Vaccine mandates,value pluralism,and policy diversity

Political communities across the world have recently sought to tackle rising rates of vaccine hesitancy and refusal, by implementing coercive immunization programs, or by making existing immunization programs more coercive. Many academics and advocates of public health have applauded these policy developments, and they have invoked ethical reasons for implementing or strengthening vaccine mandates. Others have criticized these policies on ethical grounds, for undermining liberty, and as symptoms of broader government overreach. But such arguments often obscure or abstract away from the diverse values that are relevant to the ethical justifications of particular political communities’ vaccine‐mandate policies. We argue for an expansive conception of the normative issues relevant to deciding whether and how to establish or reform vaccine mandates, and we propose a schema by which to organize our thoughts about the ways in which different kinds of vaccine‐mandate policies implicate various values.     

Vaccine efficacy, and immunity affecting transmission

New candidate malaria vaccines being developed experimentally can only be assessed properly after they have been through the full range of clinical trials and extended follow-up. Defining vaccine efficacy, especially that of multi-component vaccines, is difficult, in particular because the outcome is determined by finely defined epitope specificity. Immune responses can have contrasting effects, some protective, some promoting infection, but concerns that interventions that reduce transmission from a high to a lower intensity will lead to greater risks of severe malaria may not have taken into account all of the many factors that determine the outcome of infection.     

Vaccine trials

This article reviews some of the issues involved in evaluating vaccines in humans. Vaccine trials are required for licensure and are essential for demonstrating a vaccine's safety and protective efficacy. The formal framework of phase I, II, and III trials is described, with particular emphasis on the choice of hypotheses, trial design, and biases that arise in the context of vaccine trials. However, some aspects of a vaccine's performance cannot be evaluated in clinical trials owing to their relatively small size. Thus, vaccine evaluation must continue after licensure, for example, to evaluate the vaccine with respect to rare reactions, duration of protection, and ecological effects. The article reviews some of the methods commonly used for post-licensure studies of vaccine efficacy and safety.     

Protective Vaccine Efficacy when Vaccine Response is Random

Vaccine induced protection against infection is often random because of primary vaccine failures and variation in the immune systems of hosts. We introduce a concept of protective vaccine efficacy in terms of mean relative susceptibility of vaccinated individuals and derive both a lower and an upper bound for it. These bounds apply for all distributions of the vaccine response and can be estimated from data on the size of a major epidemic. Standard errors are given for estimates of the bounds. Bounds are also given for the vaccination coverage required to prevent epidemics and these are also estimable from data on the size of a major epidemic. The results are applied to data on an outbreak of mumps.     

Vaccine renaissance

Vaccines are one of the most useful and cost-effective tools for reducing the morbidity and mortality that are associated with infectious diseases. Here, Jeffrey Almond discusses the selection of articles in this Focus issue, in the context of the challenges and opportunities facing vaccine developers today.