Seasonal influenza activity based on laboratory surveillance in Malaysia, 2011-2016

Cross-sectional study of influenza trends and costs in Malaysia between 2016 and 2018

BACKGROUND AND OBJECTIVES

While influenza circulates year-round in Malaysia, research data on its incidence is scarce. Yet, this information is vital to the improvement of public health through evidence-based policies. In this cross-sectional study, we aimed to determine the trends and financial costs of influenza.

METHODS

Data for the years 2016 through 2018 were gathered retrospectively from several sources. These were existing Ministry of Health (MOH) influenza sentinel sites data, two teaching hospitals, and two private medical institutions in the Klang Valley, Malaysia. Expert consensus determined the final estimates of burden for laboratory-confirmed influenza-like illness (ILI) and severe acute respiratory infection (SARI). Economic burden was estimated separately using secondary data supplemented by MOH casemix costing.

RESULTS

Altogether, data for 11,652 cases of ILI and 5,764 cases of SARI were extracted. The influenza B subtype was found to be predominant in 2016, while influenza A was more prevalent in 2017 and 2018. The distribution timeline revealed that the highest frequency of cases occurred in March and April of all three years. The costs of influenza amounted to MYR 310.9 million over the full three-year period.

CONCLUSIONS

The study provides valuable insights into the dynamic landscape of influenza in Malaysia. The findings reveal a consistent year-round presence of influenza with irregular seasonal peaks, including a notable influenza A epidemic in 2017 and consistent surges in influenza B incidence during March across three years. These findings underscore the significance of continuous monitoring influenza subtypes for informed healthcare strategies as well as advocate for the integration of influenza vaccination into Malaysia's national immunization program, enhancing overall pandemic preparedness.

Cost effectiveness of quadrivalent influenza vaccines in the elderly population of Malaysia

The economic burden of influenza is a significant issue within healthcare system, related to higher medical costs particularly among the elderly. Yet, influenza vaccination rates in the elderly in Malaysia were considerably low as it is not part of Malaysia's national immunization program, with substantial mortality and morbidity consequences. Therefore, we conducted a cost-effectiveness analysis of quadrivalent influenza vaccine (QIV) for the elderly in Malaysia compared with the current no-vaccination policy. A static cost-utility model, with a lifetime horizon based on age, was used for the analysis to assess the cost-effectiveness and health outcomes associated with QIV. Univariate and probabilistic sensitivity analyses were performed to test the effects of variations in the parameters. The use of QIV in Malaysia's elderly population would prevent 66,326 potential influenza cases and 888 potential deaths among the elderly, leading to 10,048 potential quality-adjusted life years (QALYs) gained. The QIV would also save over USD 4.4 million currently spent on influenza-related hospitalizations and reduce productivity losses by approximately USD 21.6 million. The ICER per QALY gained from a third-party payer's perspective would be USD 2216, which is lower than the country's gross domestic product per capita. A QIV-based vaccination program in the elderly was found to be highly cost-effective, therefore would reduce the financial burden of managing influenza and reduce pre-mature death related to this disease.

Exploration of influenza incidence prediction model based on meteorological factors in Lanzhou, China, 2014-2017

Humans are susceptible to influenza. The influenza virus spreads quickly and behave seasonally. The seasonality and spread of influenza are often associated with meteorological factors and have spatio-temporal differences. Based on the influenza cases and daily average meteorological factors in Lanzhou from 2014 to 2017, this study firstly aimed to analyze the characteristics of influenza incidence in Lanzhou and the impact of meteorological factors on influenza activities. Then, SARIMA(X) models for the prediction were established. The influenza cases in Lanzhou from 2014 to 2017 was more male than female, and the younger the age, the higher the susceptibility; the epidemic characteristics showed that there is a peak in winter, a secondary peak in spring, and a trough in summer and autumn. The influenza cases in Lanzhou increased with increasing daily pressure, decreasing precipitation, average relative humidity, hours of sunshine, average daily temperature and average daily wind speed. Low temperature was a significant driving factor for the increase of transmission intensity of seasonal influenza. The SARIMAX (1,0,0)(1,0,1)[12] multivariable model with average temperature has better prediction performance than the university model. This model is helpful to establish an early warning system, and provide important evidence for the development of influenza control policies and public health interventions.

Rhinovirus/enterovirus was the most common respiratory virus detected in adults with severe acute respiratory infections pre-COVID-19 in Kuala Lumpur, Malaysia

Background

Severe acute respiratory infections (SARI) pose a great global burden. The contribution of respiratory viruses to adult SARI is relatively understudied in Asia. We aimed to determine viral aetiology of adult SARI patients in Kuala Lumpur, Malaysia.

Methods

The prevalence of 20 common (mainly viral) respiratory pathogens, and MERS-CoV, SARS-CoV and 5 bacterial select agents was investigated from May 2017 to October 2019 in 489 SARI adult patients in Kuala Lumpur, Malaysia, using molecular assays (Luminex NxTAG-RPP kit and qPCR assays). Viral metagenomics analysis was performed on 105 negative samples.

Results

Viral respiratory pathogens were detected by PCR in 279 cases (57.1%), including 10 (2.0%) additional detections by metagenomics analysis. The most detected viruses were rhinovirus/enterovirus (RV/EV) (49.1%) and influenza virus (7.4%). Three melioidosis cases were detected but no SARS-CoV, MERS-CoV or other bacterial select agents. Bacterial/viral co-detections and viral co-detections were found in 44 (9.0%) and 27 (5.5%) cases respectively, mostly involving RV/EV. Independent predictors of critical disease were male gender, chronic lung disease, lack of runny nose and positive blood culture with a significant bacterial pathogen. Asthma and sore throat were associated with increased risk of RV/EV detection, while among RV/EV cases, males and those with neurological disease were at increased risk of critical disease.

Conclusions

Prior to the COVID-19 pandemic, the high prevalence of respiratory viruses in adults with SARI was mainly attributed to RV/EV. Continued surveillance of respiratory virus trends contributes to effective diagnostic, prevention, and treatment strategies.

Detection of respiratory viruses in adults with suspected COVID-19 in Kuala Lumpur, Malaysia

Background

Reports of co-circulation of respiratory viruses during the COVID-19 pandemic and co-infections with SARS-CoV-2 vary. However, limited information is available from developing countries.

Objectives

We aimed to investigate the incidence of respiratory viruses in adult patients with suspected COVID-19 in Kuala Lumpur, Malaysia.

Study Design

We collected 198 respiratory samples from adult patients hospitalized with suspected COVID-19 in a single teaching hospital in Kuala Lumpur in February-May 2020 and tested combined oro-nasopharyngeal swabs with the NxTAG Respiratory Pathogen Panel (Luminex) and Allplex RV Essential (Seegene) assays. Forty-five negative samples further underwent viral metagenomics analysis.

Results

Of the 198 samples, 74 (37.4%) had respiratory pathogens, including 56 (28.3%) with SARS-CoV-2 and 18 (9.1%) positive for other respiratory pathogens. There were five (2.5%) SARS-CoV-2 co-infections, all with rhinovirus/enterovirus. Three samples (6.7%; 3/45) had viruses identified by metagenomics, including one case of enterovirus D68 and one of Saffold virus genotype 6 in a patient requiring ICU care. Most of the COVID-19 patients (91.1%; 51/56) had mild symptoms but 5.4% (3/56) died.

Conclusion

During the early COVID-19 period, common respiratory viruses other than SARS-CoV-2 only accounted for 9.1% of hospitalization cases with ARI and co-infections with SARS-CoV-2 were rare. Continued surveillance is important to understand the impact of COVID-19 and its associated public health control measures on circulation of other respiratory viruses. Metagenomics can identify unexpected or rare pathogens, such as Saffold virus, which is rarely described in adults.

Influenza in Malaysian adult patients hospitalized with community-acquired pneumonia, acute exacerbation of chronic obstructive pulmonary disease or asthma: a multicenter, active surveillance study

Background

Available data on influenza burden across Southeast Asia are largely limited to pediatric populations, with inconsistent findings.

Methods

We conducted a multicenter, hospital-based active surveillance study of adults in Malaysia with community-acquired pneumonia (CAP), acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and acute exacerbation of asthma (AEBA), who had influenza-like illness ≤10 days before hospitalization. We estimated the rate of laboratory-confirmed influenza and associated complications over 13 months (July 2018–August 2019) and described the distribution of causative influenza strains. We evaluated predictors of laboratory-confirmed influenza and severe clinical outcomes using multivariate analysis.

Results

Of 1106 included patients, 114 (10.3%) were influenza-positive; most were influenza A (85.1%), with A/H1N1pdm09 being the predominant circulating strain during the study following a shift from A/H3N2 from January–February 2019 onwards. In multivariate analyses, an absence of comorbidities (none versus any comorbidity [OR (95%CI), 0.565 (0.329–0.970)], p = 0.038) and of dyspnea (0.544 (0.341–0.868)], p = 0.011) were associated with increased risk of influenza positivity. Overall, 184/1106 (16.6%) patients were admitted to intensive care or high-dependency units (ICU/HDU) (13.2% were influenza positive) and 26/1106 (2.4%) died (2.6% were influenza positive). Males were more likely to have a severe outcome (ICU/HDU admission or death).

Conclusions

Influenza was a significant contributor to hospitalizations associated with CAP, AECOPD and AEBA. However, it was not associated with ICU/HDU admission in this population.

Study registration, NMRR ID: NMRR-17-889-35,174.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06360-9.

Comparative global epidemiology of influenza, respiratory syncytial and parainfluenza viruses, 2010-2015

OBJECTIVES

To improve our understanding of the global epidemiology of common respiratory viruses by analysing their contemporaneous incidence at multiple sites.

METHODS

2010-2015 incidence data for influenza A (IAV), influenza B (IBV), respiratory syncytial (RSV) and parainfluenza (PIV) virus infections were collected from 18 sites (14 countries), consisting of local (n = 6), regional (n = 9) and national (n = 3) laboratories using molecular diagnostic methods. Each site submitted monthly virus incidence data, together with details of their patient populations tested and diagnostic assays used.

RESULTS

For the Northern Hemisphere temperate countries, the IAV, IBV and RSV incidence peaks were 2-6 months out of phase with those in the Southern Hemisphere, with IAV having a sharp out-of-phase difference at 6 months, whereas IBV and RSV showed more variable out-of-phase differences of 2-6 months. The tropical sites Singapore and Kuala Lumpur showed fluctuating incidence of these viruses throughout the year, whereas subtropical sites such as Hong Kong, Brisbane and Sydney showed distinctive biannual peaks for IAV but not for RSV and PIV.

CONCLUSIONS

There was a notable pattern of synchrony of IAV, IBV and RSV incidence peaks globally, and within countries with multiple sampling sites (Canada, UK, Australia), despite significant distances between these sites.

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.