Perceptions of sexual partner safety.

BACKGROUND: Many individuals select sexual partners based on assumed partner STI/HIV safety, yet few studies have investigated how these assumptions are formed. The objective of this research was to determine the extent to which partner safety beliefs were used to evaluate partner safety, and whether these beliefs influenced perceptions of personal STI/HIV risk. METHODS: Participants (n = 317) recruited from an STI clinic completed a structured self-report questionnaire. A Partner Safety Beliefs Scale (PSBS) was developed to determine the factors that most influenced perceived partner safety. Exploratory factor analysis showed that a single factor accounted for 46% of the variance in the PSBS; with an internal consistency of 0.92. Linear regression was used to determine factors predictive of perceived personal STI/HIV risk. RESULTS: Participants endorsed statements indicating that knowing or trusting a sexual partner influences their beliefs about their partner's safety. Linear regression analysis indicated that education, income, number of sexual partners, and PSBS scores were significant predictors of perceived personal STI/HIV risk. CONCLUSIONS: The results of this study indicate that many individuals are relying on partner attributes and relationship characteristics when assessing the STI/HIV status of a sexual partner, and that this reliance is associated with a decreased perception of personal STI/HIV risk. Prevention campaigns need to acknowledge that people are likely to evaluate sexual partners whom they know and trust as safe. Dispelling erroneous beliefs about the ability to select safe partners is needed to promote safer sexual behavior.

Estimating vaccine effectiveness against laboratory-confirmed influenza using a sentinel physician network: results from the 2005-2006 season of dual A and B vaccine mismatch in Canada.

INTRODUCTION: We report a case-control design using a sentinel physician network to estimate vaccine effectiveness (VE) against laboratory-confirmed, medically attended influenza (LC-MAI) and provide results for the 2005-2006 season of dual A and B vaccine mismatch in Canada. METHODS: Participants were patients >or=5 years of age presenting with influenza-like illness (ILI) to a sentinel physician in British Columbia, Canada between November 1, 2005 and April 30, 2006. Cases were participants in whom influenza was identified; controls tested negative for influenza A and B by PCR, R-mix and culture. Isolates were characterized by gene-sequencing and hemagglutination-inhibition (HI) assays. Odds ratios (OR) for LC-MAI in vaccinated versus non-vaccinated persons were derived with adjustment for age and chronic conditions. VE was estimated as [1-OR (vaccinated/unvaccinated)]. RESULTS: The sample included 442 patient visits: median age was 26 years, 10% were >or=65 years, 15% had a chronic condition and 22% received the 2005-2006 trivalent inactivated influenza vaccine >or=2 weeks before ILI onset. Two hundred and six participants were positive for influenza; 107 (52%) had influenza A/H3N2 and 99 (48%) had influenza B/Victoria lineage. Gene sequencing identified mutations away from the vaccine strain at key antigenic binding sites of the hemagglutinin (HA) protein of H3N2 isolates; the neuraminidase (NA) protein was conserved. Based on HI assays, three-quarters of influenza A and all B isolates were mismatched to the 2005-2006 vaccine. Point estimates for VE against LC-MAI were in the range of 50 to 70% for both types of influenza. CONCLUSION: 2005-2006 was the third consecutive season of vaccine mismatch based on varying HA for the A/H3N2 component and the third also for the B component since 2001. Vaccine mismatch resulted in diminished VE but substantial cross-protection. More timely detection of drift variants through gene sequencing of isolates facilitates interpretation of VE results. Since it may be more antigenically conserved, the vaccine content and contribution of NA to overall VE should be further evaluated for both A and B components. Infrastructure for real-time epidemiologic assessment of vaccine performance is important annually and in preparation for a pandemic.