Fig 2
Level of protection against tetanus and diphtheria. Tetanus- a and diphtheria- b specific Ab concentrations from young and elderly adults were measured by ELISA. A concentration above 0.1 IU/ml was considered as protective. Frequencies of protected (grey) and unprotected (black) individuals are shown. Plasma samples were collected before (day 0_2010), 4 weeks after (day 28_2010) as well as 5 years after (2015) the booster shot. Chi-squared test was applied for statistical analysis. * x 2 = 4.36 (x2 crit = 3.84)