Although cholera vaccine was not used in the first two

Although cholera vaccine was not used in the first two main waves of the epidemic, pilot projects were done in 2012 to deliver Shanchol to about 100 000 people in urban and rural Haiti. Subsequently, the Ministry of Health undertook larger campaigns in 2013, and plan to implement additional OCV campaigns in the coming years. Furthermore, the Ministry of Health has included the use of OCV in its national strategy for elimination of cholera, along with a continuing effort to improve water and sanitation. The earlier reports showed that OCV was acceptable and that OCV campaigns were feasible in Haiti, but a new report by Louise Ivers and colleagues in provides important new information, showing that the vaccine\'s effectiveness in Haiti is comparable to that found in endemic countries of Asia and Africa. Of 47 people with cholera, 33 (70%) self-reported CA-074 versus 167 (89%) of 188 controls (vaccine effectiveness 63%, 95% CI 8–85). Conversely, there was no association between self-reported or verified vaccination and non-cholera diarrhoea (vaccine effectiveness 18%, 95% CI −208 to 78 by self-report and −21%, −238 to 57 by verified vaccination). Similar efficacy and effectiveness of the two killed OCVs—Dukoral and Shanchol—has been documented. The two vaccines differ in that Dukoral is more expensive and is administered in a glass of buffer solution to preserve the B subunit component of the vaccine, which increases the logistic requirements for its use. By contrast, Shanchol, which has no B subunit, needs no buffer, is less costly, and consists of only 1·5 mL liquid, which can be consumed directly from a vial. Shanchol is now available through the OCV stockpile, which is supported partly by the Global Alliance for Vaccines and Immunization. It is being used primarily as a response to an outbreak, but it will probably also be used for groups at risk in endemic areas. Clearly, much work is needed to identify how best to use the vaccine in a manner that maximises its cost-effectiveness. Some of the limitations of this study are related to the small sample size, which is a common problem in cholera effectiveness studies and which limits the ability to discern differences among subgroups. In this study, the point estimates differed in some subgroup comparisons (eg, age group and time since vaccine administration), but the sample was not powered to identify whether these differences were real. Ivers and colleagues were also not able to assess the potential for herd protection, which was found in other studies. Although OCV protects vaccinated individuals, it also lowers the risk for unvaccinated neighbours if vaccine coverage is sufficiently high. Modelling work predicted that 50% coverage could avoid transmission in endemic areas. Thus, further studies are needed to better understand how to maximise the effect of herd protection.
Estimates of life expectancy are of obvious importance to people with HIV-1, and are essential to monitor and predict the progress of the HIV/AIDS epidemic and to plan health services. The Rwandan study reported by Sabin Nsanzimana and colleagues in is the first from sub-Saharan Africa to focus on the evolution of HIV-positive life expectancy during the scale-up of antiretroviral therapy, and is a welcome addition to a small body of data. The investigators show that the scale-up of antiretroviral therapy resulted in substantial gains in life expectancy, with near-normal life expectancy in individuals enrolled in care with little immunodeficiency. How reliable are estimates of life expectancy in people living with HIV? Life expectancy is the number of years that a person of a particular age would live, assuming that current age-specific mortality rates remain constant. Calculations might thus seem straightforward, but for people living with HIV in sub-Saharan Africa they are not. First, analyses rely on data for patients in treatment and care programmes, which might not be representative of all individuals living with HIV-1. Second, loss to follow-up of patients after the start of antiretroviral therapy is common. In the absence of functioning systems for vital statistics or outreach programmes to trace patients who were lost, mortality for these individuals remains unknown. To ignore the deaths in patients lost to follow-up substantially biases mortality downwards: death accounts for a substantial proportion of patients lost to follow-up. Last, the duration of follow-up needs to be standardised across calendar periods. The risk of death is not uniform after initiation of antiretroviral therapy, but falls with increasing duration of therapy. Nsanzimana and colleagues addressed all of these issues. The researchers limited the duration of follow-up to 3 years in all calendar periods, by contrast with other studies (eg, an analysis from the UK and a collaborative study in high-income countries). The Rwandan study therefore controlled at least to some extent for survivor bias, although how similar lengths of follow-up were in the two calendar periods is unclear. Many patients from a nationally representative sample of clinics were included, which is an important strength of the study. Unfortunately, no information about mortality in patients lost to follow-up was obtained, but statistical adjustment was made assuming that about half of patients lost to follow-up had died. In Rwanda and many other countries in sub-Saharan Africa, vital statistics function poorly, with only a small number of deaths registered. The exception is South Africa, where coverage of vital registration is near universal and data from treatment and care programmes for HIV can be linked with mortality records to obtain accurate mortality estimates. The importance of the deaths among patients lost to follow-up in the Rwandan study is underlined by the much-higher estimates of life expectancy obtained when no adjustment was made, and uncertainty remains in this regard.