The Infectious Diseases Society of America (IDSA) recently re-issued the clinical practice guidelines for seasonal influenza, last updated in 2009. The latest publication addresses updates in diagnosis, treatment, prevention and outbreak management of seasonal influenza, commonly known as the flu.

In the US, GlobalData epidemiologists forecast the number of diagnosed incident cases of seasonal influenza by source of diagnosis in 2018; approximately 87% of cases were diagnosed as outpatients, 9% were lab-confirmed, and 3% were inpatients (as shown in Figure 1). GlobalData epidemiologists believe that these new guidelines will likely affect the number of diagnosed incident cases of seasonal flu in the US, as well as change the distribution of cases by source of diagnosis.

Key changes to the guidelines include recommendations for diagnostic testing and high-risk populations. The new guidelines advise clinicians to use rapid molecular assays over rapid influenza diagnostic tests (RIDTs) in outpatients; this will improve both flu detection and diagnosis, as RIDTs often produce false-negative results.

Figure 1: US, Diagnosed Incident Cases of Seasonal Influenza by Source of Diagnosis, Both Sexes, All Ages, N, 2018

Seasonal flu guidance

Source: GlobalData. © GlobalData

Additionally, the guidelines incorporate the approval of new antiviral drugs that can reduce the severity and duration of seasonal flu. IDSA recommends prompt administration of antiviral treatment in high-risk populations (immunocompromised, elderly, pregnant women, infants) to reduce influenza-related complications and thus hospitalization.

The impact of these new recommendations will likely be twofold: one, an increase in the number of diagnosed outpatients due to more accurate testing; and two, a decrease in flu-related hospitalizations due to early antiviral treatment in high-risk populations. GlobalData epidemiologists suggest further analysis of surveillance data over the next several flu seasons to more clearly assess and characterize the impact of these new guidelines.