Factors associated with breakthrough varicella
| Factor | n | Contact history | Breakthrough varicella | Adjusted OR | 95% CI |
|---|---|---|---|---|---|
| Vaccination age3-150 | |||||
| ⩽ 14 months | 60 | 26 | 10 | 2.30 | 1.69 to 2.90 |
| > 14 months | 108 | 56 | 8 | 1 | |
| Vaccine titre3-151 | |||||
| Group 1 | 43 | 18 | 3 | NS | |
| Group 2 | 42 | 18 | 8 | 2.13 | 1.54 to 2.73 |
| Group 3 | 40 | 22 | 2 | NS | |
| Group 4 | 43 | 24 | 5 | NS | |
| VzAb3-150 3-152 | |||||
| < 64 | 67 | 25 | 5 | 1 | |
| ⩾ 64 | 101 | 57 | 13 | NS | |
| Sex | |||||
| Female | 80 | 36 | 8 | NS | |
| Male | 88 | 46 | 10 | 1 | |
| Follow up period (months) | |||||
| ⩽ 37.175 | 84 | 39 | 9 | 1 | |
| > 37.175 | 84 | 43 | 9 | NS | |
↵3-150 A cut off age of 14 months and a titre of 1/64 were used as these were the medians for the cohort.
↵3-151 Reference category for vaccine titre in each case in the multiple logistic regression was the other titres (for example, reference category for group 1 in the comparison was groups 2–4).
↵3-152 VzAb denotes the varicella specific antibody titre six weeks after immunisation.14