Global patterns and drivers of influenza decline during the COVID-19 pandemic

Excess mortality during the first 2 years of the COVID-19 pandemic (2020-2021) in the Netherlands: Overall and across demographic subgroups

Objectives

The overall impact of the COVID-19 pandemic on mortality can be estimated by the assessment of excess deaths from all causes because the reported number of deaths due to COVID-19 do not accurately reflect the true death toll. We assessed excess mortality in 2020 and 2021 in the Netherlands.

Methods

All analyses were performed on data from comprehensive nationwide registers provided by Statistics Netherlands (Centraal Bureau voor de Statistiek), including demographic characteristics and mortality. All-cause mortality incidence rates were calculated per calendar month and compared against COVID-19 infections and preventive strategies. The all-cause mortality incidence rate ratios (IRRs) with 95% confidence intervals (95% CIs) were estimated per calendar year using Poisson regression (overall and for subgroups).

Results

Compared with predicted mortality based on 2019 rates, the overall excess mortality was 8.9% (IRR 1.089, 95% CI 1.081-1.097) in 2020 and 8.5% (IRR 1.085, 95% CI 1.077-1.092) in 2021. Relative excess mortality was higher for men, people with low household income, first-generation immigrants, and individuals living in extremely urbanized areas. In 2020, excess mortality was highest in age groups above 75 years (over 10%.); in 2021, it was clearly present even in the 20-39 years age group (6.6%).

Conclusions

Our results quantify excess mortality during the first 2 years of the COVID-19 pandemic in the Netherlands. We show that the extent of excess mortality varies considerably across demographic groups, which may help in identifying target groups for preventive strategies during future health crises.

Disruption of seasonal influenza circulation and evolution during the 2009 H1N1 and COVID-19 pandemics in Southeastern Asia

East, South, and Southeast Asia (together referred to as Southeastern Asia hereafter) have been recognized as critical areas fuelling the global circulation of seasonal influenza. However, the seasonal influenza migration network within Southeastern Asia remains unclear, including how pandemic-related disruptions altered this network. We leveraged genetic, epidemiological, and airline travel data between 2007-2023 to characterise the dispersal patterns of influenza A/H3N2 and B/Victoria viruses both out of and within Southeastern Asia, including during perturbations by the 2009 A/H1N1 and COVID-19 pandemics. During the COVID-19 pandemic, consistent autumn-winter movement waves from Southeastern Asia to temperate regions were interrupted for both subtype/lineages, however the A/H1N1 pandemic only disrupted A/H3N2 spread. We find a higher persistence of A/H3N2 than B/Victoria circulation in Southeastern Asia and identify distinct pandemic-related disruptions in A/H3N2 antigenic evolution between two pandemics, compared to interpandemic levels; similar patterns are observed in B/Victoria using genetic distance. The internal movement structure within Southeastern Asia markedly diverged during the COVID-19 pandemic season, and to a lesser extent, during the 2009 A/H1N1 pandemic season. Our findings provide insights into the heterogeneous impact of two distinct pandemic-related disruptions on influenza circulation, which can help anticipate the effects of future pandemics and potential mitigation strategies on influenza dynamics.

Integrating dynamical modeling and phylogeographic inference to characterize global influenza circulation

Global seasonal influenza circulation involves a complex interplay between local (seasonality, demography, host immunity) and global factors (international mobility) shaping recurrent epidemic patterns. No studies so far have reconciled the two spatial levels, evaluating the coupling between national epidemics, considering heterogeneous coverage of epidemiological, and virological data, integrating different data sources. We propose a novel-combined approach based on a dynamical model of global influenza spread (GLEAM), integrating high-resolution demographic, and mobility data, and a generalized linear model of phylogeographic diffusion that accounts for time-varying migration rates. Seasonal migration fluxes across countries simulated with GLEAM are tested as phylogeographic predictors to provide model validation and calibration based on genetic data. Seasonal fluxes obtained with a specific transmissibility peak time and recurrent travel outperformed the raw air-transportation predictor, previously considered as optimal indicator of global influenza migration. Influenza A subtypes supported autumn-winter reproductive number as high as 2.25 and an average immunity duration of 2 years. Similar dynamics were preferred by influenza B lineages, with a lower autumn-winter reproductive number. Comparing simulated epidemic profiles against FluNet data offered comparatively limited resolution power. The multiscale approach enables model selection yielding a novel computational framework for describing global influenza dynamics at different scales-local transmission and national epidemics vs. international coupling through mobility and imported cases. Our findings have important implications to improve preparedness against seasonal influenza epidemics. The approach can be generalized to other epidemic contexts, such as emerging disease outbreaks to improve the flexibility and predictive power of modeling.

Analysis of the incidence of influenza before and after the COVID-19 pandemic in South Korea

OBJECTIVES

Influenza outbreaks of varying size occur every year, but during the COVID-19 pandemic, many countries experienced influenza at lower levels. However, following the relaxation of COVID-19 prevention measures in 2022, the incidence of influenza began to increase gradually. Thus, this study compared the occurrence of influenza from week 36 of 2017, before the COVID-19 outbreak, until 2023.

METHODS

The analysis was conducted using influenza-like illness occurrence data available from the Korea Disease Control and Prevention Agency infectious disease website. Additionally, to examine the changes in COVID-19 and influenza occurrence during the pandemic, COVID-19 incidence data from 20 January 2020 to 31 August 2023 were obtained from the KDCA Coronavirus Disease 19 homepage.

RESULTS

During the COVID-19 pandemic, which corresponds to the 2020/2021 and 2021/2022 influenza seasons, there was no seasonal influenza epidemic, and the incidence rates were below the usual outbreak levels. However, in the 2022/2023 season, when the spread of COVID-19 had eased, a seasonal pattern similar to that observed before the COVID-19 pandemic was noted. Furthermore, correlation analysis between the rates of influenza-like illness and COVID-19 incidence showed no significant correlation during the entire period. However, a significant correlation emerged in 2023 (r = 0.393, p <0.05). These results suggest that influenza was suppressed during the COVID-19 pandemic but returned to typical seasonal patterns after the COVID-19 prevention policies were eased.

CONCLUSION

The positive correlation observed between the incidences of COVID-19 and influenza in 2023 indicates that COVID-19, no longer a novel pandemic-causing infectious disease, may have transitioned to an endemic pattern similar to seasonal influenza.

Ten-year analgesic utilization patterns and economic implications in Portugal

AIMS

This study evaluated the 10-year consumption and economic patterns of classical analgesics, adjuvants and opioids in Portugal (2012-2022), and conducted a comparative analysis between Portugal, Spain and Denmark to explore the consumption patterns among these countries for 2022.

METHODS

Data on sales and national health service (NHS) costs were obtained from the Portuguese National Authority of Medicines and Health Products. Sales data were converted to defined daily dose (DDD) per 1000 inhabitants per day according to the Anatomical Therapeutic Chemical (ATC) classification/DDD methodology, while comparisons between Spain and Denmark were evaluated with the chi-square test, when appropriate.

RESULTS

The findings reveal that classical analgesics use in Portugal remained stable during the period 2012-2022, with ibuprofen being the most consumed. Adjuvants, specifically gabapentinoids, experienced an 84% increase in use, primarily attributed to pregabalin. Weak opioids, led by tramadol, witnessed a 117% rise in use, while strong opioid use, led by tapentadol, increased by 618%. Portugal presented the lowest overall opioid consumption when compared to Denmark and Spain in 2022. Economic trends indicated a heightened NHS expenditure on analgesics, primarily driven by increased opioid use. Notwithstanding, there was no significant burden on relative expenditure over the 10-year period.

CONCLUSIONS

Portugal presented a major increase in both weak and strong opioid prescriptions, aligning with the trends for Spain and Denmark. The development and approval of generic medicines and vigilant market monitoring are imperative strategies for managing the escalated costs resulting from heightened consumption, particularly concerning opioids.

Severe Acute Respiratory Infection (SARI) due to Influenza in Post-COVID Resurgence: Disproportionate Impact on Older Māori and Pacific Peoples

OBJECTIVE

Influenza reemerged after a 2020-2021 hiatus in 2022, but understanding the resurgence needs pre-COVID era surveillance. We compared age- and ethnicity-specific incidence of severe acute respiratory infection (SARI) from a hospital network in Auckland, New Zealand, in 2022 against a baseline, 2012-2019.

METHODS

Annual and monthly influenza SARI incidence per 1000 persons by age and ethnic group between 2012 and 2022 was calculated using resident population as the denominator. The hospitals capture most severe illness of the resident population.

RESULTS

Influenza SARI incidence was highest among <1 year olds (2.62; 95% CI: 1.84-3.61) during 2012-2019, lowest at 6-14 years, and did not significantly increase until 50-64 years (0.35; 95% CI: 0.27-0.45), reaching 1.19 (95% CI: 0.57-1.55) in those ≥75 years. In all age groups, incidence was at least threefold higher in Māori and Pacific Peoples. No influenza SARI was identified in 2020-2021. In 2022, despite an early peak, annual incidence (<65 years) was lower than baseline in all ethnic groups, but incidence (≥65 years) in Māori (2.06; 95% CI: 1.22-3.26) and Pacific (3.94; 95% CI: 2.97-5.13) peoples was higher in 2022 than most baseline years, whereas incidence in NMNP (0.22; 95% CI: 0.14-0.32) was lower than any baseline year.

CONCLUSION

After no influenza 2020-2021, Auckland had an early, high, narrow peak in 2022. Stratification by age and ethnicity revealed striking discrepancies in incidence among Māori and Pacific adults over 65 years compared with NMNP adults, with implications for targeted vaccination strategies.

Patients with influenza admitted to a tertiary-care hospital in Riyadh between 2018 and 2022: characteristics, outcomes and factors associated with ICU admission and mortality

BACKGROUND

Influenza is a common cause of hospital admissions globally with regional variations in epidemiology and clinical profile. We evaluated the characteristics and outcomes of patients with influenza admitted to a tertiary-care center in Riyadh, Saudi Arabia.

METHODS

This was a retrospective cohort of adult patients admitted with polymerase chain reaction-confirmed influenza to King Abdulaziz Medical City-Riyadh between January 1, 2018, and May 31, 2022. We compared patients who required intensive care unit (ICU) admission to those who did not and performed multivariable logistic regression to assess the predictors of ICU admission and hospital mortality.

RESULTS

During the study period, 675 adult patients were hospitalized with influenza (median age 68.0 years, females 53.8%, hypertension 59.9%, diabetes 55.1%, and chronic respiratory disease 31.1%). Most admissions (83.0%) were in the colder months (October to March) in Riyadh with inter-seasonal cases even in the summertime (June to August). Influenza A was responsible for 79.0% of cases, with H3N2 and H1N1 subtypes commonly circulating in the study period. Respiratory viral coinfection occurred in 12 patients (1.8%) and bacterial coinfection in 42 patients (17.4%). 151 patients (22.4%) required ICU admission, of which 62.3% received vasopressors and 48.0% mechanical ventilation. Risk factors for ICU admission were younger age, hypertension, bilateral lung infiltrates on chest X-ray, and Pneumonia Severity Index. The overall hospital mortality was 7.4% (22.5% for ICU patients, p < 0.0001). Mortality was 45.0% in patients with bacterial coinfection, 30.9% in those requiring vasopressors, and 29.2% in those who received mechanical ventilation. Female sex (odds ratio [OR], 2.096; 95% confidence interval [CI] 1.070, 4.104), ischemic heart disease (OR, 3.053; 95% CI 1.457, 6.394), immunosuppressed state (OR, 7.102; 95% CI 1.803, 27.975), Pneumonia Severity Index (OR, 1.029; 95% CI, 1.017, 1.041), leukocyte count and serum lactate level (OR, 1.394; 95% CI, 1.163, 1.671) were independently associated with hospital mortality.

CONCLUSIONS

Influenza followed a seasonal pattern in Saudi Arabia, with H3N2 and H1N1 being the predominant circulating strains during the study period. ICU admission was required for > 20%. Female sex, high Pneumonia Severity Index, ischemic heart disease, and immunosuppressed state were associated with increased mortality.

The resurgence of influenza A/H3N2 virus in Australia after the relaxation of COVID-19 restrictions during the 2022 season

This study retrospectively analyzed the genetic characteristics of influenza A H3N2 (A/H3N2) viruses circulating in New South Wales (NSW), the Australian state with the highest number of influenza cases in 2022, and explored the phylodynamics of A/H3N2 transmission within Australia during this period. Sequencing was performed on 217 archived specimens, and A/H3N2 evolution and spread within Australia were analyzed using phylogenetic and phylodynamic methods. Hemagglutinin genes of all analyzed NSW viruses belonged to subclade 3C.2a1b.2a.2 and clustered together with the 2022 vaccine strain. Complete genome analysis of NSW viruses revealed highly frequent interclade reassortments between subclades 3C.2a1b.2a.2 and 3C.2a1b.1a. The estimated earliest introduction time of the dominant subgroup 3C.2a1b.2a.2a.1 in Australia was February 22, 2022 (95% highest posterior density: December 19, 2021-March 13, 2022), following the easing of Australian travel restrictions, suggesting a possible international source. Phylogeographic analysis revealed that Victoria drove the transmission of A/H3N2 viruses across the country during this season, while NSW did not have a dominant role in viral dissemination to other regions. This study highlights the importance of continuous surveillance and genomic characterization of influenza viruses in the postpandemic era, which can inform public health decision-making and enable early detection of novel strains with pandemic potential.

Sequence analysis of respiratory syncytial virus cases reveals a novel subgroup -B strain circulating in north-central Italy after pandemic restrictions

BACKGROUND

Following the pandemic restrictions, the epidemiology of respiratory syncytial virus (RSV) has changed, leading to intense hospitalization peaks.

OBJECTIVES

This study, conducted at multiple sites in Italy, aimed to describe the temporal dynamics of two post-COVID-19 RSV epidemics. Additionally, the circulating RSV-A and -B lineages were characterized and compared to those found in 2018 and 2019.

STUDY DESIGN

Respiratory specimens and data were collected from RSV-positive patients, both inpatients, and outpatients, of all ages at three sites in north-central Italy. To analyze these samples, roughly one-sixth were sequenced in the attachment glycoprotein G gene and subjected to phylogenetic and mutational analyses, including pre-pandemic sequences from north-central Italy.

RESULTS

The first post-pandemic surge of RSV cases was quite intense, occurring from October 2021 to early January 2022. The subsequent RSV epidemic (from November 2022 to early March 2023) also had a high impact, characterized by a rise in elderly patient cases. Post-pandemic cases of RSV-A were caused by various strains present in Italy prior to COVID-19. In contrast, a distinct RSV-B lineage, which was concurrently spreading in other countries, was identified as the main cause of the surge in 2022-2023 but remained undetected in Italy before the pandemic.

CONCLUSIONS

This study describes the temporal dynamics of post-pandemic RSV subgroups and uncovers a lineage of RSV-B with high genetic divergence that may have increased the impact of decreased population immunity.

An end-point multiplex RT-PCR for SARS-CoV-2, Influenza A and B detection, including simultaneous RNAse P amplification: a timely tool for more accessible differential diagnosis

The multiplex molecular diagnostic assays described for severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), influenza A (IAV) and B (IBV) viruses have been mainly based on real-time reaction, which limits their access to many laboratories or diagnostic institutions. To contribute to available strategies and expand access to differential diagnosis, we describe an end-point multiplex RT-PCR targeting SARS-CoV-2, IAV and IBV with simultaneous endogenous control amplification. Initially, we looked for well-established primers sets for SARS-CoV-2, IAV, IBV and RNAse P whose amplicons could be distinguished on agarose gel. The multiplex assay was then standardized by optimizing the reaction mix and cycle conditions. The limit of detection (LoD) was determined using titrated viruses (for SARS-CoV-2 and IAV) and by dilution from a pool of IBV-positive samples. The diagnostic performance of the multiplex was evaluated by testing samples with different RNAse P and viral loads, previously identified as positive or negative for the target viruses. The amplicons of IAV (146 bp), SARS-CoV-2 (113 bp), IBV (103 bp) and RNAse P (65 bp) were adequately distinguished in our multiplex. The LoD for SARS-CoV-2, IAV and IBV was 0.02 TCID50/ml, 0.07 TCID50/ml and 10-3 from a pool of positive samples, respectively. All samples positive for SARS-CoV-2 (n=70, Ct 17.2-36.9), IAV (n=53, Ct 14-34.9) and IBV (n=12, Ct 23.9-31.9) remained positive in our multiplex assay. RNAse P from negative samples (n=40, Ct 25.2-30.2) was also amplified in the multiplex. Overall, our assay is a timely and alternative tool for detecting SARS-CoV-2 and influenza viruses in laboratories with limited access to supplies/equipment.

Attitudes, Beliefs, and Intention to Receive a COVID-19 Vaccine for Pediatric Patients With Sickle Cell Disease

Sickle cell disease (SCD), which occurs primarily in individuals of African descent, has been identified as a preexisting health condition for COVID-19 with higher rates of hospitalization, intensive care unit admissions, and death. National data indicate Black individuals have higher rates of vaccine hesitancy and lower COVID-19 vaccination rates. Understanding the key predictors of intention to receive a COVID-19 vaccine is essential as intention is strongly associated with vaccination behavior. This multisite study examined attitudes, beliefs, intentions to receive COVID-19 vaccines, and educational preferences among adolescents, young adults, and caregivers of children living with SCD. Participants completed an online survey between July 2021 and March 2022. Multivariate logistic regression was used to examine the association between participant age and COVID-19 vaccine attitudes, beliefs, and vaccine intentions. Of the 200 participants, 65.1% of adolescents, 62.5% of young adults, and 48.4% of caregivers intended to receive a COVID-19 vaccine for themselves or their child. Perception that the vaccine was safe was statistically significant and associated with patient and caregiver intention to receive the COVID-19 vaccine for themselves or their child. Participant age was also statistically significant and associated with the intent to get a booster for patients. Study findings highlight key concerns and influencers identified by patients with SCD and their caregivers that are essential for framing COVID-19 vaccine education during clinical encounters. Study results can also inform the design of messaging campaigns for the broader pediatric SCD population and targeted interventions for SCD subpopulations (eg, adolescents, caregivers).

Outbreak of influenza and SARS-CoV-2 at the Armed Forces of the Philippines Health Service Education and Training Center, September 25-October 10, 2023

In the last week of September 2023, a surge of influenza-like illness was observed among students of the Armed Forces of the Philippines (AFP) Health Service Education and Training Center, where 48 (27 males and 21 females; age in years: mean 33, range 27-41) of 247 military students at the Center presented with respiratory symptoms. Between September 25 and October 10, 2023, all 48 symptomatic students were evaluated with real-time reverse transcription polymerase chain reaction and sequencing for both influenza and SARS-CoV-2. Thirteen (27%) students were found positive for influenza A/H3 only, 6 (13%) for SARS-CoV-2 only, and 4 (8%) were co-infected with influenza A/H3 and SARS-CoV-2. Seventeen influenza A/ H3N2 viruses belonged to the same clade, 3C.2a1b.2a.2a.3a, and 4 SARSCoV-2 sequences belonged to the JE1.1 lineage, indicating a common source outbreak for both. The influenza A/H3N2 circulating virus belonged to a different clade than the vaccine strain for 2023 (3C.2a1b.2a.2a). Only 4 students had received the influenza vaccine for 2023. In response, the AFP Surgeon General issued a memorandum to all military health institutions on October 19, 2023 that mandated influenza vaccination as a prerequisite for enrollment of students at all education and training centers, along with implementation of non-pharmaceutical interventions and early notification and testing of students exhibiting influenza-like-illness.

Risk Factors for Severe COVID-19 Among Children and Adolescents Enrolled in Acute Respiratory Infection Sentinel Surveillance in South Africa, 2020-2022

BACKGROUND

Identifying children at risk for severe COVID-19 disease from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may guide future mitigation interventions. Using sentinel surveillance data, we aimed to identify risk factors for SARS-CoV-2-associated hospitalisation among patients aged ≤ 18 years with respiratory illness.

METHODS

From April 2020 to March 2022, patients meeting study case definitions were enrolled at four outpatient influenza-like illness (ILI) and five inpatient severe respiratory infection (SRI) surveillance sites and tested for SARS-CoV-2 infection using polymerase chain reaction (PCR). Each ILI clinic shared a catchment area with its corresponding SRI hospital. Potential risk factors for SARS-CoV-2-associated hospitalisation were analysed using multivariable logistic regression by comparing inpatient versus outpatient SARS-CoV-2 cases.

RESULTS

Of 4688 participants aged ≤ 18 years, 4556 (97%) with complete PCR and HIV data were included in the analysis. Among patients with ILI and SRI, 92/1145 (8%) and 154/3411 (5%) tested SARS-CoV-2 positive, respectively. Compared to outpatients, hospitalised SARS-CoV-2 cases were associated with age < 6 months ([adjusted odds ratio (aOR) 8.0, 95% confidence interval (CI) 2.7-24.0] versus 1-4 years); underlying medical condition other than HIV [aOR 5.8, 95% CI 2.3-14.6]; laboratory-confirmed Omicron BA.1/BA.2 or Delta variant ([aOR 4.9, 95% CI 1.7-14.2] or [aOR 2.8, 95% CI 1.1-7.3] compared to ancestral SARS-CoV-2); and respiratory syncytial virus coinfection [aOR 6.2, 95% CI 1.0-38.5].

CONCLUSION

Aligning with previous research, we identified age < 6 months or having an underlying condition as risk factors for SARS-CoV-2-associated SRI hospitalisation and demonstrated the potential of sentinel surveillance to monitor COVID-19 in children.

The Role and Value of Professional Rapid Testing of Acute Respiratory Infections (ARIs) in Europe: A Special Focus on the Czech Republic, Poland, and Romania

This review aims to explore the role of professional diagnostic rapid testing of acute respiratory infections (ARIs), especially COVID-19 and influenza, ensuring proper disease management and treatment in Europe, and particularly in Czech Republic, Poland, and Romania. The paper was constructed based on a review of scientific evidence and national and international policies and recommendations, as well as a process of validation by four experts. The development of new testing technologies, treatment options, and increased awareness of the negative multidimensional impact of ARI profiles transformed differential diagnosis into a tangible and desirable reality. This review covers the following topics: (1) the multidimensional impact of ARIs, (2) ARI rapid diagnostic testing platforms and their value, (3) the policy landscape, (4) challenges and barriers to implementation, and (5) a set of recommendations illustrating a path forward. The findings indicate that rapid diagnostic testing, including at the point of care (POC), can have a positive impact on case management, antimicrobial and antibiotic stewardship, epidemiological surveillance, and decision making. Integrating this strategy will require the commitment of governments and the international and academic communities, especially as we identified room for improvement in the access and expansion of POC rapid testing in the focus countries and the inclusion of rapid testing in relevant policies.

Integrating dynamical modeling and phylogeographic inference to characterize global influenza circulation

Global seasonal influenza circulation involves a complex interplay between local (seasonality, demography, host immunity) and global factors (international mobility) shaping recurrent epidemic patterns. No studies so far have reconciled the two spatial levels, evaluating the coupling between national epidemics, considering heterogeneous coverage of epidemiological and virological data, integrating different data sources. We propose a novel combined approach based on a dynamical model of global influenza spread (GLEAM), integrating high-resolution demographic and mobility data, and a generalized linear model of phylogeographic diffusion that accounts for time-varying migration rates. Seasonal migration fluxes across global macro-regions simulated with GLEAM are tested as phylogeographic predictors to provide model validation and calibration based on genetic data. Seasonal fluxes obtained with a specific transmissibility peak time and recurrent travel outperformed the raw air-transportation predictor, previously considered as optimal indicator of global influenza migration. Influenza A subtypes supported autumn-winter reproductive number as high as 2.25 and an average immunity duration of 2 years. Similar dynamics were preferred by influenza B lineages, with a lower autumn-winter reproductive number. Comparing simulated epidemic profiles against FluNet data offered comparatively limited resolution power. The multiscale approach enables model selection yielding a novel computational framework for describing global influenza dynamics at different scales - local transmission and national epidemics vs. international coupling through mobility and imported cases. Our findings have important implications to improve preparedness against seasonal influenza epidemics. The approach can be generalized to other epidemic contexts, such as emerging disease outbreaks to improve the flexibility and predictive power of modeling.

Influenza vaccination before and during the COVID-19 pandemic in the elderly in South Korea

BACKGROUND

Influenza epidemics are a significant cause of mortality and morbidity in older adults; thus, vaccination is recommended. However, the coronavirus disease 2019 (COVID-19) pandemic could affect influenza vaccination.

METHODS

The influenza vaccination rate was estimated from the Korea Community Health Survey data from 2011 to 2021 using Joinpoint regression. We used multiple logistic regression analysis from each two flu seasons data before (2017-18 and 2018-19 seasons) and during (2019-20 and 2020-21 seasons) the COVID-19 pandemic to identify older adults who were not been vaccinated during the COVID-19 pandemic. Additionally, we stratified changes in influenza vaccination according to the flu season, demographic and socioeconomic characteristics, and health status.

RESULTS

The annual percentage change in influenza non-vaccination rate from 2010-11 to 2018-19 seasons and from 2019-20 to 2020-21 seasons was -8.31% (confidence interval (CI), -9.60 to -7.00) and 11.41% (CI, -3.22 to 28.25), respectively. Compared to before COVID-19, in the 2019-20 and 2020-21 seasons, the odds ratio (OR) of non-vaccination was 0.87 (CI, 0.83-0.91) and 1.18 (95% CI, 1.13-1.24), respectively. The decrease in influenza vaccination among older individuals with higher education (OR, 1.24; CI, 1.11-1.39) was greater than that among those with lower education (OR, 1.09; CI, 0.98-1.22). Older individuals with the lowest income level or poor self-rated health showed reduced influenza vaccination.

CONCLUSIONS

We estimated the trends of influenza vaccination and identified subgroups with decreased vaccination rates during the COVID-19 pandemic among older adults in South Korea. Health policy decision-makers, practitioners, and researchers should consider the implications of COVID-19 on changes in influenza vaccination, particularly for older individuals at risk of influenza.

Changes in clinical, demographic, and outcome patterns of children hospitalized with non-SARS-CoV-2 viral low respiratory tract infections before and during the COVID pandemic in Rome, Italy

INTRODUCTION

We performed this study aiming to evaluate changes in epidemiology, clinical presentation and outcomes of children hospitalized for viral lower respiratory tract infections (LRTI).

METHODS

We performed a retrospective study of children younger than 18 years of age hospitalized for LRTIs with a positive respiratory viral testing from 2018 to 2022. We compared need of pediatric intensive care unit (PICU), invasive ventilation, and other respiratory support, viral etiologies, clinical presentations, imaging, and laboratory results in the precovid (2018-2019) and covid (2020-2022) period.

RESULTS

A total of 523 were included in the analysis. In the pandemic period, the detection of influenza was 95% less likely to occur (odds ratio [OR]: 0.05; 95% confidence interval [95% CI]: 0.02-0.12; p < .001), likewise the detection of adenovirus was 77% less likely to occur (OR: 0.23; 95% CI: 0.10-0.51; p < .001). In the pandemic period, the number of codetections increased from 15.52% in 2018 to 57.25% in 2022, resulting in a significantly increasing trend (p < .001). The odds of transfer to PICU was more than five times greater during the pandemic period (OR: 5.31; 95% CI: 1.78-15.86; p = .003).

CONCLUSIONS

We found that the pattern of LRTI in children during COVID-19 pandemic significantly changed in terms of etiologies and increased severity.

Quantified impacts of non-pharmaceutical interventions on influenza circulation during the COVID-19 pandemic in 13 African countries, 2020-2022

Nonpharmaceutical interventions (NPIs) for SARS-CoV-2 disrupted circulation of influenza. We used data from 13 African countries and generalized linear models to identify associations between levels of NPIs, using the Oxford Stringency Index, and seasonal influenza activity, using parameters derived from 2020-2022 seasonal influenza surveillance. We found that for each step increase in school closings, the average percentage of respiratory specimens testing positive for influenza across the influenza season dropped by 20% (95% CI: 1-38%); no other NPI was significant. These findings may inform interventions to slow influenza circulation in pandemics and possibly during seasonal epidemics.

Frequency of respiratory virus-associated infection among children and adolescents from a tertiary-care hospital in Mexico City

Acute respiratory infections (ARIs) are a major cause of morbidity and mortality among children. The causative pathogens show geographic and seasonal variations. We retrospectively evaluated the frequency and seasonality of respiratory pathogens in children and adolescents (age: 0-19 years) with ARIs treated between January 1, 2021, and March 31, 2022, at a single center in Mexico. Out of 2400 patients, 1,603 were diagnosed with SARS-CoV-2 infection and 797 were diagnosed with other common respiratory pathogens (CRPs). Of the 797 patients, 632 were infected with one CRP and 165 with > 2 CRPs. Deaths occurred only in SARS-CoV-2-infected patients. Rhinovirus/Enterovirus, respiratory syncytial virus B, and parainfluenza virus 3 were the most prevalent in cases with single and multiple infections. CRP showed a high frequency between autumn and winter of 2021, with higher incidence of hospitalization compared to COVID-19. The main comorbidities were immunosuppression, cardiovascular disease (CD), and asthma. The frequency of CRPs showed a downward trend throughout the first half of 2021. CRPs increased in single- and co-infection cases between the fourth and fifth waves of COVID-19, probably due to decreased nonpharmaceutical interventions and changes in diagnostic tests. Age, cyanosis (symptom), and immunosuppression (comorbidity) were found to differentiate between SARS-CoV-2 infection and CRP infection.