Newcastle Disease (ND) is regarded as one of the major diseases of poultry because of the devastating losses that the virulent form of the ND virus can impose on both commercial and domestic chickens. However, the disease can be controlled through the administration of effective vaccines. Almost all the commercially available ND vaccines require refrigeration and begin to deteriorate rapidly after 1-2 hours if left at room temperature (around 25°C). Subsequently, because maintaining an adequate supply of refrigerated facilities may be a difficult task in many countries with unreliable electrical supplies, the development and large scale production of an effective thermostable ND vaccine seems imperative to support the poultry industry. Such vaccines should be resilient to damage associated with either very cold or hot environments so there are no concerns about the viability of the vaccine in response to temperatures fluctuations that can occur in extreme environments when the difference in temperature during cold and warm seasons can vary greatly. In the following review paper, the development of such a vaccine is discussed, including molecular characterisation, organ tropism of vaccine strains, production, as well as administration methods and their efficacy. It addition, the potential payback has been calculated alongside opportunities provided by removing vaccines from cold chain storage.

We investigated whether straight-line distance from residential compounds to healthcare facilities influenced mortality, the incidence of pneumonia and vaccine efficacy against pneumonia in rural Gambia. Clinical surveillance for pneumonia was conducted on 6938 children living in the catchment areas of the two largest healthcare facilities. Deaths were monitored by three-monthly home visits. Children living >5 km from the two largest healthcare facilities had a 2·78 [95% confidence interval (CI) 1·74–4·43] times higher risk of all-cause mortality compared to children living within 2 km of these facilities. The observed rate of clinical and radiological pneumonia was lower in children living >5 km from these facilities compared to those living within 2 km [rate ratios 0·65 (95% CI 0·57–0·73) and 0·74 (95% CI 0·55–0·98), respectively]. There was no association between distance and estimated pneumococcal vaccine efficacy. Geographical access to healthcare services is an important determinant of survival and pneumonia in children in rural Gambia.

In many applications, we assume that two random observations x andy are generated according to independent Poisson distributions\hbox{$\PPP(\lambdaS)$}𝒫(λS)and \hbox{$\PPP(\muT)$}𝒫(μT)and we are interested in performing statistical inference on the ratioφ = λ / μ of the twoincidence rates. In vaccine efficacy trials, x and y aretypically the numbers of cases in the vaccine and the control groups respectively,φ is called the relative risk and the statistical model is called‘partial immunity model’. In this paper we start by defining a natural semi-conjugatefamily of prior distributions for this model, allowing straightforward computation of theposterior inference. Following theory on reference priors, we define the reference priorfor the partial immunity model when φ is the parameter of interest. Wealso define a family of reference priors with partial information on μwhile remaining uninformative about φ. We notice that these priors belongto the semi-conjugate family. We then demonstrate using numerical examples that Bayesiancredible intervals for φ enjoy attractive frequentist properties whenusing reference priors, a typical property of reference priors.