STUDY DESIGN: For this study, data of weekly new cases of influenza and COVID-19 were obtained from official platforms for non-parametric statistical analysis.
METHODS: This study compared the influenza occurrences before and after the onset of COVID-19 using the Mann-Whitney U-test and explored Spearman's correlations between COVID-19 and influenza incidences after the onset of COVID-19.
RESULTS: It shows that influenza incidences before and after the onset of COVID-19 were significantly different and that influenza cases have significantly reduced after the onset of COVID-19. The weekly cases of influenza and COVID-19 were significantly and negatively correlated.
CONCLUSIONS: This study underscores the co-benefits of COVID-19 control measures and alleviates the concern for the risk of COVID-19 and influenza co-infection.
METHODS: A modified susceptible-exposed-infectious-recovered compartmental model was developed that included two sequential incubation and infectious periods, with stratification by clinical state. The model was further stratified by age and incorporated population mobility to capture NPIs and micro-distancing (behaviour changes not captured through population mobility). Emerging variants of concern (VoC) were included as an additional strain competing with the existing wild-type strain. Several scenarios that included different vaccination strategies (i.e. vaccines that reduce disease severity and/or prevent infection, vaccination coverage) and mobility restrictions were implemented.
RESULTS: The national model and the regional models all fit well to notification data but underestimated ICU occupancy and deaths in recent weeks, which may be attributable to increased severity of VoC or saturation of case detection. However, the true case detection proportion showed wide credible intervals, highlighting incomplete understanding of the true epidemic size. The scenario projections suggested that under current vaccination rates complete relaxation of all NPIs would trigger a major epidemic. The results emphasise the importance of micro-distancing, maintaining mobility restrictions during vaccination roll-out and accelerating the pace of vaccination for future control. Malaysia is particularly susceptible to a major COVID-19 resurgence resulting from its limited population immunity due to the country's historical success in maintaining control throughout much of 2020.