Seasonal influenza is known to be a significant burden to patients and the health care system. Understanding how this highly contagious infection is spread, particularly among family members, is important for quantifying the burden of flu and potential impact of upcoming therapeutic agents that limit transmission. This study used real world US claims data to understand families medical care seeking behavior for flu infection and the relationship between family size and days families are burdened with flu within their household.
This was a retrospective analysis of US commercial claims data from the 2014-2016 flu seasons. Patients with enrolled family members and a diagnosis code for flu were identified and required to have continuous coverage during each influenza episode (defined as 14 days from the first flu case in a family).
We identified 1,224,808 primary cases of flu among families of 2 or more members. The median family size was 4 members (25th, 75th percentiles=3, 4). Of these families with at least one case of flu, 119,883 (9.8%) had additional member(s) who sought care for flu within the same flu episode. 70.8% (84,903) of these cases occurred within 3 days after the first members claim for influenza (figure 1).
Increased family size was associated with a higher percentage of families where flu spread to other members of the family beyond the first member diagnosed (6.4% of families of size 2 or 3 versus 12.6% of families of size 4 or greater, p-value < 0.001). Family size was also positively correlated with the number of days between the first and last flu-related office visit within a family (Spearman coefficient=0.09, p-value< 0.001). The majority of family members who sought care for flu were children (n= 810,867; 59.5%), followed by employees (n=323,277; 23.7%) and their spouses (n=228,775; 16.8%).
In data for the last 3 available flu seasons, we identified a significant number of secondary cases of flu among families with a primary case. Larger families had higher likelihood for subsequent flu infections and more number of days for dealing with flu. Transmission of flu between family members represents a large burden on the healthcare system and reveals an unmet need for treatment options that limit transmission.
D. Sheinson, Roche: Employee , Salary .
D. Keebler, Roche: Employee , Salary .
D. Moawad, Roche: Employee , Salary .