Application of the Time Derivative (TD) Method for Early Alert of Influenza Epidemics

BACKGROUND

In order to minimize the spread of seasonal influenza epidemic to communities worldwide, the Korea Disease Control and Prevention Agency has issued an influenza epidemic alert using the influenza epidemic threshold formula based on the results of the influenza-like illness (ILI) rate. However, unusual changes have occurred in the pattern of respiratory infectious diseases, including seasonal influenza, after the coronavirus disease 2019 (COVID-19) pandemic. As a result, the importance of detecting the onset of an epidemic earlier than the existing epidemic alert system is increasing. Accordingly, in this study, the Time Derivative (TD) method was suggested as a supplementary approach to the existing influenza alert system for the early detection of seasonal influenza epidemics.

METHODS

The usefulness of the TD method as an early epidemic alert system was evaluated by applying the ILI rate for each week during past seasons when seasonal influenza epidemics occurred, ranging from the 2013-2014 season to the 2022-2023 season to compare it with the issued time of the actual influenza epidemic alert.

RESULTS

As a result of applying the TD method, except for the two seasons (2020-2021 season and 2021-2022 season) that had no influenza epidemic, an influenza early epidemic alert was suggested during the remaining seasons, excluding the 2017-2018 and 2022-2023 seasons.

CONCLUSION

The TD method is a time series analysis that enables early epidemic alert in real-time without relying on past epidemic information. It can be considered as an alternative approach when it is challenging to set an epidemic threshold based on past period information. This situation may arise when there has been a change in the typical seasonal epidemic pattern of various respiratory viruses, including influenza, following the COVID-19 pandemic.

Anti-rheumatic colchicine phytochemical exhibits potent antiviral activities against avian and seasonal Influenza A viruses (IAVs) via targeting different stages of IAV replication cycle

BACKGROUND

The continuous evolution of drug-resistant influenza viruses highlights the necessity for repurposing naturally-derived and safe phytochemicals with anti-influenza activity as novel broad-spectrum anti-influenza medications.

METHODS

In this study, nitrogenous alkaloids were tested for their viral inhibitory activity against influenza A/H1N1 and A/H5N1 viruses. The cytotoxicity of tested alkaloids on MDCK showed a high safety range (CC50 > 200 µg/ml), permitting the screening for their anti-influenza potential.

RESULTS

Herein, atropine sulphate, pilocarpine hydrochloride and colchicine displayed anti-H5N1 activities with IC50 values of 2.300, 0.210 and 0.111 µg/ml, respectively. Validation of the IC50 values was further depicted by testing the three highly effective alkaloids, based on their potent IC50 values against seasonal influenza A/H1N1 virus, showing comparable IC50 values of 0.204, 0.637 and 0.326 µg/ml, respectively. Further investigation suggests that colchicine could suppress viral infection by primarily interfering with IAV replication and inhibiting viral adsorption, while atropine sulphate and pilocarpine hydrochloride could directly affect the virus in a cell-free virucidal effect. Interestingly, the in silico molecular docking studies suggest the abilities of atropine, pilocarpine, and colchicine to bind correctly inside the active sites of the neuraminidases of both influenza A/H1N1 and A/H5N1 viruses. The three alkaloids exhibited good binding energies as well as excellent binding modes that were similar to the co-crystallized ligands. On the other hand, consistent with in vitro results, only colchicine could bind correctly against the M2-proton channel of influenza A viruses (IAVs). This might explicate the in vitro antiviral activity of colchicine at the replication stage of the virus replication cycle.

CONCLUSION

This study highlighted the anti-influenza efficacy of biologically active alkaloids including colchicine. Therefore, these alkaloids should be further characterized in vivo (preclinical and clinical studies) to be developed as anti-IAV agents.

A randomized trial of vitamin D supplementation to prevent seasonal influenza and enterovirus infection in children

PURPOSE

This study aimed to evaluate whether vitamin D supplementation can reduce the incidence of influenza and enterovirus infection in Taiwanese children.

METHODS

This randomized, double-blind, controlled trial included children aged two to five years between April 2018 and October 2019 from daycare centers. All the participants were randomly assigned to a vitamin D supplementation group (2000 IU/day) or placebo group for one month. The primary outcome was the incidence of influenza and enterovirus infection in the following six months, and the secondary outcome was the incidence of influenza and enterovirus infection in the children's household members.

RESULTS

Two hundred and forty-eight children participated. The vitamin D group showed a relative risk reduction of 84% against influenza compared to the placebo group but did not reach statistical significance. Kaplan-Meier curves revealed that the placebo group had a higher probability of influenza infection than the vitamin D group (log-rank test, p = 0.055), but the incidence of enterovirus infection was similar between the two groups (p = 0.946) among children. Among children's household members, the incidence of influenza (p = 0.586) and enterovirus infection (p = 0.528) were both similar between the two groups. All children who were tested for serum 25(OH)D levels after vitamin D intervention had 25(OH)D levels above 30 ng/ml CONCLUSION: Vitamin D supplementation may have a small preventative effect against influenza infection but does not affect enterovirus infection among preschool children. A high-dose short-term vitamin D intervention might be a way to elevate children's serum vitamin D levels in the first month of starting kindergarten.

Sunlight and Protection Against Influenza

Recent medical literature suggests that vitamin D supplementation protects against acute respiratory tract infection. Humans exposed to sunlight produce vitamin D directly. This paper investigates how differences in sunlight, as measured over several years across states and during the same calendar week, affect influenza incidence. We find that sunlight strongly protects against getting influenza. This relationship is driven almost entirely by the severe H1N1 epidemic in fall 2009. A 10% increase in relative sunlight decreases the influenza index in September or October by 1.1 points on a 10-point scale. A second, complementary study employs a separate data set to study flu incidence in counties in New York State. The results are strongly in accord.