Table 3 Awareness and knowledge of STDs reported in 14 of the 15 studies included in the review (Continued) Participants who knew that chlamydia can be symptom-free Syphilis Heard of syphilis (identification from list of STDs or direct question) Gonorrhoea 51% in 1986, and 68% in 1988 survey (Andersson-Ellström et al.) [37] 28% in 1986, and 45% in 1988 survey (Andersson-Ellström et al.) [37] 46% (Höglund et al.) [47] 40% in 1986, and 56% in 1988 survey (Andersson-Ellström et al.)** [37] 45.5% among year 9 and 47.0% among year 11 pupils (Garside et al.) [42] 43.4% among year 9 and 45.3% 45% (Garside et al.) [42] among year 11 pupils (Garside et al.) [42] Heard of gonorrhoea (identification from list of 51.0% among year 9 and 53.0% STDs or direct question) among year 11 pupils (Garside et al.) [42] Heard of gonorrhoea (open question - which STDs do you know/have you heard of?) Herpes Heard of herpes (identification from list of STDs 52.4% among year 9 and 75.8% or direct question) among year 11 pupils (Garside et al.) [42] 53.6% among year 9 and 71.7% among year 11 pupils (Garside et al.) [42] 52.4% among year 9 and 60.4% 53% (Garside et al.) [42] among year 11 pupils (Garside ≥ 84% (Tyden et al.) [38] et al.) [42] 98%, 1986 survey (Andersson- Ellström et al.) [37] 50% (Höglund et al.) [47] 59.1% (Garside et al.)*** [42] 90%, 1986 survey (Andersson- Ellström et al.) [37] 56% (Tyden et al.) [38] 64% (Höglund et al.) [47] Samkange-Zeeb et al. BMC Public Health 2011, 11:727 http://www.biomedcentral.com/1471-2458/11/727 Page 8 of 12 * combined figure given for HPV and chlamydia ** statistically significant differences in awareness/knowledge between boys and girls *** statistically significant differences in awareness/knowledge between year 9 and year 11 pupils # Publication in German contact. For the latter mode of transmission, the lowest proportion of correct answers was observed among 16 year old pupils. Generally the proportion of respondents correctly reporting that use of condoms helps protect against contraction of HIV was above 90%. The only exception was in the Russian study conducted by Lunin et al. in 1993, in which only 42% of females and 60% of males were aware of this fact [39]. In the same study, only 15% of the adolescents perceived themselves ‘not at risk’ of contracting HIV (Table 3). Only one study reported asking the adolescents if one can tell by looking at someone if they have HIV, to which 47% responded affirmatively [43]. Awareness and knowledge of chlamydia The proportion of adolescents able to identify chlamydia as an STD from a list of diseases ranged from 34% in the study conducted in England by Garside et al. [42] to 96% in the Swedish study by Andersson-Ellström et al. [22]. In the Garside study, the proportion was higher Heard of herpes (open question - which STDs do you know/have you heard of?) STDs in general Participants who knew that STDs in general can be symptom-free Participants who knew that use of condoms can protect against contraction of STDs in general Subjective rating of risk of contracting an STD in general Reported use of condoms Participants who reported using condoms at first sexual intercourse Participants who reported using condoms at last sexual intercourse 53.8% among year 9 and 60.0% among year 11 pupils (Garside et al.) [42] 64.2% among year 9 and 60.4% 59.7% (Garside et al.) [42] among year 11 pupils (Garside et al.) [42] 15%, 1986 survey (Andersson- Ellström et al.) [37] 34%, 1988 survey (Andersson- Ellström et al.) [37] 100% (Andersson-Ellström et al.) [40] 32%, 1986 survey (Andersson- Ellström et al., 1991) [37] 24%, 1988 survey (Andersson- Ellström et al.) [37] 27%, 1986 survey (Andersson- Ellström et al.) [37] 52%, 1988 survey (Andersson- Ellström et al.) [37] 16%, 1986 survey (Andersson- Ellström et al.) [37] 24%, 1988 survey (Andersson- Ellström et al.) [37] 50% (Tyden et al.) [38] 65% (Gottvall et al.) [46] 40% (Tyden et al.) [38] 65% (Gottvall et al.) [46] 26% (Tyden et al.) [38] 38% (Tyden et al.) [38] 20%, 1986 survey (Andersson- Ellström et al.)** [37] 43%, 1988 survey (Andersson- Ellström et al.)** [37] 100% (Tyden et al.) [38] 55% “low” perceived susceptibility (Woodhall et al.)* [45] 45% (Tyden et al.) [38] 65% (Gottvall et al.) [46] 61% (Höglund et al.) [47] 31% (Tyden et al.) [38]