Table 2. Investigated effects of age group, sampling period and vaccination on titre using the final Tobit regression model.

Increase in titre:	Factor	95% CI
between pre- and post-pandemic period in age group 18-32	10.2	5.0–20.7
between pre- and post-pandemic period in age group 33–52	6.2	3.3–11.9
between pre- and post-pandemic period in age group ≥53	2.4	1.3–4.3
if vaccinated with seasonal vaccine	1.9	1.3–2.7

The table shows increase in uncensored titre