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Volume 32, Number 8—August 2026
Research
Occupationally Exposed and General Population Antibody Profiles to Influenza A Viruses Circulating in Swine as Indication of Zoonotic Risk
Figure 3

Figure 3. Box and whisker plots of log2 transformed hemagglutination inhibition (HI) titers among participants in 4 human cohorts against contemporary swine H1 and H3 influenza A virus strains in study of occupationally exposed and general population antibody profiles to influenza A viruses circulating in swine as indication of zoonotic risk. A) Veterinarians (n = 51); B) farm employees (n = 47); C) Philadelphia general population cohort (n = 40); D) Hong Kong general population cohort (n = 40). Box plots show median log2 transformed HI titers on the x-axis, test strains on the y-axis, interquartile ranges, and outliers. Purple dots represent the geometric mean log2 transformed HI titers/10. Gray box plots represent responses against human seasonal influenza vaccine strains, and white box plots represent responses against swine strains. Reverse-transformed HI geometric mean titers in purple and percentages of positive persons in black are shown next to virus names on each panel. The gray dotted line indicates the HI titer threshold of 40 (log2 scale of 2).