identified compared to the BA prototype strain.

Conclusion

This study revealed a strong resurgence of RSV in the autumn of 2022 after the lifting of anti-COVID-19 measures, the leading role of RSV as a causative agent of serious respiratory illnesses in early childhood, and relatively low genetic diversity in circulating RSV strains.

Respiratory Syncytial Virus Hospital-Based Burden of Disease in Children Younger Than 5 Years, 2015-2022

Importance

Respiratory syncytial virus (RSV) resurgences have been noted following the COVID-19 pandemic in many countries. Recent findings suggest that the 2021 and 2022 RSV seasons were more severe than in past seasons, and age distribution may have shifted toward older children in the younger than 5 years age group.

Objectives

To estimate age-specific changes in RSV hospital-based burden of disease before and after the COVID-19 pandemic and to compare incidence by Medicaid use.

Design, Setting, and Participants

This retrospective cohort study included children younger than 5 years diagnosed with RSV and bronchiolitis at 50 US children's hospitals in 10 US geographic regions. The included participants had an encounter in intensive care, inpatient, emergency, or observational units, between June 1, 2015, and March 31, 2023.

Exposures

Diagnosis of RSV, bronchiolitis, or both at encounter.

Main Outcome and Measures

Incidence rate ratio of hospital use within each care unit before vs after the COVID-19 pandemic. It was hypothesized a priori that incidence of hospital use would increase overall in 2021 and 2022 compared with 2015 to 2019 and that the increase would be greater among children 12 months and older.

Results

Of 924 061 study participants (median [IQR] age, 8 (5-16) months; 535 619 [58.0%] male), 348 077 (37.7%) were diagnosed with RSV. Of these, 187 850 (54.0%) were hospitalized. Incidence rate ratios of hospitalization increased for all ages in 2021 and 2022 compared with 2015 to 2019. Children aged 24 to 59 months were 4.86 (95% CI, 4.75-4.98) times as likely to be hospitalized in 2022 compared with 2015 to 2019, whereas infants aged 0 to 5 months were 1.77 (95% CI, 1.74-1.80) times as likely. Medicaid patients were more likely to be hospitalized than non-Medicaid patients regardless of year.

Conclusions and Relevance

Hospitalizations for RSV and bronchiolitis demonstrated atypical seasonality in 2021 and 2022, with an overall increase in RSV encounters. Postpandemic RSV hospitalization increased for all ages, but especially among older children, whereas bronchiolitis hospitalization was decreased or unchanged compared with earlier seasons. These findings suggest some of the observed increase in RSV hospital use may be due to increased testing.

Unmasking the potential of secretory IgA and its pivotal role in protection from respiratory viruses

Mucosal immunity has regained its spotlight amidst the ongoing Coronavirus disease 19 (COVID-19) pandemic, with numerous studies highlighting the crucial role of mucosal secretory IgA (SIgA) in protection against Severe acute respiratory syndrome coronavirus-2 or SARS-CoV-2 infections. The observed limitations in the efficacy of currently authorized COVID-19 vaccines in inducing effective mucosal immune responses remind us of the limitations of systemic vaccination in promoting protective mucosal immunity. This resurgence of interest has motivated the development of vaccine platforms capable of enhancing mucosal responses, specifically the SIgA response, and the development of IgA-based therapeutics. Recognizing viral respiratory infections as a global threat, we would like to comprehensively review the existing knowledge on mucosal immunity, with a particular emphasis on SIgA, in the context of SARS-CoV-2, influenza, and Respiratory Syncytial Virus (RSV) infections. This review aims to describe the structural and functional specificities of SIgA, along with its nuanced role in combating influenza, RSV, and SARS-CoV-2 infections. Subsequent sections further elaborate promising vaccine strategies, including mucosal vaccines against Influenza, RSV, and SARS-CoV-2 respiratory viruses, currently undergoing preclinical and clinical development. Additionally, we address the challenges associated with mucosal vaccine development, concluding with a discussion on IgA-based therapeutics as a promising platform for the treatment of viral respiratory infections. This comprehensive review not only synthesizes current insights into mucosal immunity but also identifies critical knowledge gaps, strengthening the way for further advancements in our current understanding and approaches to combat respiratory viral threats.

Trends in Respiratory Infectious Pathogens in Children Under the Age of 14 - Xiamen City, Fujian Province, China, 2017-2023

What is already known about this topic?

Respiratory infections pose a significant burden on public health. Despite recent outbreaks occurring in various locations, there is limited information available on the prevalence trends of multiple common respiratory pathogens in China beyond 2022.

What is added by this report?

A retrospective analysis was conducted on respiratory pathogen infections in a Xiamen hospital over a seven-year period. The analysis revealed fluctuating trends, with the number of infections for certain viruses initially decreasing after 2019, only to rebound to previous or higher levels. Recently, there has been an observed collective increase in positive cases for certain pathogens.

What are the implications for public health practice?

The study improves understanding of respiratory pathogens, primarily in Xiamen, with potential implications for the improvement of strategies for the prevention and management of respiratory infectious diseases.

Increased bronchiolitis burden and severity after the pandemic: a national multicentric study

BACKGROUND

The coronavirus 2019 (COVID-19) related containment measures led to the disruption of all virus distribution. Bronchiolitis-related hospitalizations shrank during 2020-2021, rebounding to pre-pandemic numbers the following year. This study aims to describe the trend in bronchiolitis-related hospitalization this year, focusing on severity and viral epidemiology.

METHODS

We conducted a retrospective investigation collecting clinical records data from all infants hospitalized for bronchiolitis during winter (1st September-31th March) from September 2018 to March 2023 in six Italian hospitals. No trial registration was necessary according to authorization no.9/2014 of the Italian law.

RESULTS

Nine hundred fifty-three infants were hospitalized for bronchiolitis this last winter, 563 in 2021-2022, 34 in 2020-2021, 395 in 2019-2020 and 483 in 2018-2019. The mean length of stay was significantly longer this year compared to all previous years (mean 7.2 ± 6 days in 2022-2023), compared to 5.7 ± 4 in 2021-2022, 5.3 ± 4 in 2020-2021, 6.4 ± 5 in 2019-2020 and 5.5 ± 4 in 2018-2019 (p < 0.001), respectively. More patients required mechanical ventilation this winter 38 (4%), compared to 6 (1%) in 2021-2022, 0 in 2020-2021, 11 (2%) in 2019-2020 and 6 (1%) in 2018-2019 (p < 0.05), respectively. High-flow nasal cannula and non-invasive respiratory supports were statistically more common last winter (p = 0.001 or less). RSV prevalence and distribution did not differ this winter, but coinfections were more prevalent 307 (42%), 138 (31%) in 2021-2022, 1 (33%) in 2020-2021, 68 (23%) in 2019-2020, 61 (28%) in 2018-2019 (p = 0.001).

CONCLUSIONS

This study shows a growth of nearly 70% in hospitalisations for bronchiolitis, and an increase in invasive respiratory support and coinfections, suggesting a more severe disease course this winter compared to the last five years.

Investigating epidemiological distribution (temporality and intensity) of respiratory pathogens following COVID-19 de-escalation process in Catalonia, September 2016-June 2021: Analysis of regional surveillance data

BACKGROUND

Following the low incidence rates of non-SARS-CoV-2 respiratory viruses registered during the strict lockdown enforced in the pandemic, a resurgence of several endemic viruses in Catalonia (Spain) was noted during the early summer of 2021.

OBJECTIVES

In this study, we investigated whether the circulation of non-SARS-CoV-2 respiratory viruses in Catalonia, assessed by Microbiological Reporting System of Catalonia (MRSC) and the Epidemiological Surveillance Network of Catalonia, was affected by the strict lockdown measures, as well as, the implication of the Coronavirus Disease 19 (COVID-19) de-escalation process in the late season outbreaks registered during the 2020-2021 season.

STUDY DESIGN

A retrospective comparison of epidemic patterns in the respiratory viruses' incidence, using regional public health surveillance data from MRSC, was performed between weeks 26/2016 to week 27/2021. Data were expressed as the weekly total number of test positivity for individual viruses. A segmented negative binomial regression model was conducted, with two parameters included (level and trend) for each segment of the time series (2020 pre-lockdown, 2020 post-lockdown and 2021). Results were reported as a unit changed in the strict lockdown.

RESULTS

A total of 51588 confirmed cases of the different respiratory viruses were included in the analysis, the majority were influenza cases (63.7%). An immediate reduction in the weekly number of cases was observed in 2020 after the COVID-19 outbreak for human adenovirus virus (HAdV) (β2 = -2.606; P <0.01), human parainfluenza virus (HPIV) (β2 = -3.023; P <0.01), influenza virus (IFV) (β2 = -1.259; P <0.01), but not for respiratory syncytial virus (RSV), where the number of cases remained unchanged. During 2020, a significant negative trend was found for RSV (β3 = -0.170, P <0.01), and a positive trend for HAdV (β3 = 0.075, P <0.01). During 2021, a significant reduction in the weekly number of cases was also observed for all respiratory viruses, and a borderline non-significant reduction for HPIV (β3 = -0.027; P = 0.086). Moreover, significant positive trends were found for each viral pathogen, except for influenza during 2020-2021 season, where cases remained close to zero. The respiratory viruses increased activity and their late season epidemic start particularly affected children under 6 years old.

CONCLUSIONS

Our data not only provides evidence that occurrence of different respiratory virus infections was affected by the strict lockdown taken against SARS-CoV-2 but it also shows a late resurgence of seasonal respiratory viruses' cases during the 2020-2021 season following the relaxation of COVID-19-targeted non-pharmaceutical interventions.

Assessing the impact of COVID-19 on epidemiological changes of severe pediatric respiratory syncytial virus infections in Malaysia

Introduction

Respiratory syncytial virus (RSV) is one of the leading causes of hospitalization and mortality among children with respiratory tract infections. The non-pharmaceutical preventive measures against severe acute respiratory syndrome coronavirus (COVID-19) may have reduced the transmission of RSV, altering its tropical epidemiological seasonality. Thus, this study represents the first attempt to evaluate changes in RSV epidemiology in the context of COVID-19 pandemic in Malaysia.

Methods

Conducted at a tertiary hospital in Kuala Lumpur, Malaysia, this retrospective study analyzed collated data of children aged <12 years who were admitted for severe respiratory infections from 2017 to 2022. Time series models were used to predict the differences between actual and forecasted RSV cases, while logistic regression assessed the statistical association between RSV and COVID-19.

Results

Among the 4,084 children analyzed, we reported a significant inverse relationship between RSV and COVID-19 infections during the pandemic (2020-2021) (p < 0.05). In 2020, the RSV positivity rate sharply declined to 8.3 and 5.9%, respectively, in the two prominent seasons. Time series analysis showed a tremendous decrease in cases compared to the expected values, with reductions of 98.3% in the first season and 95.7% in the second season. However, following the lifting of the restriction order in 2022, RSV infections rose sharply with a positivity rate of 36.3%, higher than pre-COVID-19 pandemic levels.

Conclusion

This study provides evidence of increasing RSV cases post-COVID-19 pandemic, due to immunity debt. Hence, the healthcare system must be prepared to address future RSV outbreaks with the appropriate implementation of prophylaxis and public health measures.

Epidemiology and clinical features of respiratory syncytial virus (RSV) infection in hospitalized children during the COVID-19 pandemic in Gorgan, Iran

Background and Aims

Respiratory syncytial virus (RSV) is a leading cause of acute respiratory infection in infants and young children. Given the altered circulation patterns of respiratory viruses during the coronavirus disease pandemic-2019 (COVID-19), the study aimed to evaluate epidemiology and clinical features of RSV infections in hospitalized children during the COVID-19 pandemic in Gorgan, northeastern Iran. Molecular epidemiology studies on respiratory viral infections are necessary to monitor circulating viruses, disease severity, and clinical symptoms, in addition to early warning of new outbreaks.

Methods

Overall, 411 respiratory swab samples from hospitalized children from October 2021 to March 2022 were collected at Taleghani Children's Hospital, Gorgan, Iran. The incidence of RSV, as well as the circulating subgroups and genotypes, were investigated and confirmed using PCR methods. Additionally, all samples tested for severe acute respiratory syndrome-associated coronavirus 2 (SARS-CoV-2) and influenza, and demographic and clinical data were analyzed using SPSS software.

Results

The share of RSV, SARS-CoV-2, and influenza among hospitalized children with acute lower respiratory infections (ALRI) were 27%, 16.5%, and 4.1%, respectively. The RSV subgroup A (genotype ON1) was dominant over subgroup B (genotype BA9), with more severe clinical symptoms. Compared with the prepandemic era there were high numbers of hospitalized SARS-CoV-2 positive children and low numbers of other respiratory viruses. Despite this, the prevalence of ALRI-related RSV-disease among hospitalized children in our specialized pediatric center was higher than COVID-19 disease in the same cohort.

Conclusions

Studying the epidemiology of respiratory viruses and determining the circulating strains can contribute to effective infection control and treatment strategies.

Spatiotemporal variations of "triple-demic" outbreaks of respiratory infections in the United States in the post-COVID-19 era

BACKGROUND

The US confronted a "triple-demic" of influenza, respiratory syncytial virus (RSV), and COVID-19 in the winter of 2022, leading to increased respiratory infections and a higher demand for medical supplies. It is urgent to analyze these epidemics and their spatial-temporal co-occurrence, identifying hotspots and informing public health strategies.

METHODS

We employed retrospective and prospective space-time scan statistics to assess the situations of COVID-19, influenza, and RSV in 51 US states from October 2021 to February 2022, and from October 2022 to February 2023, respectively. This enabled monitoring of spatiotemporal variations for each epidemic individually and collectively.

RESULTS

Compared to winter 2021, COVID-19 cases decreased while influenza and RSV infections significantly increased in winter 2022. We found a high-risk cluster of influenza and COVID-19 (not all three) in winter 2021. In late November 2022, a large high-risk cluster of triple-demic emerged in the central US. The number of states at high risk for multiple epidemics increased from 15 in October 2022 to 21 in January 2023.

CONCLUSIONS

Our study offers a novel spatiotemporal approach that combines both univariate and multivariate surveillance, as well as retrospective and prospective analyses. This approach offers a more comprehensive and timely understanding of how the co-occurrence of COVID-19, influenza, and RSV impacts various regions within the United States. Our findings assist in tailor-made strategies to mitigate the effects of these respiratory infections.

Respiratory syncytial virus in children: epidemiology and clinical impact post-COVID-19

PURPOSE OF REVIEW

Respiratory syncytial virus (RSV) remains a leading cause of mortality and morbidity worldwide. RSV seasonality was disrupted by COVID-19-associated nonpharmaceutical interventions (NPIs). We review RSV seasonality, molecular epidemiology, clinical manifestations, and community awareness to inform future prevention strategies.

RECENT FINDINGS

An initial reduction of RSV disease observed with NPIs, and subsequent global resurgence was associated with a collapse in genetic diversity. A lack of immunity is suggested to have contributed to the resurgence of RSV cases experienced post COVID-19. The median age of children admitted with RSV increased during the resurgence, likely secondary to the expanded cohort of RSV-immune naive children. The pandemic also played a role in increased community awareness, which can be utilized as part of a coordinated public health effort to introduce prevention strategies. Further education on signs and symptoms of RSV is still required.

SUMMARY

mAbs and maternal vaccines targeting RSV have the potential to reduce paediatric morbidity, however this new era of RSV prevention will require ongoing research to facilitate community awareness and engagement, and better respiratory surveillance. Tackling the global burden of RSV will require a coordinated effort and measures to ensure access and affordability of new prevention strategies.

Respiratory syncytial virus in pediatric patients with severe acute respiratory infections in Senegal: findings from the 2022 sentinel surveillance season

In 2022, many regions around the world experienced a severe respiratory syncytial virus (RSV) epidemic with an earlier-than-usual start and increased numbers of paediatric patients in emergency departments. Here we carried out this study to describe the epidemiology and genetic characteristics of RSV infection in patients hospitalized with severe acute respiratory infections in 2022. Samples were tested for RSV by multiplex real time reverse transcription polymerase chain reaction. Subsequently, a subset of RSV positive samples was selected for NGS sequencing. RSV was detected in 16.04%, among which RSV-A was confirmed in 7.5% and RSV-B in 76.7%. RSV infection were more identified in infants aged ≤ 11 months (83.3%) and a shift in the circulation pattern was observed, with highest incidences between September-November. Phylogenetic analyses revealed that all RSV-A strains belonged to GA2.3.5 genotype and all RSV-B strains to GB5.0.5a genotype. Three putative N-glycosylation sites at amino acid positions 103, 135, 237 were predicted among RSV-A strains, while four N-linked glycosylation sites at positions 81, 86, 231 and 294 were identified in RSV-B strains. Globally, our findings reveal an exclusive co-circulation of two genetic lineages of RSV within the pediatric population in Senegal, especially in infants aged ≤ 11 months.

Measures against COVID-19 affected the spread of human enteric viruses in a Swedish community, as found when monitoring wastewater

The quantification of viral genomes in wastewater reflects the prevalence of viral infections within the community. Knowledge of how the spread of common enteric viruses in the community was affected by the Swedish COVID-19 interventions is limited. To investigate this, the weekly wastewater samples collected for monitoring SARS-CoV-2 throughout the COVID-19 pandemic at the Rya sewage treatment plant in Gothenburg were also analyzed for adenovirus, norovirus GII, astrovirus, and rotavirus. The amount of each viral genome was quantified by real-time-qPCR and compared with the quantity of these viral genomes in wastewater from 2017. The results showed that the winter seasonality of norovirus GII and rotavirus in wastewater observed in 2017 was interrupted shortly after the introduction of the COVID-19 interventions, and they remained at low level throughout the pandemic. The circulation pattern of astrovirus and adenovirus was less affected. When the COVID-19 restrictions were lifted in 2022, a dramatic increase was observed in the amount of norovirus GII, rotavirus, and adenovirus genomes in wastewater. The changes in abundance and seasonality of some viruses identified through wastewater monitoring were consistent with changes in the number of patients diagnosed with these viruses. These findings suggest that moderate intervention to prevent COVID-19 significantly reduced the spread of some enteric viruses in the community. The results show that wastewater monitoring is a valuable tool for detecting the spread and outbreaks of viral infections that may cause gastroenteritis also when people do not seek medical help, such as during the COVID-19 pandemic.

Respiratory virus surveillance in hospitalized children less than two-years of age in Kenema, Sierra Leone during the COVID-19 pandemic (October 2020- October 2021)

Globally, viral pathogens are the leading cause of acute respiratory infection in children under-five years. We aim to describe the epidemiology of viral respiratory pathogens in hospitalized children under-two years of age in Eastern Province of Sierra Leone, during the second year of the SARS-CoV-2 pandemic. We conducted a prospective study of children hospitalized with respiratory symptoms between October 2020 and October 2021. We collected demographic and clinical characteristics and calculated each participant´s respiratory symptom severity. Nose and throat swabs were collected at enrollment. Total nucleic acid was purified and tested for multiple respiratory viruses. Statistical analysis was performed using R version 4.2.0 software. 502 children less than two-years of age were enrolled. 376 (74.9%) had at least one respiratory virus detected. The most common viruses isolated were HRV/EV (28.2%), RSV (19.5%) and PIV (13.1%). Influenza and SARS-CoV-2 were identified in only 9.2% and 3.9% of children, respectively. Viral co-detection was common. Human metapneumovirus and RSV had more than two-fold higher odds of requiring O2 therapy while hospitalized. Viral pathogen prevalence was high (74.9%) in our study population. Despite this, 100% of children received antibiotics, underscoring a need to expand laboratory diagnostic capacity and to revisit clinical guidelines implementation in these children. Continuous surveillance and serologic studies among more diverse age groups, with greater geographic breadth, are needed in Sierra Leone to better characterize the long-term impact of COVID-19 on respiratory virus prevalence and to better characterize the seasonality of respiratory viruses in Sierra Leone.

Respiratory Syncytial Virus Infections in Polish Pediatric Patients from an Expert Perspective

Respiratory syncytial virus (RSV) is the most common pathogen causing respiratory tract infections in infants, affecting over 90% of children within the first two years of life. It may cause lower respiratory tract infections, which constitute a significant healthcare burden both in the primary and secondary care settings. Meanwhile, the data regarding RSV disease in Poland is scarce, and published data significantly differs from the numbers reported for other countries with longstanding surveillance and reporting systems. A literature review and an expert panel were conducted to (1) understand the healthcare burden of RSV infections in Poland; (2) collect data on infection seasonality, patient pathway, and management patterns; and (3) evaluate RSV infection surveillance in Poland. According to the literature, RSV is the major agent responsible for non-influenza respiratory diseases in Poland. The reported rates of hospitalization for RSV infections are 267.5/100,000 for children under 5 years of age and 1132.1/100,000 for those under 1 year of age. Comparisons with data from other countries suggest that these values may be underestimated, possibly due to insufficient access to microbiological testing and a low awareness of RSV. Infections occur mainly between December and April, however, this pattern has changed following the implementation of preventive measures for coronavirus disease 2019 in the past few years. According to available reports, bronchodilators, antibiotics, corticosteroids, and X-ray imaging have been frequently used. The surveillance system in Poland has limitations, but these may be overcome due to recent changes in healthcare law as well as the availability and reimbursement of diagnostic tests.

Impact of COVID-19 on the changing pattern of human orthopneumovirus (respiratory syncytial virus) infection in Iran

BACKGROUND

Human orthopneumovirus (HOPV) or respiratory syncytial virus (RSV) is one of the important causes of acute respiratory infections (ARIs) during the cold months of the year worldwide. Many countries have reported an absence of ARIs due to HOPV during the winter of 2020-2021 associated with preventive measures to reduce the spread of SARS-CoV2. However, with the reduction of COVID-19 public health restrictions and the absence of immunity in the community due to the lack of exposure in the previous season, many countries had a delayed HOPV outbreak. Here we reported the impact of COVID-19 on the changing pattern of HOPV infection in Iran.

METHODS

Throat and nasopharyngeal swab samples were collected from patients (children and adults) with ARIs and sent to the Iran National Influenza Center. After RNA extraction, Real time RT-PCR was performed for HOPV detection.

RESULTS

In 260 samples collected from patients with ARIs in three different groups, which included children in March 2021, pilgrims in July 2022, and outpatients during November and December 2022, no HOPV was detected in any group.

CONCLUSIONS

The lack of HOPV activity in Iran during the winter of 2020-2021 and then the resurgence in spring 2022 and again the absence of activity in summer and autumn 2022 was extraordinary in the HOPV epidemiology, and probably due to the implementation of public health non-pharmaceutical interventions to reduce the spread of SARS-CoV2. Although it is not possible to keep such restrictions, similar methods can be taken to control outbreaks caused by respiratory viruses.

The long-term boomerang effect of COVID-19 on admissions for non-COVID diseases: the ECIEN-2022 study

Since COVID-19 pandemic started, many changes have been seen in the cycling patterns of pediatric pathologies. On year 2020, we described the initial effects of COVID-19, with a significant decrease in emergency visits and admissions, but 2 years later the situation seems to be reversed. Our study bridges a literature gap by exploring the lasting effects of COVID-19 on pediatric non-COVID admissions, particularly the resurgence of respiratory illnesses. ECIEN-2022 is a single-center, retrospective, observational-study conducted 3 years after the pandemic onset, to describe the long-term effects of COVID-19 in pediatric admissions for non-COVID diseases. Admissions during year 2022 were compared with the Pre-Pandemic Period (PPP: 2015-2019). Pediatric Emergency Department (P-ED) visits, hospital, and Intensive Care Unit (P-ICU) admissions were compared across pre- and post-pandemic periods. Monthly distribution and year-waves are presented. P-ED monthly visits (mean and Standard deviation (SD) raised from 3521 (533) in the PPP to 3775 (996) in 2022 (p < 0.001). Monthly hospital admissions in the 3rd quarter of the Pre-Pandemic Period were 111.7/month (SD:29), dropped to 88.5(SD:6.5) in 2020 and raised to 149(SD:38.8) in 2022 (p = 0.036). An increase in respiratory illnesses was observed in 2022 compared to PPP; Bronchiolitis increased 38%, bronchitis 56%, and admissions for Respiratory Syncytial Virus 67%.  Conclusion: COVID-19 pandemic has had a significant impact on the use and nature of pediatric health services. The initial decrease has been followed by a boomerang effect with an increase of cases, mainly due to an increase in respiratory infections when pandemic control measures and social restrictions have been lifted. It is essential to maintain an active surveillance and monitorization of these patterns to ensure appropriate healthcare access and utilization. What is Known: • COVID-19 pandemic initially led to a significant decrease in emergency visits and admissions for non-COVID diseases. What is New: • ECIEN-2022 study investigated the long-term effects of COVID-19 on pediatric admissions for non-COVID diseases, detecting a "boomerang effect" with an increase in pediatric admissions for non-COVID diseases in year 2022. • Pediatric Emergency Department visits and hospital admissions for non-COVID diseases, especially those due to respiratory infections, increased significantly in 2022 when compared to the Pre-Pandemic Period.

Molecular Epidemiology and Genetic Diversity of Human Respiratory Syncytial Virus in Sicily during Pre- and Post-COVID-19 Surveillance Seasons

Human respiratory syncytial virus (hRSV) is an important pathogen of acute respiratory tract infection of global significance. In this study, we investigated the molecular epidemiology and the genetic variability of hRSV over seven surveillance seasons between 2015 and 2023 in Sicily, Italy. hRSV subgroups co-circulated through every season, although hRSV-B mostly prevailed. After the considerable reduction in the circulation of hRSV due to the widespread implementation of non-pharmaceutical preventive measures during the COVID-19 pandemic, hRSV rapidly re-emerged at a high intensity in 2022-2023. The G gene was sequenced for genotyping and analysis of deduced amino acids. A total of 128 hRSV-A and 179 hRSV-B G gene sequences were obtained. The phylogenetic analysis revealed that the GA2.3.5a (ON1) and GB5.0.5a (BA9) genotypes were responsible for the hRSV epidemics in Sicily.; only one strain belonged to the genotype GB5.0.4a. No differences were observed in the circulating genotypes during pre- and post-pandemic years. Amino acid sequence alignment revealed the continuous evolution of the G gene, with a combination of amino acid changes specifically appearing in 2022-2023. The predicted N-glycosylation sites were relatively conserved in ON1 and BA9 genotype strains. Our findings augment the understanding and prediction of the seasonal evolution of hRSV at the local level and its implication in the monitoring of novel variants worth considering in better design of candidate vaccines.

Development and Validation of a High-Performance Liquid Chromatography with Tandem Mass Spectrometry (HPLC-MS/MS) Method for Quantification of Major Molnupiravir Metabolite (β-D-N4-hydroxycytidine) in Human Plasma

Molnupiravir is an antiviral drug against viral RNA polymerase activity approved by the FDA for the treatment of COVID-19, which is metabolized to β-D-N4-hydroxycytidine (NHC) in human blood plasma. A novel method was developed and validated for quantifying NHC in human plasma within the analytical range of 10-10,000 ng/mL using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) to support pharmacokinetics studies. For sample preparation, the method of protein precipitation by acetonitrile was used, with promethazine as an internal standard. Chromatographic separation was carried out on a Shim-pack GWS C18 (150 mm × 4.6 mm, 5 μm) column in a gradient elution mode. A 0.1% formic acid solution in water with 0.08% ammonia solution (eluent A, v/v) and 0.1% formic acid solution in methanol with 0.08% ammonia solution mixed with acetonitrile in a 4:1 ratio (eluent B, v/v) were used as a mobile phase. Electrospray ionization (ESI) was used as an ionization source. The developed method was validated in accordance with the Eurasian Economic Union (EAEU) rules, based on the European Medicines Agency (EMA) and Food and Drug Administration (FDA) guidelines for the following parameters and used within the analytical part of the clinical study of molnupiravir drugs: selectivity, suitability of standard sample, matrix effect, calibration curve, accuracy, precision, recovery, lower limit of quantification (LLOQ), carryover, and stability.

Respiratory Syncytial Virus-An Update for Prenatal and Primary Health Providers

Respiratory syncytial virus (RSV) infection is a significant cause of morbidity and mortality among infants aged younger than 1 year, adults aged 65 years or older, and immunocompromised persons. Limited data exist on RSV infection in pregnancy and further research is needed. Strides are being made to develop vaccines, including vaccines for maternal immunization, as well as monoclonal antibodies for disease prevention.

Spatiotemporal Variations of "Triple-demic" Outbreaks of Respiratory Infections in the United States in the Post-COVID-19 Era

Objectives

The United States confronted a "triple-demic" of influenza, respiratory syncytial virus, and COVID-19 in the winter of 2022, resulting in increased respiratory infections and a higher demand for medical supplies. It is urgent to analyze each epidemic and their co-occurrence in space and time to identify hotspots and provide insights for public health strategy.

Methods

We used retrospective space-time scan statistics to retrospect the situation of COVID-19, influenza, and RSV in 51 US states from October 2021 to February 2022, and then applied prospective space-time scan statistics to monitor spatiotemporal variations of each individual epidemic, respectively and collectively from October 2022 to February 2023.

Results

Our analysis indicated that compared to the winter of 2021, COVID-19 cases decreased while influenza and RSV infections increased significantly during the winter of 2022. We revealed that a twin-demic high-risk cluster of influenza and COVID-19 but no triple-demic clusters emerged during the winter of 2021. We further identified a large high-risk cluster of triple-demic in the central US from late November, with COVID-19, influenza, and RSV having relative risks of 1.14, 1.90, and 1.59, respectively. The number of states at high risk for multiple-demic increased from 15 in October 2022 to 21 in January 2023.

Conclusion

Our study provides a novel spatiotemporal perspective to explore and monitor the transmission patterns of the triple epidemic, which could inform public health authorities' resource allocation to mitigate future outbreaks.

Respiratory Syncytial Virus Infection: Treatments and Clinical Management

Respiratory syncytial virus (RSV) is a major healthcare concern, especially for immune-compromised individuals and infants below 5 years of age. Worldwide, it is known to be associated with incidences of morbidity and mortality in infants. Despite the seriousness of the issue and continuous rigorous scientific efforts, no approved vaccine or available drug is fully effective against RSV. The purpose of this review article is to provide insights into the past and ongoing efforts for securing effective vaccines and therapeutics against RSV. The readers will be able to confer the mechanism of existing therapies and the loopholes that need to be overcome for future therapeutic development against RSV. A methodological approach was applied to collect the latest data and updated results regarding therapeutics and vaccine development against RSV. We outline the latest throughput vaccination technologies and prophylactic development efforts linked with RSV. A range of vaccination approaches with the already available vaccine (with limited use) and those undergoing trials are included. Moreover, important drug regimens used alone or in conjugation with adjuvants or vaccines are also briefly discussed. After reading this article, the audience will be able to understand the current standing of clinical management in the form of the vaccine, prophylactic, and therapeutic candidates against RSV. An understanding of the biological behavior acting as a reason behind the lack of effective therapeutics against RSV will also be developed. The literature indicates a need to overcome the limitations attached to RSV clinical management, drugs, and vaccine development that could be explained by dealing with the challenges of current study designs with continuous improvement and further work and approval on novel therapeutic applications.

Trends in Hospitalization and Mortality for Influenza and Other Respiratory Viruses during the COVID-19 Pandemic in the United States

Seasonal epidemics of respiratory viruses, respiratory syncytial virus (RSV), influenza viruses, parainfluenza viruses (PIVs), and human metapneumovirus (MPV) are associated with a significant healthcare burden secondary to hundreds of thousands of hospitalizations every year in the United States (US) alone. Preventive measures implemented to reduce the spread of SARS-CoV-2 (COVID-19 infection), including facemasks, hand hygiene, stay-at-home orders, and closure of schools and local/national borders may have impacted the transmission of these respiratory viruses. In this study, we looked at the hospitalization and mortality trends for various respiratory viral infections from January 2017 to December 2020. We found a strong reduction in all viral respiratory infections, with the lowest admission rates and mortality in the last season (2020) compared to the corresponding months from the past three years (2017-2019). This study highlights the importance of public health interventions implemented during the COVID-19 pandemic, which had far-reaching public health benefits. Appropriate and timely use of these measures may help to reduce the severity of future seasonal respiratory viral outbreaks as well as their burden on already strained healthcare systems.

The changed endemic pattern of human adenovirus from species B to C among pediatric patients under the pressure of non-pharmaceutical interventions against COVID-19 in Beijing, China

BACKGROUND

Under the pressure of non-pharmaceutical interventions (NPIs) targeting severe acute respiratory syndrome coronavirus 2, the prevalence of human adenovirus (HAdV) was monitored before and after NPIs launched on Jan 24, 2020 in pediatric patients in Beijing, China.

METHODS

Respiratory samples collected from children hospitalized with acute respiratory infections from Jan 2015 to Dec 2021 were screened by direct immunofluorescence test or capillary electrophoresis-based multiplex PCR assay. The hexon, penton base, and fiber genes were amplified from HAdV positive specimens, then sequenced. For HAdV typing, phylogenetic trees were built by MEGA X. Then clinical data of HAdV positive cases were collected. All data were evaluated using SPSS Statistics 22.0 software.

RESULTS

A total of 16,097 children were enrolled and 466 (2.89%, 466/16,097) were HAdV-positive. The positive rates of HAdV varied, ranging from 4.39% (151/3,438) in 2018 to1.25% (26/2,081) in 2021, dropped from 3.19% (428/13,408) to 1.41% (38/2,689) from before to after NPIs launched (P < 0.001). There were 350 cases typed into nine types of species B, C, or E and 34 recorded as undetermined. Among them, HAdV-B3 (51.56%, 198/384) was the most prevalent types from 2015 to 2017, and HAdV-B7 (29.17%, 112/384) co-circulated with HAdV-B3 from 2018 to 2019. After NPIs launched, HAdV-B3 and B7 decreased sharply with HAdV-B7 undetected in 2021, while HAdV-C1 became the dominant one and the undetermined were more.

CONCLUSIONS

The endemic pattern of HAdV changed in Beijing because of the NPIs launched for COVID-19. Especially, the dominant types changed from HAdV-B to HAdV-C.

COVID-19 and Influenza Coinfection Outcomes among Hospitalized Patients in the United States: A Propensity Matched Analysis of National Inpatient Sample

This study aims to provide comparative data on clinical features and in-hospital outcomes among U.S. adults admitted to the hospital with COVID-19 and influenza infection using a nationwide inpatient sample (N.I.S.) data 2020. Data were collected on patient characteristics and in-hospital outcomes, including patient's age, race, sex, insurance status, median income, length of stay, mortality, hospitalization cost, comorbidities, mechanical ventilation, and vasopressor support. Additional analysis was performed using propensity matching. In propensity-matched cohort analysis, influenza-positive (and COVID-positive) patients had higher mean hospitalization cost (USD 129,742 vs. USD 68,878, p = 0.04) and total length of stay (9.9 days vs. 8.2 days, p = 0.01), higher odds of needing mechanical ventilation (OR 2.01, 95% CI 1.19-3.39), and higher in-hospital mortality (OR 2.09, 95% CI 1.03-4.24) relative to the COVID-positive and influenza-negative cohort. In conclusion, COVID-positive and influenza-negative patients had lower hospital charges, shorter hospital stays, and overall lower mortality, thereby supporting the use of the influenza vaccine in COVID-positive patients.

Prevalence of Human Coronaviruses in Children and Phylogenetic Analysis of HCoV-OC43 during 2016-2022 in Riyadh, Saudi Arabia

With the emergence of SARS-CoV-2, routine surveillance combined with sequence and phylogenetic analysis of coronaviruses is urgently required. In the current study, the four common human coronaviruses (HCoVs), OC43, NL63, HKU1, and 229E, were screened in 361 clinical samples collected from hospitalized children with respiratory symptoms during four winter seasons. RT-PCR-based detection and typing revealed different prevalence rates of HCoVs across the four seasons. Interestingly, none of the four HCoVs were detected in the samples (n = 100) collected during the winter season of the COVID-19 pandemic. HCoV-OC43 (4.15%) was the most frequently detected, followed by 229E (1.1%). Partial sequences of S and N genes of OC43 from the winter seasons of 2015/2016 and 2021/2022 were used for sequence and phylogenetic analysis. Multiple sequence alignment of the two Saudi OC43s strains with international strains revealed the presence of sequence deletions and several mutations, of which some changed their corresponding amino acids. Glycosylation profiles revealed a number of O-and N-glycosylation sites in both genes. Based on phylogenetic analysis, four genotypes were observed with Riyadh strains grouped into the genotype C. Further long-term surveillance with a large number of clinical samples and sequences is necessary to resolve the circulation patterns and evolutionary kinetics of OC43 in Saudi Arabia.