A measles IgM rapid diagnostic test to address challenges with national measles surveillance and response in Malaysia.

INTRODUCTION: A lateral flow rapid diagnostic test (RDT) enables detection of measles specific immunoglobulin M (IgM) antibody in serum, capillary blood, and oral fluid with accuracy consistent with enzyme immunoassay (EIA). The objectives of the study were: 1) to assess measles RDT inter-reader agreement between two clinic staff; 2) to assess the sensitivity and specificity of the measles RDT relative to standard surveillance testing in a low transmission setting; 3) to evaluate the knowledge, attitudes, and practices of staff in clinics using the RDT; and 4) to assess the impact of RDT testing on the measles public health response in Malaysia. MATERIALS AND METHODS: The clinic-based prospective evaluation included all suspected measles cases captured by routine measles surveillance at 34 purposely selected clinics in 15 health districts in Malaysia between September 2019 and June 2020, following day-long regional trainings on RDT use. Following informed consent, four specimens were collected from each suspected case, including those routinely collected for standard surveillance [serum for EIA and throat swabs for quantitative reverse transcriptase polymerase chain reaction (RT-qPCR)] together with capillary blood and oral fluid tested with RDTs during the study. RDT impact was evaluated by comparing the rapidity of measles public health response between the pre-RDT implementation (December 2018 to August 2019) and RDT implementation periods (September 2019 to June 2020). To assess knowledge, attitudes, and practices of RDT use, staff involved in the public health management of measles at the selected sites were surveyed. RESULTS: Among the 436 suspect cases, agreement of direct visual readings of measles RDT devices between two health clinic staff was 99% for capillary blood (k = 0.94) and 97% for oral fluid (k = 0.90) specimens. Of the total, 45 (10%) were positive by measles IgM EIA (n = 44, including five also positive by RT-qPCR) or RT-qPCR only (n = 1), and 38 were positive by RDT (using either capillary blood or oral fluid). Using measles IgM EIA or RT-qPCR as reference, RDT sensitivity using capillary blood was 43% (95% CI: 30%-58%) and specificity was 98% (95% CI: 96%-99%); using oral fluid, sensitivity (26%, 95% CI: 15%-40%) and specificity (97%, 95% CI: 94%-98%) were lower. Nine months after training, RDT knowledge was high among staff involved with the public health management of measles (average quiz score of 80%) and was highest among those who received formal training (88%), followed by those trained during supervisory visits (83%). During the RDT implementation period, the number of days from case confirmation until initiation of public response decreased by about 5 days. CONCLUSION: The measles IgM RDT shows >95% inter-reader agreement, high retention of RDT knowledge, and a more rapid public health response. However, despite ≥95% RDT specificity using capillary blood or oral fluid, RDT sensitivity was <45%. Higher-powered studies using highly specific IgM assays and systematic RT-qPCR for case confirmation are needed to establish the role of RDT in measles elimination settings.

Sero-Prevalence of Covid-19 among workers in Malaysia

From the beginning of the pandemic in Feb 2020, Malaysia has been through 4 waves of outbreak, the magnitude of each wave is several orders larger than the preceding one. By the end of the fourth wave in October 2021, Malaysia has among the highest death toll in Asia, cumulative incidence of confirmed cases has reached 7.0% (>30% in Klang Valley). However it remains uncertain what is the true proportion of the population infected. We conducted a sero-survey on 1078 workers from 17 worksites in Klang Valley and Perak between July and September 2021. We tested them for SARS-CoV-2-specific antibodies using Ecotest, a lateral flow immunoassay (LFIA). The ability of antibody testing to detect prior infection depends on the assay and sero-reversion. We therefore adjusted the prevalence estimates to correct for potential misclassification bias due to the use of LFIA and sero-reversion using test sensitivity and specificity results estimated from an independent validation study. The mean age of the workers was 32 years, 89% were male and migrant workers comprised 81% of all subjects, 59% the subjects were from Klang valley. 33% of workers had prior RT-PCR confirmed Covid-19 infections. We estimated 82.2 percent of workers had been infected by Covid-19 by July-September 2021. Prevalence was 99.9% among migrant workers and 12.1% among local workers. Klang Valley, the most industrialized region in Malaysia where most migrant workers are found, had 100% prevalence, giving an infection-to-case ratio (ICF) of [~]3. Our sero-prevalence results show that the incidence of Covid19 is extremely high among migrant workers in Malaysia, consistent with findings from other countries such as Kuwait and Singapore which also hosted large number of migrant workers.

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

Influenza seasonality in equatorial countries is little understood. Seasonal and alert influenza thresholds were determined for Malaysia, using laboratory-based data obtained from the Malaysia Influenza Surveillance System and a major teaching hospital, from 2011 to 2016. Influenza was present year-round, with no clear annual seasons. Variable periods of higher transmission occurred inconsistently, in November to December, January to March, July to September, or a combination of these. These coincide with seasons in the nearby southeast Asian countries or winter seasons of the northern and southern hemispheres. Changes in the predominant circulating influenza type were only sometimes associated with increased transmission. The data can provide public health interventions such as vaccines.