Nonpharmaceutical Interventions Used to Control COVID-19 Reduced Seasonal Influenza Transmission in China

Abstract To suppress the ongoing COVID-19 pandemic, the Chinese government has implemented nonpharmaceutical interventions (NPIs). Because COVID-19 and influenza have similar means of transmission, NPIs targeting COVID-19 may also affect influenza transmission. In this study, the extent to which NPIs targeting COVID-19 have affected seasonal influenza transmission was explored. Indicators of seasonal influenza activity in the epidemiological year 2019–2020 were compared with those in 2017–2018 and 2018–2019. The incidence rate of seasonal influenza reduced by 64% in 2019–2020 (P < .001). These findings suggest that NPIs aimed at controlling COVID-19 significantly reduced seasonal influenza transmission in China.

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The Effectiveness of Governmental Nonpharmaceutical Interventions Against COVID-19 On The Control of Seasonal Influenza Transmission: An Ecological Study

10.21203/rs.3.rs-1197712/v1 ◽

2022 ◽

Author(s):

Zekai Qiu ◽

Zicheng Cao ◽

Min Zou ◽

Kang Tang ◽

Chi Zhang ◽

...

Keyword(s):

Seasonal Influenza ◽

International Travel ◽

School Closure ◽

Gradient Boosting ◽

Positive Interaction ◽

Precise Control ◽

Extreme Gradient Boosting ◽

Influenza Transmission ◽

Nonpharmaceutical Interventions ◽

Suppression Index

Abstract Background: A range of strict nonpharmaceutical interventions (NPIs) had been implemented in many countries to combat the COVID-19 pandemic. These NPIs might also be effective in controlling the seasonal influenza virus, which share the same transmission path with SARS-CoV-2. The aim of this study is to evaluate the effect of different NPIs for control of seasonal influenza.Methods: Data on 14 NPIs implemented in 33 countries and corresponding data on influenza virologic surveillance were collected. The influenza suppression index was calculated as the difference between the influenza-positive rate during its decline period from 2019 to 2020 and that during influenza epidemic seasons in the previous 9 years. A machine learning model was developed by using extreme gradient boosting tree (XGBoost) regressor to fit NPI data and influenza suppression index. SHapley Additive exPlanations (SHAP) was used to characterize NPIs in suppressing influenza.Results: Gathering limitation contributed the most (37.60%) among all NPIs in suppressing influenza transmission in the 2019-2020 influenza season. The top three effective NPIs were gathering limitation, international travel restriction, and school closure. Regarding the three NPIs, their intensity threshold to generate effect were restrictions on the size of gatherings less than 1000 people, travel bans on all regions or total border closure, and closing only some categories of schools, respectively. There was a strong positive interaction effect between mask wearing requirement and gathering limitation, whereas merely implementing mask wearing requirement but ignoring other NPIs would dilute mask wearing requirement’s effectiveness in suppressing influenza.Conclusions: Gathering limitation, travel bans on all regions or total border closure, and closing some levels of schools are the most effective NPIs to suppress influenza transmission. Mask wearing requirement is advised to be combined with gathering limitation and other NPIs. Our findings could facilitate the precise control of future influenza epidemics and potential pandemics.

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Effects of School Holidays on Seasonal Influenza in South Korea, 2014–2016

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa179 ◽

2020 ◽

Vol 222 (5) ◽

pp. 832-835 ◽

Cited By ~ 6

Author(s):

Sukhyun Ryu ◽

Sheikh Taslim Ali ◽

Benjamin J Cowling ◽

Eric H Y Lau

Keyword(s):

South Korea ◽

Seasonal Influenza ◽

School Closure ◽

Surveillance Data ◽

Influenza Surveillance ◽

School Closures ◽

School Aged Children ◽

Severe Influenza ◽

Influenza Transmission

Abstract School closures are considered as a potential nonpharmaceutical intervention to mitigate severe influenza epidemics and pandemics. In this study, we assessed the effects of scheduled school closure on influenza transmission using influenza surveillance data before, during, and after spring breaks in South Korea, 2014–2016. During the spring breaks, influenza transmission was reduced by 27%–39%, while the overall reduction in transmissibility was estimated to be 6%–23%, with greater effects observed among school-aged children.

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Associations between seasonal influenza and meteorological parameters in Costa Rica, Honduras and Nicaragua

Geospatial health ◽

10.4081/gh.2015.372 ◽

2015 ◽

Vol 10 (2) ◽

Cited By ~ 14

Author(s):

Radina P. Soebiyanto ◽

Wilfrido A. Clara ◽

Jorge Jara ◽

Angel Balmaseda ◽

Jenny Lara ◽

...

Keyword(s):

Costa Rica ◽

Central America ◽

Seasonal Influenza ◽

Meteorological Parameters ◽

Correlation Coefficients ◽

Tropical Rainfall Measuring Mission ◽

Specific Humidity ◽

Considerable Proportion ◽

Influenza Activity ◽

Land Data Assimilation System

Seasonal influenza affects a considerable proportion of the global population each year. We assessed the association between subnational influenza activity and temperature, specific humidity and rainfall in three Central America countries, <em>i.e.</em> Costa Rica, Honduras and Nicaragua. Using virologic data from each country’s national influenza centre, rainfall from the Tropical Rainfall Measuring Mission and air temperature and specific humidity data from the Global Land Data Assimilation System, we applied logistic regression methods for each of the five sub-national locations studied. Influenza activity was represented by the weekly proportion of respiratory specimens that tested positive for influenza. The models were adjusted for the potentially confounding co-circulating respiratory viruses, seasonality and previous weeks’ influenza activity. We found that influenza activity was proportionally associated (P<0.05) with specific humidity in all locations [odds ratio (OR) 1.21-1.56 per g/kg], while associations with temperature (OR 0.69-0.81 per °C) and rainfall (OR 1.01-1.06 per mm/day) were location-dependent. Among the meteorological parameters, specific humidity had the highest contribution (~3-15%) to the model in all but one location. As model validation, we estimated influenza activity for periods, in which the data was not used in training the models. The correlation coefficients between the estimates and the observed were ≤0.1 in 2 locations and between 0.6-0.86 in three others. In conclusion, our study revealed a proportional association between influenza activity and specific humidity in selected areas from the three Central America countries.

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Masks in a Post COVID-19 World: A Better Alternative to Curtailing Influenza?

10.1101/2021.07.03.21259943 ◽

2021 ◽

Author(s):

Henri Froese ◽

Angel G. A. Prempeh

Keyword(s):

Respiratory Diseases ◽

Seasonal Influenza ◽

Transmission Rate ◽

Model Fit ◽

Respiratory Specimen ◽

The Past ◽

Hypothetical Scenario ◽

Influenza Transmission ◽

Influenza Vaccinations ◽

The Impact

Over the course of the coronavirus pandemic, it has become apparent that non-pharmaceutical interventions such as masks and social distancing are of great help in mitigating the transmission of airborne infectious diseases. Additionally, data from respiratory specimen analysis from the past year show that current mask mandates established for COVID-19 have inadvertently reduced the rates of other respiratory diseases, including influenza. Thus, the question arises as to whether comparatively mild measures should be kept in place after the pandemic to reduce the impact of influenza. In this study, we employed a series of differential equations to simulate past influenza seasons, assuming people wore face masks. This was achieved by introducing a variable to account for the efficacy and prevalence of masks and then analyzing its impact on influenza transmission rate in an SEIR model fit to the actual past seasons. We then compared influenza rates in this hypothetical scenario with the actual rates over the seasons. Our results show that several combinations of mask efficacy and prevalence can significantly reduce the burden of seasonal influenza. Particularly, our simulations suggest that a minority of individuals wearing masks greatly reduce the number of influenza infections. Considering the efficacy rates of masks and the relatively insignificant monetary cost, we highlight that it may be a viable alternative or complement to influenza vaccinations. We conclude with a brief discussion of our results and other practical aspects.

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