Time to add influenza to COVID-19 pandemic dashboards
The novel coronavirus (COVID-19) pandemic had devastating effects in the fall and winter of 2020-2021; at the same time, influenza rates have reached an all-time low. The period September 2020 to September 2021 saw the United States register just over 300 positive influenza test results from public health laboratories. This contrasts sharply with the 2019-2020 season, which recorded nearly 47,000 positive flu test results. Part of this decrease may be due to observation and reporting bias, as SARS-CoV-2 has preoccupied testing efforts. Nonetheless, this represented a stunning reduction in reported influenza cases, consistent with contemporary global influenza activity.
The general view is that the COVID-19 pandemic has replaced much of the typical influenza season through a combination of community measures (eg, non-pharmaceutical interventions), personal choice and differences in population sensitivity. . But this event is transient for influenza and other respiratory threats. In 2008-2010, well over half of influenza isolates were influenza A (H1N1) pdm09, the pandemic strain. The non-pandemic influenza strain rebounded during the 2010-11 season, and the influenza strains observed thereafter were increasingly pleomorphic, of varying types.
Eventually, the flu will return with a vengeance. Statements throughout the pandemic as to whether COVID-19 was more or less severe and problematic than seasonal flu completely missed the point. COVID-19 is a deadly and existential threat. However, on average, nearly 1 in 10 people in the United States suffer from the flu each year. During the relatively mild 2019-2020 influenza season, influenza in the United States caused an estimated 400,000 hospitalizations and 22,000 deaths. Like other cosmopolitan infections â those that occur around the world and pervasively â the indirect impacts of influenza are often underestimated. People with complications from a chronic illness, sequelae of acute infection, or undiagnosed acute influenza leading to hospitalization and death are only partially accounted for in the methods of determining the impact of influenza. There is a whole science built around the challenges of making such estimates.
The need to manage the flu is reason enough to pay close attention to its activity this year. Additionally, adding influenza and other respiratory disease activity and their consequences (e.g., hospitalizations, deaths) to the dashboards of the COVID-19 pandemic would quickly alert the public and decision-makers that community-based respiratory prevention measures require special attention. Take, for example, our experience last summer with respiratory syncytial virus (RSV). RSV, which primarily affects young children and vulnerable adults, also experienced a decline during its 2020-2021 season. However, in mid-2021, RSV rates returned to the very high levels seen in late 2019, preceding the multitude of COVID-19 spikes across the country seen weeks to months later. In Table 1, below, COVID-19 case rates are juxtaposed with RSV and influenza case rates, demonstrating the utility of an integrated communicable respiratory disease risk assessment to provide early warning and an opportunity to increase vigilance against COVID-19.
Figure 1: Respiratory disease cases by week, week 49 of 2019 â week 36 of 2021
Source: Generated by authors using public data from the Centers for Disease Control and Prevention of Influenza, COVID-19, and Respiratory Syncytial Virus Surveillance Programs.
The rebound in pervasive respiratory threats is a sentinel of the challenges of the current pandemic, especially in the context of insufficient vaccination rates, inadequate access to testing and reluctance to what measures each community can use – wearing masks , physical and social distancing, personal and environmental hygiene, proactive surveillance with case tracing, contact tracing for previous and subsequent cases, especially in new variants, and the appropriate use of isolation and quarantine.
Adding influenza activity and potentially other respiratory illnesses and their consequences (eg, hospitalizations, deaths) to the dashboards of the COVID-19 pandemic would allow the public and policy makers to be notified that Community respiratory prevention and mitigation measures require special attention. It could also indicate the value of integrating testing for influenza and other respiratory illnesses into the asymptomatic and asymptomatic screening and surveillance triggered by influenza-like illness (ILI) during the pandemic. Together, integrated testing and reporting would also help policymakers determine when it’s COVID-19 or the flu or both that is impacting communities, as each requires individual and overlapping control measures. Many of the molecular platforms available for clinical COVID-19 diagnostic testing are multiplexed with influenza, RSV, and in some cases, larger respiratory panels. However, most of the testing methods used for large-scale asymptomatic case detection (for example, single-target PCR tests used for school and workplace screening programs) or environmental surveillance only detect SARS-CoV. -2, leaving an opportunity for proactive community surveillance of common respiratory viruses using existing infrastructure and program samples.
There are related surrogates that could also be used in risk assessment and communication. Increased absenteeism from school or work is a useful trigger to take a closer look at whether respiratory illnesses are underestimated in this context. Imagine every website and school and workplace entrance with the statement: “X days since a case of COVID-19, Y days since respiratory illness, Z days since someone missed their job because of he was sick. We should learn lessons from the workplace safety community on how to cultivate awareness of what is going on around us and what it tells us about the threats and associated susceptibilities.
As we enter the 2021-2022 influenza season, we should take stock of what we are doing to reduce COVID-19 and the overall risk of respiratory illness and build on our continued experience with the flu and other threats. respiratory systems to indicate when increased vigilance in managing the risk of a COVID-19 pandemic is needed.
Opinions are those of the authors and not necessarily those of the State of Nebraska or any agency.