Is increasing gonorrhoea resistance in MSM is a result of more treatment, rather than greater sexual activity?

Emerging antibiotic resistance to the last-ditch treatment of Neisseria gonorrhoeae compels health policy-makers to balance opposing concerns.  On the one hand, successfully combating spread of the infection requires targeted treatment of core-group individuals.  On the other, a focus on the core-group causes a rebound in core-group incidence, with maximal dissemination of resistance (Chan & McCabe/STIs (C&M); […]

Read More…

Mathematical models say: switching to HPV nonavalent vaccine brings cost benefits.

STI journal issues of nearly a decade ago, when HPV vaccination was a relatively new thing, hosted a discussion on the issue of which vaccine to choose. The choice at that time, readers will remember, was between GSK’s Cervarix 2vHPV and Merck’s Gardasil 4vHPV (Morris/STIs)*.  Now, the introduction of a third alternative, Gardasil (9vHPV), seems to […]

Read More…

Modeling the potential effectiveness of PrEP as against other preventative interventions in addressing MSM HIV

  Despite the known preventative benefits of ART, the incidence of HIV among UK MSM population has remained relatively constant over the last 10 years and looks set to remain so. The UN 90:90:90 target will soon be achieved for this population, yet the goal of eliminating the infection seems no nearer.  Not surprisingly there […]

Read More…

Increased HIV infectivity in the acute phase of infection may be a less important factor in HIV transmission than we thought

Assessing, as far as we can, the preventative impact of ART on HIV transmission dynamics is evidently very important – both to inform judgments about ART initiation (Wayal & Hart (STI); Cohen (STI)), and also, at the policy level, to be able to evaluate the possible preventative gains of ART scale-up (Shafer & White (STI); […]

Read More…

Achieving HPV herd immunity cost-effectively. When does it make sense to allocate resources preferentially to boys?

Recent empirical studies of HPV vaccination have provided evidence that marginal vaccination costs increase with coverage.  Let us take into account – they argue – not just the vaccine price, but the cost of education and outreach programmes that would be needed so as to reach the yet unvaccinated population.  If we do so, we […]

Read More…

Are African HIV epidemics sustained by exogenous introduction of infection?

What is the relative importance of exogenous and endogenous transmission in sustaining HIV epidemics?  In a study of HIV sub-type distribution in the Middle East, Mumtaz & Abu Raddad (STIs) stress the role of multiple exogenous introductions, as evidenced in the wide diversity of genetic sub-types present in most countries.  At a more local level, […]

Read More…

What can cost-effectiveness modelling tell us about the feasibility of eliminating congenital syphilis in sub-Saharan Africa?

The WHO global initiative for the elimination of congenital syphilis (2007) set the goal of expanding antenatal testing to >90% by 2015.  In sub-Saharan Africa (SSA) recent estimates place the number of mothers infected with active syphilis at 535,000 p.a..  Adverse outcomes – stillbirths, neo-natal morbidity and congenital disease – affect 53%-82% of these pregnancies, […]

Read More…

Modelling ART impact on HIV prevention within discordant couples

The HPTN 052 study, discussed in an earlier blog, appears to offer a godsend:  a demonstrated 96% reduction in HIV transmission in discordant couples using antiretroviral therapy (ART).   Apparently, the extension of ART conveys an additional, and unexpected, benefit in its potential impact on prevention.  But how do we quantify the additional benefit? A recent […]

Read More…