Coinfections of the Respiratory Tract: Viral Competition for Resources

Sentinel Enhanced Dengue Surveillance System - Puerto Rico, 2012-2022

Problem/Condition

Dengue is the most prevalent mosquitoborne viral illness worldwide and is endemic in Puerto Rico. Dengue's clinical spectrum can range from mild, undifferentiated febrile illness to hemorrhagic manifestations, shock, multiorgan failure, and death in severe cases. The disease presentation is nonspecific; therefore, various other illnesses (e.g., arboviral and respiratory pathogens) can cause similar clinical symptoms. Enhanced surveillance is necessary to determine disease prevalence, to characterize the epidemiology of severe disease, and to evaluate diagnostic and treatment practices to improve patient outcomes. The Sentinel Enhanced Dengue Surveillance System (SEDSS) was established to monitor trends of dengue and dengue-like acute febrile illnesses (AFIs), characterize the clinical course of disease, and serve as an early warning system for viral infections with epidemic potential.

Reporting Period

May 2012-December 2022.

Description of System

SEDSS conducts enhanced surveillance for dengue and other relevant AFIs in Puerto Rico. This report includes aggregated data collected from May 2012 through December 2022. SEDSS was launched in May 2012 with patients with AFIs from five health care facilities enrolled. The facilities included two emergency departments in tertiary acute care hospitals in the San Juan-Caguas-Guaynabo metropolitan area and Ponce, two secondary acute care hospitals in Carolina and Guayama, and one outpatient acute care clinic in Ponce. Patients arriving at any SEDSS site were eligible for enrollment if they reported having fever within the past 7 days. During the Zika epidemic (June 2016-June 2018), patients were eligible for enrollment if they had either rash and conjunctivitis, rash and arthralgia, or fever. Eligibility was expanded in April 2020 to include reported cough or shortness of breath within the past 14 days. Blood, urine, nasopharyngeal, and oropharyngeal specimens were collected at enrollment from all participants who consented. Diagnostic testing for dengue virus (DENV) serotypes 1-4, chikungunya virus, Zika virus, influenza A and B viruses, SARS-CoV-2, and five other respiratory viruses was performed by the CDC laboratory in San Juan.

Results

During May 2012-December 2022, a total of 43,608 participants with diagnosed AFI were enrolled in SEDSS; a majority of participants (45.0%) were from Ponce. During the surveillance period, there were 1,432 confirmed or probable cases of dengue, 2,293 confirmed or probable cases of chikungunya, and 1,918 confirmed or probable cases of Zika. The epidemic curves of the three arboviruses indicate dengue is endemic; outbreaks of chikungunya and Zika were sporadic, with case counts peaking in late 2014 and 2016, respectively. The majority of commonly identified respiratory pathogens were influenza A virus (3,756), SARS-CoV-2 (1,586), human adenovirus (1,550), respiratory syncytial virus (1,489), influenza B virus (1,430), and human parainfluenza virus type 1 or 3 (1,401). A total of 5,502 participants had confirmed or probable arbovirus infection, 11,922 had confirmed respiratory virus infection, and 26,503 had AFI without any of the arboviruses or respiratory viruses examined.

Interpretation

Dengue is endemic in Puerto Rico; however, incidence rates varied widely during the reporting period, with the last notable outbreak occurring during 2012-2013. DENV-1 was the predominant virus during the surveillance period; sporadic cases of DENV-4 also were reported. Puerto Rico experienced large outbreaks of chikungunya that peaked in 2014 and of Zika that peaked in 2016; few cases of both viruses have been reported since. Influenza A and respiratory syncytial virus seasonality patterns are distinct, with respiratory syncytial virus incidence typically reaching its annual peak a few weeks before influenza A. The emergence of SARS-CoV-2 led to a reduction in the circulation of other acute respiratory viruses.

Public Health Action

SEDSS is the only site-based enhanced surveillance system designed to gather information on AFI cases in Puerto Rico. This report illustrates that SEDSS can be adapted to detect dengue, Zika, chikungunya, COVID-19, and influenza outbreaks, along with other seasonal acute respiratory viruses, underscoring the importance of recognizing signs and symptoms of relevant diseases and understanding transmission dynamics among these viruses. This report also describes fluctuations in disease incidence, highlighting the value of active surveillance, testing for a panel of acute respiratory viruses, and the importance of flexible and responsive surveillance systems in addressing evolving public health challenges. Various vector control strategies and vaccines are being considered or implemented in Puerto Rico, and data from ongoing trials and SEDSS might be integrated to better understand epidemiologic factors underlying transmission and risk mitigation approaches. Data from SEDSS might guide sampling strategies and implementation of future trials to prevent arbovirus transmission, particularly during the expansion of SEDSS throughout the island to improve geographic representation.

From intramuscular to nasal: unleashing the potential of nasal spray vaccines against coronavirus disease 2019

Coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected 700 million people worldwide since its outbreak in 2019. The current pandemic strains, including Omicron and its large subvariant series, exhibit strong transmission and stealth. After entering the human body, the virus first infects nasal epithelial cells and invades host cells through the angiotensin-converting enzyme 2 receptor and transmembrane serine protease 2 on the host cell surface. The nasal cavity is an important body part that protects against the virus. Immunisation of the nasal mucosa produces immunoglobulin A antibodies that effectively neutralise viruses. Saline nasal irrigation, a type of physical therapy, can reduce the viral load in the nasal cavity and prevent viral infections to some extent. As a commonly used means to fight SARS-CoV-2, the intramuscular (IM) vaccine can induce the human body to produce a systemic immune response and immunoglobulin G antibody; however, the antibody is difficult to distribute to the nasal mucosa in time and cannot achieve a good preventive effect. Intranasal (IN) vaccines compensate for the shortcomings of IM vaccines, induce mucosal immune responses, and have a better effect in preventing infection. In this review, we discuss the nasal defence barrier, the harm caused by SARS-CoV-2, the mechanism of its invasion into host cells, nasal cleaning, IM vaccines and IN vaccines, and suggest increasing the development of IN vaccines, and use of IN vaccines as a supplement to IM vaccines.

OUTCOMES OF INFECTIOUS PANUVEITIS ASSOCIATED WITH SIMULTANEOUS MULTI-POSITIVE OCULAR FLUID POLYMERASE CHAIN REACTION

PURPOSE

To evaluate features of infectious panuveitis associated with multiple pathogens detected by ocular fluid sampling.

METHODS

Single-center, retrospective, consecutive case series of patients with aqueous/vitreous polymerase chain reaction testing with >1 positive result in a single sample from 2001 to 2021.

RESULTS

Of 1,588 polymerase chain reaction samples, 28 (1.76%) were positive for two pathogens. Most common pathogens were cytomegalovirus (n = 16, 57.1%) and Epstein-Barr virus (n = 13, 46.4%), followed by varicella zoster virus (n = 8, 28.6%), Toxoplasma gondii (n = 6, 21.4%), herpes simplex virus 2 (n = 6, 21.4%), herpes simplex virus 1 (n = 6, 21.4%), and Toxocara (n = 1, 3.6%). Mean initial and final visual acuity (logarithm of the minimum angle of resolution) were 1.3 ± 0.9 (Snellen ∼20/400) and 1.3 ± 1.1 (Snellen ∼20/400), respectively. Cytomegalovirus-positive eyes (n = 16, 61.5%) had a mean final visual acuity of 0.94 ± 1.1 (Snellen ∼20/175), whereas cytomegalovirus-negative eyes (n = 10, 38%) had a final visual acuity of 1.82 ± 1.0 (Snellen ∼20/1,320) ( P < 0.05). Main clinical features included intraocular inflammation (100%), retinal whitening (84.6%), immunosuppression (65.4%), retinal hemorrhage (38.5%), and retinal detachment (34.6%).

CONCLUSION

Cytomegalovirus or Epstein-Barr virus were common unique pathogens identified in multi-PCR-positive samples. Most patients with co-infection were immunosuppressed with a high rate of retinal detachment and poor final visual acuity. Cytomegalovirus-positive eyes had better visual outcomes compared with cytomegalovirus-negative eyes.

Towards Understanding and Identification of Human Viral Co-Infections

Viral co-infections, in which a host is infected with multiple viruses simultaneously, are common in the human population. Human viral co-infections can lead to complex interactions between the viruses and the host immune system, affecting the clinical outcome and posing challenges for treatment. Understanding the types, mechanisms, impacts, and identification methods of human viral co-infections is crucial for the prevention and control of viral diseases. In this review, we first introduce the significance of studying human viral co-infections and summarize the current research progress and gaps in this field. We then classify human viral co-infections into four types based on the pathogenic properties and species of the viruses involved. Next, we discuss the molecular mechanisms of viral co-infections, focusing on virus-virus interactions, host immune responses, and clinical manifestations. We also summarize the experimental and computational methods for the identification of viral co-infections, emphasizing the latest advances in high-throughput sequencing and bioinformatics approaches. Finally, we highlight the challenges and future directions in human viral co-infection research, aiming to provide new insights and strategies for the prevention, control, diagnosis, and treatment of viral diseases. This review provides a comprehensive overview of the current knowledge and future perspectives on human viral co-infections and underscores the need for interdisciplinary collaboration to address this complex and important topic.

Respiratory Viral Coinfections: Insights into Epidemiology, Immune Response, Pathology, and Clinical Outcomes

Respiratory viral coinfections are a global public health threat that poses an economic burden on individuals, families, and healthcare infrastructure. Viruses may coinfect and interact synergistically or antagonistically, or their coinfection may not affect their replication rate. These interactions are specific to different virus combinations, which underlines the importance of understanding the mechanisms behind these differential viral interactions and the need for novel diagnostic methods to accurately identify multiple viruses causing a disease in a patient to avoid misdiagnosis. This review examines epidemiological patterns, pathology manifestations, and the immune response modulation of different respiratory viral combinations that occur during coinfections using different experimental models to better understand the dynamics respiratory viral coinfection takes in driving disease outcomes and severity, which is crucial to guide the development of prevention and treatment strategies.

Respiratory virus coinfections during the COVID-19 pandemic: epidemiologic analysis and clinical outcomes from the Phase 2/3 molnupiravir trial (MOVe-OUT)

This exploratory post hoc analysis assessed the incidence of respiratory viral coinfections and their impact on clinical outcomes in non-hospitalized adults with mild-to-moderate coronavirus disease-2019 (COVID-19) treated with molnupiravir versus placebo for 5 days in the Phase 2/3 MOVe-OUT trial (NCT04575597), which took place in October 2020 to January 2021 (Phase 2, n = 302) and May 2021 to October 2021 (Phase 3, n = 1,433). Among 1,735 total randomized participants, 1,674 had a baseline respiratory pathogen panel (NxTAG Respiratory Pathogen Panel for the Luminex MAGPIX instrument) performed and 69 (4.1%) were coinfected with at least one additional respiratory viral pathogen. Human rhinovirus/enterovirus (39/69, 56.5%) was the most common coinfection detected at baseline. In the modified intention-to-treat population, two participants with coinfecting respiratory RNA viruses were hospitalized and received respiratory interventions through Day 29, and none died; one participant in the molnupiravir group was coinfected with human rhinovirus/enterovirus, and one participant in the placebo group was coinfected with human metapneumovirus. Hospitalization or death occurred in 6.2% and 9.0% of non-coinfected participants in the molnupiravir versus placebo group, respectively, and over 90% did not require respiratory interventions. Most coinfecting respiratory RNA viruses detected at baseline were not detected at the end of therapy in both the molnupiravir and placebo groups. In summary, participants coinfected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and another respiratory RNA virus were not more likely to be hospitalized or die, or require respiratory interventions, compared to participants who were not coinfected with another respiratory RNA virus at baseline in both groups.

IMPORTANCE

Respiratory viral coinfections are known to occur with coronavirus disease-2019 (COVID-19). In a cohort of non-hospitalized adults with mild-to-moderate COVID-19 treated with molnupiravir versus placebo in the MOVe-OUT trial during October 2020 to October 2021, 4.1% of participants had a documented viral coinfection; human rhinovirus/enterovirus was the most common pathogen detected with the NxTAG Respiratory Pathogen Panel assay. Participants who had a coinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and another respiratory RNA virus were not more likely to have worse clinical outcomes compared to those participants without a viral coinfection, and many coinfecting respiratory RNA viruses were no longer detected at the end of the 5-day treatment period in both groups.

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.

Epidemiological trends of respiratory tract pathogens detected via mPCR in Australian adult patients before COVID-19

BACKGROUND

Respiratory tract infections (RTIs) are a major global health burden due to their high morbidity and mortality. This retrospective study described the epidemiology of respiratory pathogens in adults over a 5-year period at an Australian tertiary healthcare network.

METHODS

All multiplex reverse transcription polymerase chain reaction respiratory samples taken between the 1st of November 2014 and the 31st of October 2019 were included in this study. Overall prevalence and variations according to seasons, age groups and sex were analysed, as well as factors associated with prolonged hospital and intensive care length of stay.

RESULTS

There were 12,453 pathogens detected amongst the 12,185 positive samples, with coinfection rates of 3.7%. Picornavirus (Rhinovirus), Influenza A and respiratory syncytial virus were the most commonly detected pathogens. Mycoplasma pneumoniae was the most commonly detected atypical bacteria. Significant differences in the prevalence of Chlamydia pneumoniae and Human metapneumovirus infections were found between sexes. Longest median length of intensive care and hospital stay was for Legionella species. Seasonal variations were evident for certain pathogens.

CONCLUSIONS

The high rates of pathogen detection and hospitalisation in this real-world study highlights the significant burden of RTIs, and the urgent need for an improved understanding of the pathogenicity as well as preventative and treatment options of RTIs.

Co-infections and immune-evading viral hybrids: A perspective

Background and Aims

Co-infections occur when two or more different types of pathogens infect the same host at the same time. Initially, it may develop via a primary infection and then later segue into a superinfection. Although some research suggests that coinfections do not affect the effect of disease outcomes, alternate evidence says otherwise. While the disease outcomes are frequently influenced by the interactions between many viruses, how these viruses interact during coinfections is poorly understood. This article aims to shed light on the interaction between viruses at a cellular and subcellular level, and the clinical implications for the same.

Methods

The articles were sought by conducting a thorough literature search on Google Scholar, ScienceDirect, PubMed, PubMed Central, Dimensions, and EBSCO Host, using keywords such as coinfections, virus, viral hybrids, and superinfection. The articles pertinent to the concept were then included.

Results

There is a growing body of evidence that suggests the formation of hybrid viral particles (HVPs) which conjugate at the cellular and subcellular level. While the formation of HVPs is bizarre, it may potentially have a profound effect on the clinical manifestations.

Conclusion

While there has been evidence of the formation of HVPs between a couple of viruses, researchers fear the existence of several other combinations, including zoonotic viruses. While this could be detrimental to the human race both at an individual-as well as a community-level, an in-depth understanding of the same may help in better management of the clinical manifestations of the disease.

Mathematical Modeling of Virus-Mediated Syncytia Formation: Past Successes and Future Directions

Many viruses have the ability to cause cells to fuse into large multi-nucleated cells, known as syncytia. While the existence of syncytia has long been known and its importance in helping spread viral infection within a host has been understood, few mathematical models have incorporated syncytia formation or examined its role in viral dynamics. This review examines mathematical models that have incorporated virus-mediated cell fusion and the insights they have provided on how syncytia can change the time course of an infection. While the modeling efforts are limited, they show promise in helping us understand the consequences of syncytia formation if future modeling efforts can be coupled with appropriate experimental efforts to help validate the models.

Mathematical Modeling of the Lethal Synergism of Coinfecting Pathogens in Respiratory Viral Infections: A Review

Influenza A virus (IAV) infections represent a substantial global health challenge and are often accompanied by coinfections involving secondary viruses or bacteria, resulting in increased morbidity and mortality. The clinical impact of coinfections remains poorly understood, with conflicting findings regarding fatality. Isolating the impact of each pathogen and mechanisms of pathogen synergy during coinfections is challenging and further complicated by host and pathogen variability and experimental conditions. Factors such as cytokine dysregulation, immune cell function alterations, mucociliary dysfunction, and changes to the respiratory tract epithelium have been identified as contributors to increased lethality. The relative significance of these factors depends on variables such as pathogen types, infection timing, sequence, and inoculum size. Mathematical biological modeling can play a pivotal role in shedding light on the mechanisms of coinfections. Mathematical modeling enables the quantification of aspects of the intra-host immune response that are difficult to assess experimentally. In this narrative review, we highlight important mechanisms of IAV coinfection with bacterial and viral pathogens and survey mathematical models of coinfection and the insights gained from them. We discuss current challenges and limitations facing coinfection modeling, as well as current trends and future directions toward a complete understanding of coinfection using mathematical modeling and computer simulation.

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.

Interactions among acute respiratory viruses in Beijing, Chongqing, Guangzhou, and Shanghai, China, 2009-2019

Background

A viral infection can modify the risk to subsequent viral infections via cross-protective immunity, increased immunopathology, or disease-driven behavioral change. There is limited understanding of virus-virus interactions due to lack of long-term population-level data.

Methods

Our study leverages passive surveillance data of 10 human acute respiratory viruses from Beijing, Chongqing, Guangzhou, and Shanghai collected during 2009 to 2019: influenza A and B viruses; respiratory syncytial virus A and B; human parainfluenza virus (HPIV), adenovirus, metapneumovirus (HMPV), coronavirus, bocavirus (HBoV), and rhinovirus (HRV). We used a multivariate Bayesian hierarchical model to evaluate correlations in monthly prevalence of test-positive samples between virus pairs, adjusting for potential confounders.

Results

Of 101,643 lab-tested patients, 33,650 tested positive for any acute respiratory virus, and 4,113 were co-infected with multiple viruses. After adjusting for intrinsic seasonality, long-term trends and multiple comparisons, Bayesian multivariate modeling found positive correlations for HPIV/HRV in all cities and for HBoV/HRV and HBoV/HMPV in three cities. Models restricted to children further revealed statistically significant associations for another ten pairs in three of the four cities. In contrast, no consistent correlation across cities was found among adults. Most virus-virus interactions exhibited substantial spatial heterogeneity.

Conclusions

There was strong evidence for interactions among common respiratory viruses in highly populated urban settings. Consistent positive interactions across multiple cities were observed in viruses known to typically infect children. Future intervention programs such as development of combination vaccines may consider spatially consistent virus-virus interactions for more effective control.

Pathogenesis of an experimental coinfection of porcine parainfluenza virus 1 and influenza A virus in commercial nursery swine

Porcine parainfluenza virus 1 (PPIV-1) is a recently characterized swine respirovirus. Previous experimental studies reported PPIV-1 replicates in the porcine respiratory tract causing minimal clinical disease or lesions. However, it is unknown if PPIV-1 co-infections with viral respiratory pathogens would cause respiratory disease consistent with natural infections reported in the field. The objective of this study was to evaluate if PPIV-1 increases the severity of influenza A virus respiratory disease in swine. Fifty conventional, five-week-old pigs were assigned to one of three challenge groups (n = 15) or a negative control group (n = 5). Pigs were challenged with a γ-cluster H1N2 influenza A virus in swine (IAV-S; A/Swine/North Carolina/00169/2006), PPIV-1 (USA/MN25890NS/2016), inoculum that contained equivalent titers of IAV-S and PPIV-1 (CO-IN), or negative control. Clinical scores representing respiratory disease and nasal swabs were collected daily and all pigs were necropsied five days post inoculation (DPI). The CO-IN group demonstrated a significantly lower percentage of pigs showing respiratory clinical signs relative to the IAV-S challenge group from 2 to 4 DPI. The IAV-S and CO-IN groups had significantly lower microscopic composite lesion scores in the upper respiratory tract compared to the PPIV-1 group although the IAV-S and CO-IN groups had significantly higher microscopic composite lung lesion scores. Collectively, PPIV-1 did not appear to influence severity of clinical disease, macroscopic lesions, or alter viral loads detected in nasal swabs or necropsy tissues when administered as a coinfection with IAV-S. Studies evaluating PPIV-1 coinfections with different strains of IAV-S, different respiratory pathogens or sequential exposure of PPIV-1 and IAV-S are warranted.

Changes in Influenza Activities Impacted by NPI Based on 4-Year Surveillance in China: Epidemic Patterns and Trends

BACKGROUND

Since the Non-pharmaceutical Intervention (NPI) by COVID-19 emerged, influenza activity has been somewhat altered.

OBJECTIVES

The aim of this study was to explore changes in influenza activities in the context of COVID-19 based on the sentinel hospitals/units in Guangdong, southern China.

METHODS

The surveillance data in influenza-like illness (ILI) were collected from 21 cities in Guangdong between September 2017 and August 2021, while 43 hospitals/units were selected to analyze the predominant types of influenza, population characteristics, and seasonal features by three methods (the concentration ratio, the seasonal index, and the circulation distribution), based on a descriptive epidemiological approach.

RESULTS

During the four consecutive influenza seasons, a total of 157345 ILIs were tested, of which 9.05% were positive for influenza virus (n = 14238), with the highest positive rates for both IAV (13.20%) and IBV (5.41%) in the 2018-2019 season. After the emergence of COVID-19, influenza cases decreased near to zero from March 2020 till March 2021, and the dominant type of influenza virus changed from IAV to IBV. The highest positive rate of influenza existed in the age-group of 5 ~  < 15 years in each season for IAV (P < 0.001), which was consistent with that for IBV (P < 0.001). The highest annual positive rates for IBV emerged in eastern Guangdong, while the highest annual positive rates of IAV in different seasons existed in different regions. Furthermore, compared with the epidemic period (ranged from December to June) during 2017-2019, the period ended three months early (March 2020) in 2019-2020, and started by five months behind (April 2021) during 2020-2021.

CONCLUSION

The highest positive rates in 5 ~  < 15 age-group suggested the susceptible in this age-group mostly had infected with infected B/Victoria. Influenced by the emergence of COVID-19 and NPI responses, the epidemic patterns and trends of influenza activities have changed in Guangdong, 2017-2021.

Seasonal Prevalence of Respiratory Pathogens Among Children in the United Arab Emirates: A Multicenter Cross-Sectional Study in the Pre-COVID-19 Era

Background Viral respiratory infections in children pose a significant burden on healthcare facilities globally. In the United Arab Emirates (UAE) these account for 15% of all healthcare encounters among children. However, the seasonal prevalence and molecular epidemiology of respiratory viral infections in the UAE remains unknown. We sought to determine trends in seasonal viral prevalence in order to monitor disease activity and optimize the timing of Respiratory Syncytial Virus (RSV) prophylaxis among high-risk infants in the UAE. Methods This cross-sectional multicenter study included children 0-18 years of age who presented to a large private healthcare group in Dubai, UAE, and had upper respiratory samples collected for multiplex polymerase chain reaction (mPCR) testing between January 1st and December 31st, 2019. Sociodemographic, clinical, and molecular data were examined for children who tested positive for any pathogen on the mPCR panel. Results A total of three thousand and ninety-eight infants and children had mPCR assays performed during the study period, of which 2427 (78.3%) were positive for any respiratory pathogen. The median age of our sample population was 39 months and 56.8% were male. Emergency room was the most common site (34.7%) of sample collection and the vast majority of children presented with fever (85.3%). Rhinovirus/enterovirus was the most prevalent viral infection (45%) throughout the year and peaked in September, followed by Influenza (20.2%), and RSV (17.1%). RSV season, defined as an infection prevalence of >10%, occurred from August to December with a peak in October. Adenovirus (15.6%) infections peaked in June and accounted for 43% of hospitalizations in our study (p<0.05). Viral co-infections with RSV and rhinovirus/enterovirus were most common and observed in 19.9 % of children. Conclusion Rhinovirus/enterovirus is the most prevalent viral pathogen throughout the calendar year among the pediatric population in the UAE. RSV season begins earlier than reported in other countries regionally, hence RSV prophylaxis should be initiated in August to optimize protection among high-risk infants.

Temporal Shift of the Respiratory Syncytial Virus Epidemic Peak for the Years 2020-2023 in Marseille, Southern France

Respiratory syncytial virus is among the most common causes of respiratory infections. Typically, this viral infection has a seasonality during the cold months but with the SARS-CoV-2 pandemic this has been considerably modified. Here, we studied the epidemiology of this virus in university hospitals of Marseille, South of France, over the period 2020 to 2023. We tested in our laboratory from July 2020 to October 2021 16,516 nasopharyngeal swabs from 16,468 patients for RSV infection using different qPCR assays. We then analyzed data from previous and subsequent winters (from 2018 to 2023) and previous summers (from 2015 to 2021). A total of 676 patients were RSV-positive; their mean age was 3 years and 91 were under 5 years of age. We observed a delay of 4 months of the RSV epidemic's onset compared to other years with an epidemic that peaked in March 2021. We had significantly more RSV-positive cases during summer 2021 compared to previous summers, whereas the incidence of RSV infections was not significantly higher during winter 2022 versus previous winters. Moreover, 494 patients were diagnosed as RSV-positive in the emergency unit and 181 were subsequently hospitalized, and 34 patients were diagnosed RSV-positive while already in the intensive care unit. Over all the study periods, 38 patients diagnosed as RSV-positive died, the majority of whom (23/28) were over 65 years of age. These data show an atypical evolution of the incidence of RSV infections in our city and is another example of the unpredictability of infectious disease epidemiology.

Co-Infection Rates between SARS-CoV-2 and RSV in Oropharyngeal, Nasopharyngeal Aspirate and Saliva Samples of COVID-19 Patients, Shiraz, South of Iran

Statement of the Problem

Determining the prevalence of respiratory viruses' coinfection with coronavirus disease 2019 (COVID-19) is essential to defining its true clinical influence.

Purpose

This study aimed to evaluate co-infection rates between severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) in infected patients in Shiraz, south of Iran.

Materials and Method

In a cross-sectional descriptive study, oropharyngeal, nasopharyngeal aspirate (NPA), and saliva samples of 50 COVID-19 patients who were referred to Ali-Asghar hospital (Shiraz, Iran) from March to August 2020, were collected. A control group consisted of age and sex-matched healthy participants. The nasopharyngeal and oropharyngeal aspirates were collected by sterile swabs. All cases were hospitalized, and all SARS-CoV-2 patients had a fever and respiratory symptoms. The samples were packed in a vial with 1 mL of transport medium and transported to the Valfagre specialty laboratory, where they were tested for RSV using a real-time polymerase chain reaction (PCR).

Results

100 nasopharyngeal/oropharyngeal aspirates and saliva samples including 50 healthy controls (24 females, 26 males) and 50 COVID-19 patients' samples (27 males and 23 females) were studied. There was no significant difference regarding age as well as gender between both groups (p> 0.05). None of the healthy subjects was infected with RSV; however, 5(10%) patients from COVID-19 group were infected with the RSV virus. Chi-square test did not show a significant difference between RSV infection in COVID-19 patients and healthy subjects.

Conclusion

The outcome of present research showed that concurrent RSV with COVID 19 infection might be seen in hospitalized patients in Shiraz Southwest of Iran. For more reliable findings, further research on bigger populations, including more pathogens in several places around the country, and considering the severity of symptoms is required.

How Interactions during Viral-Viral Coinfection Can Shape Infection Kinetics

Respiratory viral infections are a leading global cause of disease with multiple viruses detected in 20-30% of cases, and several viruses simultaneously circulating. Some infections with unique viral copathogens result in reduced pathogenicity, while other viral pairings can worsen disease. The mechanisms driving these dichotomous outcomes are likely variable and have only begun to be examined in the laboratory and clinic. To better understand viral-viral coinfections and predict potential mechanisms that result in distinct disease outcomes, we first systematically fit mathematical models to viral load data from ferrets infected with respiratory syncytial virus (RSV), followed by influenza A virus (IAV) after 3 days. The results suggest that IAV reduced the rate of RSV production, while RSV reduced the rate of IAV infected cell clearance. We then explored the realm of possible dynamics for scenarios that had not been examined experimentally, including a different infection order, coinfection timing, interaction mechanisms, and viral pairings. IAV coinfection with rhinovirus (RV) or SARS-CoV-2 (CoV2) was examined by using human viral load data from single infections together with murine weight-loss data from IAV-RV, RV-IAV, and IAV-CoV2 coinfections to guide the interpretation of the model results. Similar to the results with RSV-IAV coinfection, this analysis shows that the increased disease severity observed during murine IAV-RV or IAV-CoV2 coinfection was likely due to the slower clearance of IAV-infected cells by the other viruses. The improved outcome when IAV followed RV, on the other hand, could be replicated when the rate of RV infected cell clearance was reduced by IAV. Simulating viral-viral coinfections in this way provides new insights about how viral-viral interactions can regulate disease severity during coinfection and yields testable hypotheses ripe for experimental evaluation.

A target-cell limited model can reproduce influenza infection dynamics in hosts with differing immune responses

We consider a hierarchy of ordinary differential equation models that describe the within-host viral kinetics of influenza infections: the IR model explicitly accounts for an immune response to the virus, while the simpler, target-cell limited TEIV and TV models do not. We show that when the IR model is fitted to pooled experimental murine data of the viral load, fraction of dead cells, and immune response levels, its parameters values can be determined. However, if, as is common, only viral load data are available, we can estimate parameters of the TEIV and TV models but not the IR model. These results are substantiated by a structural and practical identifiability analysis. We then use the IR model to generate synthetic data representing infections in hosts whose immune responses differ. We fit the TV model to these synthetic datasets and show that it can reproduce the characteristic exponential increase and decay of viral load generated by the IR model. Furthermore, the values of the fitted parameters of the TV model can be mapped from the immune response parameters in the IR model. We conclude that, if only viral load data are available, a simple target-cell limited model can reproduce influenza infection dynamics and distinguish between hosts with differing immune responses.

How Interactions During Viral-Viral Coinfection Can Shape Infection Kinetics

Respiratory virus infections are a leading cause of disease worldwide with multiple viruses detected in 20-30% of cases and several viruses simultaneously circulating. Some infections with viral copathogens have been shown to result in reduced pathogenicity while other virus pairings can worsen disease. The mechanisms driving these dichotomous outcomes are likely variable and have only begun to be examined in the laboratory and clinic. To better understand viral-viral coinfections and predict potential mechanisms that result in distinct disease outcomes, we first systematically fit mathematical models to viral load data from ferrets infected with respiratory syncytial virus (RSV) followed by influenza A virus (IAV) after 3 days. The results suggested that IAV reduced the rate of RSV production while RSV reduced the rate of IAV infected cell clearance. We then explored the realm of possible dynamics for scenarios not examined experimentally, including different infection order, coinfection timing, interaction mechanisms, and viral pairings. IAV coinfection with rhinovirus (RV) or SARS-CoV-2 (CoV2) was examined by using human viral load data from single infections together with murine weight loss data from IAV-RV, RV-IAV, and IAV-CoV2 coinfections to guide the interpretation of the model results. Similar to the results with RSV-IAV coinfection, this analysis showed that the increased disease severity observed during murine IAV-RV or IAV-CoV2 coinfection was likely due to slower clearance of IAV infected cells by the other viruses. On the contrary, the improved outcome when IAV followed RV could be replicated when the rate of RV infected cell clearance was reduced by IAV. Simulating viral-viral coinfections in this way provides new insights about how viral-viral interactions can regulate disease severity during coinfection and yields testable hypotheses ripe for experimental evaluation.

Viral loads of parainfluenza virus type 3 and severity of respiratory diseases in children

BACKGROUND

Parainfluenza virus type 3 (PIV-3) is one of the common pathogens for respiratory infections in children. Whether viral load of PIV-3 is associated with severity of respiratory diseases in children is not yet known. Our aim was to determine significance of PIV-3 viral load among infected children.

METHODS

We conducted a single-center, retrospective study at Tokyo Metropolitan. Children's Medical Center, Japan, from June to August 2021. Hospitalized children were screened with a posterior nasal swab for multiplex PCR, and viral load was subsequently measured from remained samples by real-time PCR. Demographic data were collected from digital charts. PIV-3 positive patients were categorized into mild group with no oxygen demand, moderate group with low-flow oxygen demand and severe group with high-flow nasal cannula oxygen or non-invasive positive pressure ventilation or mechanical ventilation. Viral loads were compared among mild, moderate and severe groups.

RESULTS

151 patients were positive for PIV-3. We found no statistically significant association among PIV-3 viral load and severity of respiratory diseases (p = 0.35), and no statistically significant association between severity of illness and co-detection of other viruses. In each severity group, relatively high viral load per posterior nasal swab was observed at the time of testing.

CONCLUSION

Among PIV-3 patients, we could not find statistically significant between viral load and their severity, therefore we could not conclude that viral load is a good surrogate marker for clinical severity of PIV-3.

Performance Evaluation of STANDARD Q COVID/FLU Ag Combo for Detection of SARS-CoV-2 and Influenza A/B

We evaluated the performance of the STANDARD Q COVID/FLU Ag Combo test (Q Ag combo test) for the detection of SARS-CoV-2, influenza A, and influenza B using a single point-of-care device compared with real-time PCR. A total of 408 individuals, 55 positives with SARS-CoV-2, 90 with influenza A, 68 with influenza B, and 195 negatives for all viruses, participated. The Q Ag combo test demonstrated a high level of sensitivity of 92.73% and a specificity of 99.49% for the detection of SARS-CoV-2. When the number of days from symptom onset (DSO) was restricted to 0 < DSO ≤ 6, the sensitivity of the Q Ag combo test to detect SARS-CoV-2 was 100%, and when the Ct value of RdRp was ≤20, the sensitivity to detect SARS-CoV-2 was 93.10%. The Q Ag combo test results also demonstrated a sensitivity of 92.22% and a specificity of 100% for influenza A, a sensitivity of 91.18%, and a specificity of 99.49% for influenza B. The agreement analysis of the Q Ag combo test with the RT-PCR results demonstrated excellent outcomes, making it useful and efficient for the detection of SARS-CoV-2, influenza A, and influenza B.

Respiratory Syncytial Virus Incidence and Severity in a Community-Based Prospective Cohort of Children Aged 0-14 Years

BACKGROUND

Respiratory syncytial virus (RSV) is a substantial source of severe illnesses including acute lower respiratory infections (ALRIs) like pneumonia. However, its burden in older children remains less well understood.

METHODS

Using a community-based prospective cohort, we assessed the burden of symptomatic reverse-transcription polymerase chain reaction-confirmed RSV among Nicaraguan children aged 0-14 years from 2011 to 2016. ALRI was defined as physician diagnosis of pneumonia, bronchiolitis, bronchitis, or bronchial hyperreactivity.

RESULTS

Between 2011 and 2016, 2575 children participated in the cohort. Of these, 630 (24.5%) had at least 1 episode of symptomatic RSV and 194 (7.5%) had multiple episodes. Subtype was identified in 571 (69.3%) episodes with 408 (71.5%) RSV-A, 157 (27.5%) RSV-B, and 6 (1%) positive for both. Children aged <2 years displayed the highest incidence of symptomatic RSV, with 269.3 cases per 1000 person-years (95% confidence interval [CI], 242.1-299.5). Beyond 2 years, incidence (95% CI) of symptomatic RSV decreased rapidly: 145.6 (129.9-163.1), 37.9 (31.9-45.0), and 19.3 (14.9-25.0) cases per 1000 person-years among children aged 2-4, 5-9, and 10-14 years, respectively. Incidence of RSV-associated ALRI was highest in children aged <2 years (85.95 per 1000 person-years [95% CI, 71.30-103.61]): 2.1, 9.5, and 17.3 times that of participants aged 2-4, 5-9, and 10-14 years, respectively. Children <2 years old were significantly more likely to have an RSV-associated hospitalization (P < .001).

CONCLUSIONS

There is a substantial burden of symptomatic and severe RSV in children. While older children did present with RSV, the rates of symptomatic and severe RSV decreased by as much as 95% beyond age 5.

Interactions Between Severe Acute Respiratory Syndrome Coronavirus 2 Replication and Major Respiratory Viruses in Human Nasal Epithelium

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), along with extensive nonpharmacological interventions, have profoundly altered the epidemiology of major respiratory viruses. Some studies have described virus-virus interactions, particularly manifested by viral interference mechanisms at different scales. However, our knowledge of the interactions between SARS-CoV-2 and other respiratory viruses remains incomplete. Here, we studied the interactions between SARS-CoV-2 and several respiratory viruses (influenza, respiratory syncytial virus, human metapneumovirus, and human rhinovirus) in a reconstituted human epithelial airway model, exploring different scenarios affecting the sequence and timing of coinfections. We show that the virus type and sequence of infections are key factors in virus-virus interactions, the primary infection having a determinant role in the immune response to the secondary infection.

The role of human bocavirus as an agent of community-acquired pneumonia in children under 5 years of age in Fortaleza, Ceará (Northeast Brazil)

The human bocavirus (HBoV) is an agent of upper and lower respiratory infections, affecting mainly children under 5 years of age. Community-acquired pneumonia (CAP) is an important public health problem in developing countries, representing one of the main causes of hospitalizations and deaths in children. The aim of this study was to describe the prevalence of HBoV and the clinical and epidemiological characteristics in children diagnosed with CAP. For this purpose, nasopharyngeal aspirates were collected from 545 children aged 0 to 60 months diagnosed with CAP between January 2013 and December 2014 in a reference pediatric hospital in Fortaleza, Ceará, Brazil. The samples were subjected to PCR for detection of HBoV and parainfluenza 4 (PIV4) and indirect immunofluorescence for detection of respiratory syncytial virus (RSV), adenovirus (AdV), influenza A and B (FLU A and FLU B), and parainfluenza 1, 2, and 3 (PIV1, PIV2, PIV3). Clinically, most CAP were non-complicated (487/545; 89.3%); however, 10.7% (58/545) of children were treated in the ICU/resuscitation sector. Among the total samples analyzed, 359 (65.8%) were positive for at least one virus surveyed and 105 (19.2%) samples had two or more viruses. HBoV was detected in 87 samples (15.9%), being the second most prevalent virus. RSV, AdV, FLU A, FLU B, and PIV 1-3 were detected in 150 (27.5%), 45 (8.2%), 30 (5.5%), 3 (0.5%), and 131 (24%) samples, respectively. The age average was 12.1 months in children infected with HBoV, and the most frequent symptoms were dyspnea and cough. In addition, 90.6% of HboV-positive children received antibiotics as empirical treatment. HBoV did not show any circulation pattern; however, it seemed to be more frequent in the first half of the year, totaling 68.9% of the cases. HBoV is a frequent agent of pneumonia in the child population studied.

Interference between rhinovirus and other RNA respiratory viruses in the first 2-years of life: A longitudinal community-based birth cohort study

BACKGROUND

Cross-sectional studies report negative associations between rhinovirus and other RNA respiratory viruses. However, longitudinal studies with frequent, serial sampling are needed to identify the directionality of this relationship and its nature.

OBJECTIVE

To investigate the association between rhinovirus and other RNA respiratory viruses detected 1-week apart.

METHODS

The Observational Research in Childhood Infectious Diseases cohort study was conducted in Brisbane, Australia (2010-2014). Parents collected nasal swabs weekly from birth until age 2-years. Swabs were analysed by real-time polymerase chain reaction. The association between new rhinovirus detections and five other RNA viruses (influenza, respiratory syncytial virus, parainfluenza viruses, seasonal human coronaviruses, and human metapneumovirus) in paired swabs 1-week apart were investigated.

RESULTS

Overall, 157 children provided 8,101 swabs, from which 4,672 paired swabs 1-week apart were analysed. New rhinovirus detections were negatively associated with new pooled RNA respiratory virus detections 1-week later (adjusted odds ratio (aOR) 0.48; 95% confidence interval (CI): 0.13-0.83), as were pooled RNA virus detections with new rhinovirus detections the following week (aOR 0.34; 95%CI: 0.09-0.60). At the individual species level, rhinovirus had the strongest negative association with new seasonal human coronavirus detections in the subsequent week (aOR 0.34; 95%CI: 0.120.95) and respiratory syncytial virus had the strongest negative association with rhinovirus 1-week later (aOR 0.21; 95%CI: 0.050.88).

CONCLUSION

A strong, negative bidirectional association was observed between rhinovirus and other RNA viruses in a longitudinal study of a community-based cohort of young Australian children. This suggests within-host interference between RNA respiratory viruses.

Epidemiology of a major honey bee pathogen, deformed wing virus: potential worldwide replacement of genotype A by genotype B

The western honey bee (Apis mellifera) is of major economic and ecological importance, with elevated rates of colony losses in temperate regions over the last two decades thought to be largely caused by the exotic ectoparasitic mite Varroa destructor and deformed wing virus (DWV), which the mite transmits. DWV currently exists as two main genotypes: the formerly widespread DWV-A and the more recently described and rapidly expanding DWV-B. It is an excellent system to understand viral evolution and the replacement of one viral variant by another. Here we synthesise published results on the distribution and prevalence of DWV-A and -B over the period 2008-2021 and present novel data for Germany, Italy and the UK to suggest that (i) DWV-B has rapidly expanded worldwide since its first description in 2004 and (ii) that it is potentially replacing DWV-A. Both genotypes are also found in wild bee species. Based on a simple mathematical model, we suggest that interference between viral genotypes when co-infecting the same host is key to understanding their epidemiology. We finally discuss the consequences of genotype replacement for beekeeping and for wild pollinator species.

Viral etiology among children hospitalized for acute respiratory tract infections and its association with meteorological factors and air pollutants: a time-series study (2014-2017) in Macao

Background

The associations between viral etiology of acute respiratory infections (ARI) with meteorological factors and air pollutants among children is not fully understood. This study aimed to explore the viral etiology among children hospitalized for ARI and the association of meteorological factors and air pollutants with children hospitalization due to viral ARI.

Methods

Electronic health record data about children (aged between 1 month and 14 years) admitted for ARI at Kiang Wu Hospital in Macao between 2014 and 2017 was analyzed retrospectively. xMAP multiplex assays were used to detect viruses in the nasopharyngeal swab and distributed-lag nonlinear model (DLNM) was used to evaluate associations.

Results

Among the 4880 cases of children hospitalization due to ARI, 3767 (77.2%) were tested positive for at least one virus and 676 (18%) exhibited multiple infections. Enterovirus (EV)/rhinovirus (HRV), adenovirus (ADV), respiratory syncytial virus (RSV) and influenza virus (IFV) were the most common viral pathogens associated with ARI and human bocavirus (hBOV) exhibited the highest multiple infection rates. Meteorological factors and air pollutants (PM₁₀, PM_2.5 and NO₂) were associated with the risk of viral ARI hospitalization. The relative risk of viral infection increased with daily mean temperature but plateaued when temperature exceeded 23 °C, and increased when the relative humidity was < 70% and peaked at 50%. The effect of solar radiation was insignificant. Air pollutants (including PM₁₀, PM_2.5, NO₂ and O₃) showed strong and immediate effect on the incidence of viral infection.

Conclusions

The effects of mean temperature, relative humidity and air pollutants should be taken into account when considering management of ARI among children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07585-y.

Analysis of severe human adenovirus infection outbreak in Guangdong Province, southern China in 2019

During 2018-2019, a severe human adenovirus (HAdV) infection outbreak occurred in southern China. Here, we screened 18 respiratory pathogens in 1704 children (≤ 14 years old) hospitalized with acute respiratory illness in Guangzhou, China, in 2019. In total, 151 patients had positive HAdV test results; 34.4% (52/151) of them exhibited severe illness. HAdV infection occurred throughout the year, with a peak in summer. The median patient age was 3.0 (interquartile range: 1.1-5.0) years. Patients with severe HAdV infection exhibited increases in 12 clinical indexes (P ​≤ ​0.019) and decreases in four indexes (P ​≤ ​0.007), compared with patients exhibiting non-severe infection. No significant differences were found in age or sex distribution according to HAdV infection severity (P ​> ​0.05); however, the distributions of comorbid disease and HAdV co-infection differed according to HAdV infection severity (P ​< ​0.05). The main epidemic types were HAdV-3 (47.0%, 71/151) and HAdV-7 (46.4%, 70/151). However, the severe illness rate was significantly higher in patients with HAdV-7 (51.4%) than in patients with HAdV-3 (19.7%) and other types of HAdV (20%) (P ​< ​0.001). Sequencing analysis of genomes/capsid genes of 13 HAdV-7 isolates revealed high similarity to previous Chinese isolates. A representative HAdV-7 isolate exhibited a similar proliferation curve to the curve described for the epidemic HAdV-3 strain Guangzhou01 (accession no. DQ099432) (P ​> ​0.05); the HAdV-7 isolate exhibited stronger virulence and infectivity, compared with HAdV-3 (P ​< ​0.001). Overall, comorbid disease, HAdV co-infection, and high virulence and infectivity of HAdV-7 were critical risk factors for severe HAdV infection; these data can facilitate treatment, control, and prevention of HAdV infection.

Design, optimization, and application of multiplex rRT-PCR in the detection of respiratory viruses

Viral respiratory infections are common and serious diseases. Because there is no effective treatment method or vaccine for respiratory tract infection, early diagnosis is vital to identify the pathogen so as to determine the infectivity of the patient and to quickly take measures to curb the spread of the virus, if warranted, to avoid serious public health problems. Real-time reverse transcriptase PCR (rRT-PCR), which has high sensitivity and specificity, is the best approach for early diagnosis. Among rRT-PCR methods, multiplex rRT-PCR can resolve issues arising from various types of viruses, high mutation frequency, coinfection, and low concentrations of virus. However, the design, optimization, and validation of multiplex rRT-PCR are more complicated than singleplex rRT-PCR, and comprehensive research on multiplex rRT-PCR methodology is lacking. This review summarizes recent progress in multiplex rRT-PCR methodology, outlines the principles of design, optimization and validation, and describes a scheme to help diagnostic companies to design and optimize their multiplex rRT-PCR detection panel and to assist laboratory staff to solve problems in their daily work. In addition, the analytical validity, clinical validity and clinical utility of multiplex rRT-PCR in viral respiratory tract infection diagnosis are assessed to provide theoretical guidance and useful information for physicians to understand the test results.

Detection of SARS-CoV-2 antibodies in febrile patients from an endemic region of dengue and chikungunya in Peru

Introduction

The rapid expansion of the novel SARS-CoV-2 virus has raised serious public health concerns due to the possibility of misdiagnosis in regions where arboviral diseases are endemic. We performed the first study in northern Peru to describe the detection of SARS-CoV-2 IgM antibodies in febrile patients with a suspected diagnosis of dengue and chikungunya fever.

Materials and methods

A consecutive cross-sectional study was performed in febrile patients attending primary healthcare centers from April 2020 through March 2021. Patients enrolled underwent serum sample collection for the molecular and serological detection of DENV and CHIKV. Also, serological detection of IgM antibodies against SARS-CoV-2 was performed.

Results

464 patients were included during the study period, of which (40.51%) were positive for one pathogen, meanwhile (6.90%) presented co-infections between 2 or more pathogens. The majority of patients with monoinfections were positive for SARS-CoV-2 IgM with (73.40%), followed by DENV 18.09% and CHIKV (8.51%). The most frequent co-infection was DENV + SARS-CoV-2 with (65.63%), followed by DENV + CHIKV and DENV + CHIKV + SARS-CoV-2, both with (12.50%). The presence of polyarthralgias in hands (43.75%, p<0.01) and feet (31.25%, p = 0.05) were more frequently reported in patients with CHIKV monoinfection. Also, conjunctivitis was more common in patients positive for SARS-CoV-2 IgM (11.45%, p<0.01). The rest of the symptoms were similar among all the study groups.

Conclusion

SARS-CoV-2 IgM antibodies were frequently detected in acute sera from febrile patients with a clinical suspicion of arboviral disease. The presence of polyarthralgias in hands and feet may be suggestive of CHIKV infection. These results reaffirm the need to consider SARS-CoV-2 infection as a main differential diagnosis of acute febrile illness in arboviruses endemic areas, as well as to consider co-infections between these pathogens.

Contribution of Influenza Viruses, Other Respiratory Viruses and Viral Co-Infections to Influenza-like Illness in Older Adults

Influenza-like illness (ILI) can be caused by a range of respiratory viruses. The present study investigates the contribution of influenza and other respiratory viruses, the occurrence of viral co-infections, and the persistence of the viruses after ILI onset in older adults. During the influenza season 2014–2015, 2366 generally healthy community-dwelling older adults (≥60 years) were enrolled in the study. Viruses were identified by multiplex ligation–dependent probe-amplification assay in naso- and oropharyngeal swabs taken during acute ILI phase, and 2 and 8 weeks later. The ILI incidence was 10.7%, which did not differ between vaccinated and unvaccinated older adults; influenza virus was the most frequently detected virus (39.4%). Other viruses with significant contribution were: rhinovirus (17.3%), seasonal coronavirus (9.8%), respiratory syncytial virus (6.7%), and human metapneumovirus (6.3%). Co-infections of influenza virus with other viruses were rare. The frequency of ILI cases in older adults in this 2014–2015 season with low vaccine effectiveness was comparable to that of the 2012–2013 season with moderate vaccine efficacy. The low rate of viral co-infections observed, especially for influenza virus, suggests that influenza virus infection reduces the risk of simultaneous infection with other viruses. Viral persistence or viral co-infections did not affect the clinical outcome of ILI.

SARS-CoV-2 and Influenza Viruses: Strategies to Cope with Co-infection and Bioinformatics Perspective

Almost a century after the devastating pandemic of the Spanish flu, humankind is facing the relatively comparable global outbreak of COVID‐19. COVID‐19 is an infectious disease caused by SARS‐CoV‐2 with an unprecedented transmission pattern. In the face of the recent repercussions of COVID‐19, many have argued that the clinical experience with influenza through the last century may have tremendous implications in the containment of this newly emerged viral disease. During the last 2 years, from the emergence of COVID‐19, tremendous advances have been made in diagnosing and treating coinfections. Several approved vaccines are available now for the primary prevention of COVID‐19 and specific treatments exist to alleviate symptoms. The present review article aims to discuss the pathophysiology, diagnosis, and treatment of SARS‐CoV‐2 and influenza A virus coinfection while delivering a bioinformatics‐based insight into this subject matter.

Treatment of Respiratory Viral Coinfections

With the advent of rapid multiplex PCR, physicians have been able to test for multiple viral pathogens when a patient presents with influenza-like illness. This has led to the discovery that many respiratory infections are caused by more than one virus. Antiviral treatment of viral coinfections can be complex because treatment of one virus will affect the time course of the other virus. Since effective antivirals are only available for some respiratory viruses, careful consideration needs to be given on the effect treating one virus will have on the dynamics of the other virus, which might not have available antiviral treatment. In this study, we use mathematical models of viral coinfections to assess the effect of antiviral treatment on coinfections. We examine the effect of the mechanism of action, relative growth rates of the viruses, and the assumptions underlying the interaction of the viruses. We find that high antiviral efficacy is needed to suppress both infections. If high doses of both antivirals are not achieved, then we run the risk of lengthening the duration of coinfection or even of allowing a suppressed virus to replicate to higher viral titers.

Respiratory Syncytial Virus Infections in Young Children Presenting to Primary Care in Catalonia During the COVID-19 Pandemic

We observed an unusual pattern of respiratory syncytial virus (RSV) in children under 5 years in Catalonia (Spain). We observed a near absence of RSV during winter months and a subsequent surge during the late spring. Primary care electronic health records combined with hospital RSV laboratory confirmation could be used to monitor trends of respiratory pathogens.

Influenza A(H1N1)pdm09 Virus but Not Respiratory Syncytial Virus Interferes with SARS-CoV-2 Replication during Sequential Infections in Human Nasal Epithelial Cells

The types of interactions between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory viruses are not well-characterized due to the low number of co-infection cases described since the onset of the pandemic. We have evaluated the interactions between SARS-CoV-2 (D614G mutant) and influenza A(H1N1)pdm09 or respiratory syncytial virus (RSV) in the nasal human airway epithelium (HAE) infected simultaneously or sequentially (24 h apart) with virus combinations. The replication kinetics of each virus were determined by RT-qPCR at different post-infection times. Our results showed that during simultaneous infection, SARS-CoV-2 interferes with RSV-A2 but not with A(H1N1)pdm09 replication. The prior infection of nasal HAE with SARS-CoV-2 reduces the replication kinetics of both respiratory viruses. SARS-CoV-2 replication is decreased by a prior infection with A(H1N1)pdm09 but not with RSV-A2. The pretreatment of nasal HAE with BX795, a TANK-binding kinase 1 inhibitor, partially alleviates the reduced replication of SARS-CoV-2 or influenza A(H1N1)pdm09 during sequential infection with both virus combinations. Thus, a prior infection of nasal HAE with SARS-CoV-2 interferes with the replication kinetics of A(H1N1)pdm09 and RSV-A2, whereas only A(H1N1)pdm09 reduces the subsequent infection with SARS-CoV-2. The mechanism involved in the viral interference between SARS-CoV-2 and A(H1N1)pdm09 is mediated by the production of interferon.

Temporal and Gene Reassortment Analysis of Influenza C Virus Outbreaks in Hong Kong, SAR, China

From 2014 to week 07/2020 the Centre for Health Protection in Hong Kong conducted screening for influenza C virus (ICV). A retrospective analysis of ICV detections to week 26/2019 revealed persistent low-level circulation with outbreaks occurring biennially in the winters of 2015 to 2016 and 2017 to 2018 (R. S. Daniels et al., J Virol 94:e01051-20, 2020, https://doi.org/10.1128/JVI.01051-20). Here, we report on an outbreak occurring in 2019 to 2020, reinforcing the observation of biennial seasonality in Hong Kong. All three outbreaks occurred in similar time frames, were subsequently dwarfed by seasonal epidemics of influenza types A and B, and were caused by similar proportions of C/Kanagawa/1/76 (K)-lineage and C/São Paulo/378/82 S1- and S2-sublineage viruses. Ongoing genetic drift was observed in all genes, with some evidence of amino acid substitution in the hemagglutinin-esterase-fusion (HEF) glycoprotein possibly associated with antigenic drift. A total of 61 ICV genomes covering the three outbreaks were analyzed for reassortment, and 9 different reassortant constellations were identified, 1 K-lineage, 4 S1-sublineage, and 4 S2-sublineage, with 6 of these being identified first in the 2019-1920 outbreak (2 S2-lineage and 4 S1-lineage). The roles that virus interference/enhancement, ICV persistent infection, genome evolution, and reassortment might play in the observed seasonality of ICV in Hong Kong are discussed. IMPORTANCE Influenza C virus (ICV) infection of humans is common, with the great majority of people being infected during childhood, though reinfection can occur throughout life. While infection normally results in "cold-like" symptoms, severe disease cases have been reported in recent years. However, knowledge of ICV is limited due to poor systematic surveillance and an inability to propagate the virus in large amounts in the laboratory. Following recent systematic surveillance in Hong Kong SAR, China, and direct ICV gene sequencing from clinical specimens, a 2-year cycle of disease outbreaks (epidemics) has been identified, with gene mixing playing a significant role in ICV evolution. Studies like those reported here are key to developing an understanding of the impact of influenza C virus infection in humans, notably where comorbidities exist and severe respiratory disease can develop.

Interactions among 17 respiratory pathogens: a cross-sectional study using clinical and community surveillance data

Background

Co-circulating respiratory pathogens can interfere with or promote each other, leading to important effects on disease epidemiology. Estimating the magnitude of pathogen-pathogen interactions from clinical specimens is challenging because sampling from symptomatic individuals can create biased estimates.

Methods

We conducted an observational, cross-sectional study using samples collected by the Seattle Flu Study between 11 November 2018 and 20 August 2021. Samples that tested positive via RT-qPCR for at least one of 17 potential respiratory pathogens were included in this study. Semi-quantitative cycle threshold (Ct) values were used to measure pathogen load. Differences in pathogen load between monoinfected and coinfected samples were assessed using linear regression adjusting for age, season, and recruitment channel.

Results

21,686 samples were positive for at least one potential pathogen. Most prevalent were rhinovirus (33·5%), Streptococcus pneumoniae (SPn, 29·0%), SARS-CoV-2 (13.8%) and influenza A/H1N1 (9·6%). 140 potential pathogen pairs were included for analysis, and 56 (40%) pairs yielded significant Ct differences (p < 0.01) between monoinfected and co-infected samples. We observed no virus-virus pairs showing evidence of significant facilitating interactions, and found significant viral load decrease among 37 of 108 (34%) assessed pairs. Samples positive with SPn and a virus were consistently associated with increased SPn load.

Conclusions

Viral load data can be used to overcome sampling bias in studies of pathogen-pathogen interactions. When applied to respiratory pathogens, we found evidence of viral-SPn facilitation and several examples of viral-viral interference. Multipathogen surveillance is a cost-efficient data collection approach, with added clinical and epidemiological informational value over single-pathogen testing, but requires careful analysis to mitigate selection bias.

SARS-coronavirus-2 infections: biological instabilities characterized by order parameters

A four-variable virus dynamics TIIV model was considered that involves infected cells in an eclipse phase. The state space description of the model was transferred into an amplitude space description which is the appropriate general, nonlinear physics framework to describe instabilities. In this context, the unstable eigenvector or order parameter of the model was determined. Subsequently, a model-based analysis of viral load data from eight symptomatic COVID-19 patients was conducted. For all patients, it was found that the initial SARS-CoV-2 infection evolved along the respective patient-specific order parameter, as expected by theoretical considerations. The order parameter amplitude that described the initial virus multiplication showed doubling times between 30 minutes and 3 hours. Peak viral loads of patients were linearly related to the amplitudes of the patient order parameters. Finally, it was found that the patient order parameters determined qualitatively and quantitatively the relationships between the increases in virus-producing infected cells and infected cells in the eclipse phase. Overall, the study echoes the 40 years old suggestion by Mackey and Glass to consider diseases as instabilities.

Respiratory Syncytial Virus Provides Protection against a Subsequent Influenza A Virus Infection

Respiratory infections are a leading cause of morbidity and mortality. The presence of multiple heterologous virus infections is routinely observed in a subset of individuals screened for the presence of respiratory viruses. However, the impact overlapping infections has on disease severity and the host immune response is not well understood. Respiratory syncytial virus (RSV) and influenza A virus (IAV) are two of the most common respiratory infections observed in hospitalized patients, particularly in the very young and aged populations. In this study, we examined how the order in which BALB/c mice were infected with both RSV and IAV impacts disease severity. RSV infection prior to an IAV infection was associated with decreased weight loss and increased survival as compared with IAV infection alone. In contrast, IAV infection prior to an RSV infection was associated with similar morbidity and mortality as compared with an IAV infection alone. Our results suggest that the order in which viral infections are acquired plays a critical role in the outcome of disease severity and the host immune response.

Nasopharyngeal virome analysis of COVID-19 patients during three different waves in Campania region of Italy

From December 2019, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection has spread rapidly, leading to a global pandemic. Little is known about possible relationships between SARS‐CoV‐2 and other viruses in the respiratory system affecting patient prognosis and outcomes. This study aims to characterize respiratory virome profiles in association with SARS‐CoV‐2 infection and disease severity, through the analysis in 89 nasopharyngeal swabs collected in a patient's cohort from the Campania region (Southern Italy). Results show coinfections with viral species belonging to Coronaviridae, Retroviridae, Herpesviridae, Poxviridae, Pneumoviridae, Pandoraviridae, and Anelloviridae families and only 2% of the cases (2/89) identified respiratory viruses.

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The severe acute respiratory syndrome coronavirus 2 infection is considered a major global threat that is still spreading around the world.

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Nasopharyngeal swabs samples were collected from the Campania region cohort of 89 Covid‐19 patients.

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Descriptive analysis of respiratory virome was carried out with the HOME‐BIO pipeline, that performed viral taxonomy profiling.

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It detected coinfections with viral species belonging to Coronaviridae, Retroviridae, Herpesviridae, Poxviridae, Pneumoviridae, Pandoraviridae, and Anelloviridae family.

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Only 2% of the cases (2/89) identified respiratory viruses.

SARS-CoV-2 infection in children in Moscow in 2020: clinical features and impact on circulation of other respiratory viruses: SARS-CoV-2 infection in children in Moscow in 2020

Objectives

This study aimed to estimate the impact of the COVID-19 pandemic on the circulation of non-SARS-CoV-2 respiratory viruses and the clinical characteristics of COVID-19 in hospitalized children.

Methods

A total of 226 and 864 children admitted to the Children's City Clinical Hospital with acute respiratory infection in September to November of 2018 and 2020 in Moscow were tested for respiratory viruses using multiplex polymerase chain reaction (PCR) and Mycoplasma pneumoniae/Chlamydia pneumoniae using enzyme-linked immunosorbent assay.

Results

The detection rate of non-SARS-CoV-2 viruses in 2020 was lower than in 2018, 16.9% versus 37.6%. An increase in the median age of children with respiratory viruses was observed during the pandemic (3 years vs 1 year). There was no significant difference in the frequency of intensive care unit (ICU) admission in children with SARS-CoV-2 and other respiratory virus infections (2.7% vs 2.9%). SARS-CoV-2 and human rhinoviruses, human metapneumoviruses, and human adenoviruses showed significantly lower than expected co-detection rates during co-circulation. An increase in body mass index (BMI) or bacterial coinfection leads to an increased risk of ICU admission and a longer duration of COVID-19 in children.

Conclusions

The COVID-19 pandemic led to significant changes in the epidemiological characteristics of non-SARS-CoV-2 respiratory viruses during the autumn peak of the 2020 pandemic, compared with the same period in 2018.

Impact of Coinfection With SARS-CoV-2 and Influenza on Disease Severity: A Systematic Review and Meta-Analysis

Background: Although coinfection with influenza in COVID-19 patients has drawn considerable attention, it is still not completely understood whether simultaneously infected with these two viruses influences disease severity. We therefore aimed to estimate the impact of coinfected with SARS-CoV-2 and influenza on the disease outcomes compared with the single infection of SARS-CoV-2. Materials and Methods: We searched the PubMed, Web of Science, Embase, Cochrane Library, China National Knowledge Infrastructure Database (CNKI) to identify relevant articles up to July 9, 2021. Studies that assessed the effect of SARS-CoV-2 and influenza coinfection on disease outcomes or those with sufficient data to calculate risk factors were included. Risk effects were pooled using fixed or random effects model. Results: We ultimately identified 12 studies with 9,498 patients to evaluate the risk effects of SARS-CoV-2 and influenza coinfection on disease severity. Results indicated that coinfection was not significantly associated with mortality (OR = 0.85, 95%CI: 0.51, 1.43; p = 0.55, I ² = 76.00%). However, mortality was found significantly decreased in the studies from China (OR = 0.51, 95%CI: 0.39, 0.68; I ² = 26.50%), while significantly increased outside China (OR = 1.56, 95%CI: 1.12, 2.19; I ² = 1.00%). Moreover, a lower risk for critical outcomes was detected among coinfection patients (OR = 0.64, 95%CI: 0.43, 0.97; p = 0.04, I ² = 0.00%). Additionally, coinfection patients presented different laboratory indexes compared with the single SARS-CoV-2 infection, including lymphocyte counts and APTT. Conclusion: Our study revealed that coinfection with SARS-CoV-2 and influenza had no effect on overall mortality. However, risk for critical outcomes was lower in coinfection patients and different associations were detected in the studies from different regions and specific laboratory indexes. Further studies on influenza strains and the order of infection were warranted. Systematic testing for influenza coinfection in COVID-19 patients and influenza vaccination should be recommended.

SARS-CoV-2 and Influenza A virus Co-infections in Ferrets

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and seasonal influenza viruses are co-circulating in the human population. However, only a few cases of viral co-infection with these two viruses have been documented in humans with some people having severe disease and others mild disease. In order to examine this phenomenon, ferrets were co-infected with SARS-CoV-2 and human seasonal influenza A viruses (IAVs) (H1N1 or H3N2) and were compared to animals that received each virus alone. Ferrets were either immunologically naïve to both viruses or vaccinated with the 2019-2020 split-inactivated influenza virus vaccine. Co-infected naive ferrets lost significantly more body weight than ferrets infected with each virus alone and induced more severe inflammation in both the nose and lungs than ferrets single-infected with each virus. Co-infected naïve animals had predominantly higher IAV titers than SARS-CoV-2 titers, and IAVs efficiently transmitted to the co-housed ferrets by direct contact. Comparatively, SARS-CoV-2 failed to transmit to the ferrets that co-housed with co-infected ferrets by direct contact. Moreover, vaccination significantly reduced IAVs virus titers and shortened the viral shedding, but did not completely block influenza virus direct contact transmission. Notably, vaccination significantly ameliorated the influenza associated disease by protecting vaccinated animals from severe morbidity after IAV single infection or IAV and SARS-CoV-2 co-infection, suggesting that seasonal influenza virus vaccination is pivotal to prevent severe disease induced by IAVs and SARS-CoV-2 co-infection during the COVID-19 pandemic.

Importance

Influenza A viruses cause severe morbidity and mortality during each influenza virus season. The emergence of SARS-CoV-2 infection in the human population offers the opportunity to potential co-infections of both viruses. The development of useful animal models to asses pathogenesis, transmission, and viral evolution of these viruses as the co-infect a host is of critical importance for the development of vaccines and therapeutics. The ability to prevent the most severe effects of viral co-infections can be studied using effect co-infection ferret models described in this report.

Seasonal shedding patterns of diverse henipavirus-related paramyxoviruses in Egyptian rousette bats

Bat-borne viruses in the Henipavirus genus have been associated with zoonotic diseases of high morbidity and mortality in Asia and Australia. In Africa, the Egyptian rousette bat species (Rousettus aegyptiacus) is an important viral host in which Henipavirus-related viral sequences have previously been identified. We expanded these findings by assessing the viral dynamics in a southern African bat population. A longitudinal study of henipavirus diversity and excretion dynamics identified 18 putative viral species circulating in a local population, three with differing seasonal dynamics, and the winter and spring periods posing a higher risk of virus spillover and transmission. The annual peaks in virus excretion are most likely driven by subadults and may be linked to the waning of maternal immunity and recolonization of the roost in early spring. These results provide insightful information into the bat-host relationship that can be extrapolated to other populations across Africa and be communicated to at-risk communities as a part of evidence-based public health education and prevention measures against pathogen spillover threats.