The general consensus from epidemiological game-theory studies is that vaccination coverage driven by self-interest (Nash vaccination) is generally lower than group-optimal coverage (utilitarian vaccination). However, diseases that become more severe with age, such as chickenpox, pose an exception to this general consensus. An individual choice to be vaccinated against chickenpox has the potent...

Antigenically evolving pathogens such as influenza viruses are difficult to control owing to their ability to evade host immunity by producing immune escape variants. Experimental studies have repeatedly demonstrated that viral immune escape variants emerge more often from immunized hosts than from naive hosts. This empirical relationship between host immune status and within-host immune escape...

Punctuated antigenic change is believed to be a key element in the evolution of influenza A; clusters of antigenically similar strains predominate worldwide for several years until an antigenically distant mutant emerges and instigates a selective sweep. It is thought that a region of East-Southeast Asia with year-round transmission acts as a source of antigenic diversity for influenza A and se...

Many organisms vary their level of investment in defensive characters. Protective traits may be induced upon exposure to predators or parasites. In a similar way, humans vaccinate in response to threatening epidemics. When most group members defend themselves, epidemics die out quickly because parasites cannot spread. A high level of group (herd) immunity is therefore beneficial to the group. T...

This paper describes a computer model that mimics the spread of bovine viral diarrhoea virus (BVDV) infection through a closed herd. The model is able to simulate the spread of infection when a persistently infected (PI) animal is introduced into an infection-free herd, and it is used to investigate the role of persistently infected animals, seroconverting animals, loss of PI calves and duratio...

Vaccination policy in the case of human papillomavirus (HPV) has remained a constant source of controversy ever since Gardasil, Merck's vaccine against HPV, received US Food and Drug Administration approval in the summer of 2006. This controversy has centered on the risks and benefits of vaccinating girls and women in rich and poor nations alike. However, despite all of the attention created by...

BACKGROUND Socioeconomic inequalities in vaccination can reduce the ability and efficiency of global efforts to reduce the burden of disease. Vaccination is particularly critical because the poorest children are often at the greatest risk of contracting preventable infectious diseases, and unvaccinated children may be clustered geographically, jeopardizing herd immunity. Without herd immunity, ...

INTRODUCTION For pathogens such as influenza that cause many subclinical cases, serologic data can be used to estimate attack rates and the severity of an epidemic in near real time. Current methods for analysing serologic data tend to rely on use of a simple threshold or comparison of titres between pre- and post-epidemic, which may not accurately reflect actual infection rates. METHODS We p...

We consider the interplay of vaccination and migration rates on disease persistence in epidemiological systems. We show that short-term and long-term migration can inhibit disease persistence. As a result, we show how migration changes how vaccination rates should be chosen to maintain herd immunity. In a system of coupled SIR models, we analyze how disease eradication depends explicitly on vac...