Comparison of two new generation influenza rapid diagnostic tests with instrument-based digital readout systems for influenza virus detection

Risk of cardiovascular events after influenza infection-related hospitalizations in adults with congenital heart disease: A nationwide population based study

BACKGROUND

Cardiovascular complications due to viral infection pose a significant risk in vulnerable patients such as those with congenital heart disease (CHD). Limited data exists regarding the incidence of influenza and its impact on cardiovascular outcomes among this specific patient population.

METHODS

A retrospective cohort study was designed using the Canadian Congenital Heart Disease (CanCHD) database-a pan-Canadian database of CHD patients with up to 35 years of follow-up. CHD patients aged 40 to 65 years with influenza virus-associated hospitalizations between 2010 and 2017 were identified and 1:1 matched with CHD patients with limb fracture hospitalizations on age and calendar time. Our primary endpoint was cardiovascular complications: heart failure, acute myocardial infarction, atrial arrhythmia, ventricular arrhythmia, heart block, myocarditis, and pericarditis.

RESULTS

Of the 303 patients identified with incident influenza virus-associated hospitalizations, 255 were matched to 255 patients with limb fracture hospitalizations. Patients with influenza virus-related hospitalizations showed significantly higher cumulative probability of cardiovascular complications at 1 year (0.16 vs. 0.03) and 5 years (0.33 vs. 0.15) compared to patients hospitalized with bone fracture. Time-dependent hazard function modeling demonstrated a significantly higher risk of cardiovascular complications within 9 months postdischarge for influenza-related hospitalizations. This association was confirmed by Cox regression model (average hazard ratio throughout follow-up: 2.48; 95% CI: 1.59-3.84).

CONCLUSIONS

This pan-Canadian cohort study of adults with CHD demonstrated an association between influenza virus-related hospitalization and risk of cardiovascular complications during the 9 months post discharge. This data is essential in planning surveillance strategies to mitigate adverse outcomes and provides insights into interpreting complication rates of other emerging pathogens, such as COVID-19.

A narrative review of nine commercial point of care influenza tests: an overview of methods, benefits, and drawbacks to rapid influenza diagnostic testing

CONTEXT

Rapid influenza diagnostic tests (RIDTs) are becoming increasingly accurate, available, and reliable as the first line of testing when suspecting influenza infections, although the global burden of influenza infections remains high. Rapid diagnosis of influenza infections has been shown to reduce improper or delayed treatment and to increase access to diagnostic measures in public health, primary care, and hospital-based settings.

OBJECTIVES

As the use of RIDTs continues to expand in all healthcare settings, there is a multitude of molecular techniques being employed by these various testing platforms. With this in mind, we compare the sensitivity, specificity, and time to diagnosis for nine highly utilized commercial RIDTs.

METHODS

Nine commercially available RIDTs were identified from the US Centers for Disease Control and Prevention (CDC) website, which were also referenced on PubMed by name within the title or abstract of peer-reviewed publications examining the sensitivity and specificity of each test against a minimum of three influenza A virus (IAV) strains as well as seasonal influenza B virus (IBV). Data from the peer-reviewed publications and manufacturers' websites were combined to discuss the sensitivity, specify, and time to diagnosis associated with each RIDT.

RESULTS

The sensitivity and specificity across the examined RIDTs were greater than 85.0% for both IAV and IBV across all platforms, with the reverse transcriptase-polymerase chain reaction (RT-PCR) assays maintaining sensitivity and specificity greater than 95.0% for all viruses tested. However, the RT-PCR platforms were the longest in time to diagnosis when compared to the other molecular methods utilized in the examined RIDTs.

CONCLUSIONS

Herein, we discussed the benefits and limitations of nine commercially available RIDTs and the molecular techniques upon which they are based, showing the relative accuracy and speed of each test for IAV and IBV detection as reported by the peer-reviewed literature and commercial manufacturers.

Unintended beneficial effects of COVID-19 on influenza-associated emergency department use in Korea

BACKGROUND

Non-pharmaceutical interventions, including hand hygiene, wearing masks, and cough etiquette, and public health measures such as social distancing, used to prevent the spread of coronavirus disease 2019 (COVID-19), could reduce the incidence rate of respiratory viral infections such as influenza. We evaluated the effect of COVID-19 on the incidence of influenza in Korea.

METHODS

This retrospective study included all patients who visited five urban emergency departments (EDs) during the influenza epidemic seasons of 2017-18, 2018-19, and 2019-20. Influenza was defined as ICD-10 codes J09, J10, and J11, determined from ED discharge records. The weekly incidence rates of influenza per 1000 ED visits during the 2019-20 season, when COVID-19 became a pandemic, were compared with those of 2017-18 and 2018-19. The actual incidence rate of the 2019-20 season was compared with the predicted value using a generalized estimation equation model based on 2017-18 and 2018-19 data.

RESULTS

The weekly influenza incidence rate decreased from 101.6 to 56.6 between week 4 and week 5 in 2020 when the first COVID-19 patient was diagnosed and public health measures were implemented. The weekly incidence rate during week 10 and week 22 of the 2019-20 season decreased most steeply compared to 2017-18 and 2018-19. The actual influenza incidence rate observed in the 2019-20 season was lower than the rate predicted in the 2017-18 and 2018-19 seasons starting from week 7 when a COVID-19 outbreak occurred in Korea.

CONCLUSIONS

The implementation of non-pharmaceutical interventions and public health measures for the COVID-19 epidemic effectively reduced the transmission of influenza and associated ED use in Korea. Implementing appropriate public health measures could reduce outbreaks and lessen the burden of influenza during future influenza epidemics.

Nanopore sensors for viral particle quantification: current progress and future prospects

Rapid, inexpensive, and laboratory-free diagnostic of viral pathogens is highly critical in controlling viral pandemics. In recent years, nanopore-based sensors have been employed to detect, identify, and classify virus particles. By tracing ionic current containing target molecules across nano-scale pores, nanopore sensors can recognize the target molecules at the single-molecule level. In the case of viruses, they enable discrimination of individual viruses and obtaining important information on the physical and chemical properties of viral particles. Despite classical benchtop virus detection methods, such as amplification techniques (e.g., PCR) or immunological assays (e.g., ELISA), that are mainly laboratory-based, expensive and time-consuming, nanopore-based sensing methods can enable low-cost and real-time point-of-care (PoC) and point-of-need (PoN) monitoring of target viruses. This review discusses the limitations of classical virus detection methods in PoN virus monitoring and then provides a comprehensive overview of nanopore sensing technology and its emerging applications in quantifying virus particles and classifying virus sub-types. Afterward, it discusses the recent progress in the field of nanopore sensing, including integrating nanopore sensors with microfabrication technology, microfluidics and artificial intelligence, which have been demonstrated to be promising in developing the next generation of low-cost and portable biosensors for the sensitive recognition of viruses and emerging pathogens.

Diagnostic Accuracy of the Quidel Sofia Rapid Influenza Fluorescent Immunoassay in Patients with Influenza-like Illness: A Systematic Review and Meta-analysis

Background

Although the Quidel Sofia rapid influenza fluorescent immunoassay (FIA) is widely used to identify influenza A and B, the diagnostic accuracy of this test remains unclear. Thus, the objective of this study was to determine the diagnostic performance of this test compared to reverse transcriptase-polymerase chain reaction.

Methods

A systematic literature search was performed using MEDLINE, EMBASE, and the Cochrane Central Register. Pooled sensitivity, specificity, diagnostic odds ratio (DOR), and a hierarchical summary receiver-operating characteristic curve (HSROC) of this test for identifying influenza A and B were determined using meta-analysis. A sensitivity subgroup analysis was performed to identify potential sources of heterogeneity within selected studies.

Results

We identified 17 studies involving 8,334 patients. Pooled sensitivity, specificity, and DOR of the Quidel Sofia rapid influenza FIA for identifying influenza A were 0.78 (95% confidence interval [CI], 0.71–0.83), 0.99 (95% CI, 0.98–0.99), and 251.26 (95% CI, 139.39–452.89), respectively. Pooled sensitivity, specificity, and DOR of this test for identifying influenza B were 0.72 (95% CI, 0.60–0.82), 0.98 (95% CI, 0.96–0.99), and 140.20 (95% CI, 55.92–351.54), respectively. The area under the HSROC for this test for identifying influenza A was similar to that for identifying influenza B. Age was considered a probable source of heterogeneity.

Conclusion

Pooled sensitivities of the Quidel Sofia rapid influenza FIA for identifying influenza A and B did not quite meet the target level (≥80%). Thus, caution is needed when interpreting data of this study due to substantial between-study heterogeneity.

Virus Detection: A Review of the Current and Emerging Molecular and Immunological Methods

Viruses are ubiquitous in the environment. While many impart no deleterious effects on their hosts, several are major pathogens. This risk of pathogenicity, alongside the fact that many viruses can rapidly mutate highlights the need for suitable, rapid diagnostic measures. This review provides a critical analysis of widely used methods and examines their advantages and limitations. Currently, nucleic-acid detection and immunoassay methods are among the most popular means for quickly identifying viral infection directly from source. Nucleic acid-based detection generally offers high sensitivity, but can be time-consuming, costly, and require trained staff. The use of isothermal-based amplification systems for detection could aid in the reduction of results turnaround and equipment-associated costs, making them appealing for point-of-use applications, or when high volume/fast turnaround testing is required. Alternatively, immunoassays offer robustness and reduced costs. Furthermore, some immunoassay formats, such as those using lateral-flow technology, can generate results very rapidly. However, immunoassays typically cannot achieve comparable sensitivity to nucleic acid-based detection methods. Alongside these methods, the application of next-generation sequencing can provide highly specific results. In addition, the ability to sequence large numbers of viral genomes would provide researchers with enhanced information and assist in tracing infections.

Evaluation of high-throughput digital lateral flow immunoassays for the detection of influenza A/B viruses from clinical swab samples

We evaluated the performance of new high-throughput digital lateral flow immunoassays (LFIAs) detecting influenza antigens and compared them with those of the widely used digital LFIA and the rapid nucleic acid amplification test (NAAT). We tested 199 clinical nasopharyngeal (nasal) swab samples using three LFIA tests (BD Veritor Plus, STANDARD F Influenza A/B FIA, and ichroma TRIAS) and the rapid NAAT (ID NOW Influenza A & B2). Agreements and clinical performances (sensitivity and specificity) were evaluated based on the results of reverse transcriptase-polymerase chain reaction (RT-PCR) and verification panel. The agreement of each test with RT-PCR was moderate to almost perfect. The sensitivity of ID NOW was significantly higher than that of LFIAs (P = .0005, .0044, and .0026 for influenza A and P = .0044, .0026, and .0044 for influenza B, respectively). The specificities were not significantly different between the four tests (P > .05). However, the reference panel suggests that ichroma TRIAS test is more sensitive than the other two LFIA tests. All three LFIA assays performed similarly with no false positives against influenza A. For influenza B, ichroma TRIAS had 2 of 166 false positives whereas there were no false positives for the other two LFIA tests. Influenza antigen digital LFIAs have advantages in terms of the workflow when simultaneous tests are required. Rapid NAAT has higher sensitivity, while new antigen LFIAs are efficient and high-throughput. It is recommended that users select appropriate methods and algorithms according to the number of specimens and laboratory conditions in each clinical laboratory.

Influenza vaccine and cardiac protection: a study from a tertiary care center

Patients with heart disease (HD) are at increased risk of developing cardiac complications if they acquire the influenza virus. The objective of this study was to determine whether the influenza vaccine has a primary role in preventing newly diagnosed HD in patients who have no history of HD and who were being followed up at the American University of Beirut Medical Center (AUBMC). The study is a retrospective cohort, with 2-years follow up, which was conducted using electronic medical records between the years of 2011-2013 in a tertiary care center. All patients 60 years and older (n = 698) who have taken the flu vaccine were randomly selected from the University Health Service records (UHS) and compared to a group who has not taken the flu vaccine during the same period. The odds of developing HD among vaccinated people with cofactors are 0.97 times the odds of that among non-vaccinated. This odds ratio is not significantly different than that of people vaccinated without cofactors (OR = 1.74). The occurrence of HD in the presence of vaccination revealed a non-significant decrease trend with the increase in a number of risk factors (OR = 1.61 vs 0.97). Our results suggest that there was a non-significant difference between the effect of the vaccine for influenza on patients who had cofactors for HD and those who had not. Similarly, the effect of vaccine showed a non-significant increase in protective effect as the number of comorbidities increase. The potential effects of the vaccine may be related to the protection against flu.

High performance of rapid influenza diagnostic test and variable effectiveness of influenza vaccines in Mexico

OBJECTIVES

To evaluate the performance of rapid influenza diagnostic tests (RIDT) and influenza vaccines' effectiveness (VE) during an outbreak setting.

METHODS

We compared the performance of a RIDT with RT-PCR for influenza virus detection in influenza-like illness (ILI) patients enrolled during the 2016/17 season in Mexico City. Using the test-negative design, we estimated influenza VE in all participants and stratified by age, virus subtype, and vaccine type (trivalent vs quadrivalent inactivated vaccines). The protective value of some clinical variables was evaluated by regression analyses.

RESULTS

We enrolled 592 patients. RT-PCR detected 93 cases of influenza A(H1N1)pdm09, 55 of AH3N2, 141 of B, and 13 A/B virus infections. RIDT showed 90.7% sensitivity and 95.7% specificity for influenza A virus detection, and 91.5% sensitivity and 95.3% specificity for influenza B virus detection. Overall VE was 33.2% (95% CI: 3.0-54.0; p = 0.02) against any laboratory-confirmed influenza infection. VE estimates against influenza B were higher for the quadrivalent vaccine. Immunization and occupational exposure were protective factors against influenza.

CONCLUSIONS

The RIDT was useful to detect influenza cases during an outbreak setting. Effectiveness of 2016/17 influenza vaccines administered in Mexico was low but significant. Our data should be considered for future local epidemiological policies.

Sensitivity enhancement in lateral flow assays: a systems perspective

Lateral flow assays (LFAs) are rapid, inexpensive, easy-to-manufacture and -use tests widely employed in medical and environmental applications, particularly in low resource settings. Historically, LFAs have been stigmatized as having limited sensitivity. However, as their global usage expands, extensive research has demonstrated that it is possible to substantially improve LFA sensitivity without sacrificing their advantages. In this critical review, we have compiled state-of-the-art approaches to LFA sensitivity enhancement. Moreover, we have organized and evaluated these approaches from a system-level perspective, as we have observed that the advantages and disadvantages of each approach have arisen from the integrated and tightly interconnected chemical, physical, and optical properties of LFAs.

Evaluation of rapid influenza diagnostic tests for influenza A and B in the tropics

Rapid diagnosis of influenza is important for early treatment and institution of control measures. In developing tropical countries such as Malaysia, influenza occurs all year round, but molecular assays and conventional techniques (such as immunofluorescence and culture) for diagnosis are not widely available. Rapid influenza diagnostic tests (RIDTs) may be useful in this setting. A total of 552 fresh respiratory specimens were assessed from patients with respiratory symptoms at a teaching hospital in Kuala Lumpur, Malaysia from November 2017 to March 2018. Two digital immunoassays (DIAs), STANDARD F Influenza A/B Fluorescence Immunoassay (STANDARD F) and Sofia Influenza A + B Fluorescence Immunoassay (Sofia) and one conventional RIDT (immunochromatographic assay), SD Bioline Influenza Ag A/B/A(H1N1) Pandemic rapid test kit (SD Bioline) were evaluated in comparison with a WHO-recommended reverse transcription quantitative PCR (RT-qPCR). Of the 552 samples, influenza A virus was detected in 47 (8.5%) and influenza B virus in 7 (1.3%). The digital immunoassays STANDARD F and Sofia had significantly higher overall sensitivity rates (71.7% and 70.6%, respectively) than the conventional RIDT SD Bioline and immunofluorescence/viral culture (55.8% and 52.8%, respectively). Sensitivity rates were higher for influenza A than influenza B, and specificity rates were uniformly high, ranging from 98% to 100%. Digital readout RIDTs can be used in tropical settings with year-round influenza if PCR is unavailable.

Clinical evaluation of rapid fluorescent diagnostic immunochromatographic test for influenza A virus (H1N1)

Rapid diagnostic tests (RDTs) have been developed to detect influenza A virus for the swift diagnosis and management of patients. However, despite the simplicity and convenience, the low sensitivity of RDTs remains a limitation for their use in point of care testing (POCT). In this study, we developed a rapid fluorescent immunochromatographic strip test (FICT) and the performance of FICT was confirmed by the real-time reverse transcription-polymerase chain reaction (rRT-PCR) of H1N1, compared with that of RDT. The limit of detection (LOD) of FICT was improved by 16-fold compared to RDT. FICT showed 85.29% sensitivity (29/34) (95% Confidence Interval [95% CI]: 68.94 to 95.05), 100% specificity (26/26) (95% CI: 86.78 to 100.00), and a strong correlation (kappa; 0. 92) compared with rRT-PCR (20 ≤ Ct ≤ 36). In contrast, RDT (Standard Diagnostics [SD] BIOLINE Influenza Ag A/ B/ A(H1N1) Pandemic) showed 55.88% sensitivity (19/34) (95% CI: 37.87 to 72.82), 100% specificity (26/26) (95% CI: 77.07 to 100), and had a fair correlation with rRT-PCR (kappa; 0. 75). FICT had better sensitivity than RDT (P < 0.01; McNemar’s test). Therefore, FICT has the potential to improve the quality of current rapid POCT for the diagnosis of influenza A/H1N1 infection.

Influenza infection and heart failure-vaccination may change heart failure prognosis?

The interaction of influenza infection with the pathogenesis of acute heart failure (AHF) and the worsening of chronic heart failure (CHF) is rather complex. The deleterious effects of influenza infection on AHF/CHF can be attenuated by specific immunization. Our review aimed to summarize the efficacy, effectiveness, safety, and dosage of anti-influenza vaccination in HF. In this literature review, we searched MEDLINE and EMBASE from January 1st 1966 to December 31st, 2016, for studies examining the association between AHF/CHF, influenza infections, and anti-influenza immunizations. We used broad criteria to increase the sensitivity of the search. HF was a prerequisite for our search. The search fields used included “heart failure,” “vaccination,” “influenza,” “immunization” along with variants of these terms. No restrictions on the type of study design were applied. The most common clinical scenario is exacerbation of pre-existing CHF by influenza infection. Scarce evidence supports a potential positive association of influenza infection with AHF. Vaccinated patients with pre-existing CHF have reduced all-cause morbidity and mortality, but effects are not consistently documented. Immunization with higher antigen quantity may confer additional protection, but such aggressive approach has not been generally advocated. Further studies are needed to delineate the role of influenza infection on AHF/CHF pathogenesis and maintenance. Annual anti-influenza vaccination appears to be an effective measure for secondary prevention in HF. Better immunization strategies and more efficacious vaccines are urgently necessary.

Diagnostic performances of the Xpert® Flu PCR test and the OSOM® immunochromatographic rapid test for influenza A and B virus among adult patients in the Emergency Department

BACKGROUND

New rapid influenza diagnostic tests (RIDT) are available but their clinical utility in adults has not been validated.

OBJECTIVES

To evaluate the diagnostic performances of OSOM^® Ultra Flu A&B a RIDT on viral strains of influenza A/B from the last epidemic season, and its feasibility by Emergency Department (ED) physicians and nurses.

STUDY DESIGN

Of the 1099 patients admitted to the ED with suspected influenza, all having a nasopharyngeal swab tested by the Xpert^® Flu PCR and then stored at -20 °C; 500 were selected at random and their samples were tested using the RIDT. Two experts reviewed ED and hospital medical records and all virological data to define influenza cases. Intra- and inter-observer variability were calculated.

RESULTS

Of the 500 patients included 45% were ≥75 years, 122 (24.4%) presented with influenza based on clinical and virological criteria. PCR test performances (%) were Se 98.4 (95% CI 93.6-99.7), Spe 99.7 (98.3-100), PPV 99.2 (94.8-100) and NPV 99.5 (97.9-100); and RIDT performances were Se 95.1 (89.2-97.9), Spe 98.4 (96.4-99.4), PPV 95.1 (87.2-99.9) and NPV 98.4 (96.4-98). There was no difference in test performance between influenza A and B virus nor between the influenza A subtypes. Intra- and inter-observer variability of RIDT were 0.94 (0.89-0.99) and 0.96 (0.92-1).

CONCLUSION

Our results show that the Xpert^® Flu PCR and the OSOM^® Ultra Flu A&B Test perform very well in diagnosing strains of circulating virus in adults and elderly. Our results also confirm the feasibility of this RIDT at point-of-care by ED staff.

Comparison of three rapid influenza diagnostic tests with digital readout systems and one conventional rapid influenza diagnostic test

Background

Rapid influenza diagnostic tests (RIDTs) show variable sensitivities in clinical settings. We aimed to compare three digital RIDTs and one conventional RIDT.

Methods

We assessed 218 nasopharyngeal swabs from patients between neonates and 90 years old in 2016. Three digital RIDTs were BUDDI, Sofia Influenza A+B Fluorescence Immunoassay, Veritor System Flu A+B assay. One conventional test was the SD Bioline Influenza Ag A/B/A(H1N1/2009). All test results were compared with those from the Anyplex Flu A/B Typing Real‐time Detection real‐time PCR. The four RIDTs were tested with diluted solutions from the National Institute for Biological Standards and Control (NIBSC) to compare lower detection limit. Cross‐reactivity of four RIDTs within other respiratory viruses was identified.

Results

For influenza A, BUDDI, Sofia, Veritor, and Bioline showed 87.7%, 94.5%, 87.7%, and 72.6% sensitivity, and 100%, 97.7%, 96.5%, and 100% specificity. For influenza B, BUDDI, Sofia, Veritor, and Bioline showed 81.7%, 91.7%, 81.7%, and 78.3% sensitivity, and 100%, 95.3%, 100%, and 100% specificity, respectively. Each RIDT could detect diluted NIBSC solution, according to the level of dilution and specific influenza subtypes. Cross‐reactivity of four RIDTs with other respiratory viruses was not noted.

Conclusions

Sofia showed the highest sensitivity for influenza A and B detection. BUDDI and Veritor showed higher detection sensitivity than a conventional RIDT for influenza A detection, but similar results for influenza B detection. Further study is needed to compare the test performance of RIDTs according to specific, prevalent influenza subtypes.