Figure 1From: Longitudinal field studies reveal early infection and persistence of influenza A virus in piglets despite the presence of maternally derived antibodiesPercentage of IAV-positive litters in the four batches of the three herds. The columns present the percentage of positive individuals in each batch at each sampling time (week 1, week 3, week 5 and weeks 10–12) for each of the three herds.Back to article page