Influenza activity in the Eastern Mediterranean Region (EMR) in 2020-2021 amidst the COVID-19 pandemic

Abstract

Introduction: A global reduction in influenza virus activity during the COVID-19 pandemic has been observed, including in the Eastern Mediterranean Region (EMR). However, these changes have not been thoroughly evaluated scientifically in the EMR.

Objective: We aim to present data on seasonal influenza activity during the pre-pandemic period (2016-2019) and compare it to the pandemic period (2020-2021) in EM countries.

Methods: Epidemiological and virological influenza surveillance data were retrieved from both WHO FluNet and EMFLU networks. Four pre-pandemic analytical periods were used in the comparative analysis. We compiled and calculated weekly aggregated epidemiological data on the number of enrolled patients, number of tested specimens and number of positive influenza specimens.

Results: 19 out of the 22 countries of the EMR have functioning sentinel influenza surveillance systems, and these countries report the influenza data to WHO through FluNet and EMFLU. The number of enrolled patients and tested specimens increased gradually from 51 384 and 50 672, respectively, in 2016-2017 analytical period to 194 049 enrolled patients and 124 697 tested specimens in 2019-2020. A decrease has been witnessed in both enrolled patients and tested specimens in 2020-2021 'pandemic period' (166 576 and 44 764, respectively). By comparing influenza activity of analytical period 2020-2021 with that of 2016-2019 analytical periods, we found that there has been a decrease in influenza positivity rate in the EMR by 89%.

Conclusion: The implementation of non-pharmaceutical interventions to control the COVID-19 pandemic may have also impacted the spread of influenza viruses. The low circulation of influenza viruses during 2020-2021 and the associated potential immunity gap may result in increased transmission and severity of post-pandemic influenza seasons. This necessitates high vigilance to continuous data and virus sharing to monitor circulating viruses in a timely fashion to reduce the intensity and severity of future influenza epidemics.

Keywords: COVID-19; respiratory infections.

Figure 1

Number of enrolled patients, tested specimens and per cent positive influenza specimens by analytical period, Eastern Mediterranean countries, from 2016–2017 until 2021–2022 (up to week 33).

Figure 2

Number of specimens tested and percentage of positive tests for influenza, by analytical period, Eastern Mediterranean Region, from 2016–2017 until 2021–2022 (up to week 33). W, week.

Figure 3

Percentage of specimens testing positive for influenza viruses, by week (W), Eastern Mediterranean Region, from 2016–2017 until 2021–2022 (up to week 33).

Figure 4

Percentage of subtyped influenza viruses by analytical period, Eastern Mediterranean Region, from 2016–2017 until 2021–2022 (up to week 33).

Figure 5

Number of specimens by subtyped influenza viruses and percentage of specimens testing positive for influenza viruses, by analytical periods, Eastern Mediterranean Region, from 2016–2017 until 2021–2022 (up to week 33). W, week.