Long duration of immunity against a type 1 heterologous PRRS virus challenge in pigs immunised with a novel PRRS MLV vaccine: a randomised controlled study

Table 2 Mean histological lung lesion scores at necropsy

	Histological lung lesion score (mean)
Study	Group	n	Mean	95% CI	Median (IQR)	p-value^*
20-week	1	22	13.0	4.0–18.0	9.5 (14.0)	0.0065
20-week	2	20	24.7	16.0–35.0	23.0 (20.5)	0.0065
24-week	1	20	7.3	2.0–10.0	7.0 (8.5)	< 0.0001
24-week	2	19	20.6	12.0–28.0	19.0 (16.0)	< 0.0001
26-week	1	21	6.6	3.0–8.0	6.0 (5.0)	< 0.0001
26-week	2	20	20.2	15.0–23.0	19.5 (10.0)	< 0.0001

CI distribution free confidence interval of the median, IQR interquartile range, MLV modified live virus, n number of pigs included in analysis, PRRS porcine reproductive and respiratory syndrome
Group 1 = PRRS 94881 MLV vaccinated; Group 2 = challenge controls
^*p-values were calculated using the Wilcoxon-Mann-Whitney test

ISSN: 2055-5660