Expert review of vaccines
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Herpes zoster (HZ; shingles) results from reactivation of varicella-zoster virus that has been dormant in the spinal and cranial sensory ganglia following primary infection with varicella (chickenpox), usually during childhood. In developed countries more than 95% of the adult population are seropositive for varicella-zoster virus and are therefore at risk of developing HZ. Reactivation can occur at any age, but it is associated with an age-related decline in cell-mediated immunity and therefore occurs more frequently in older adults. ⋯ Management is challenging and often unsatisfactory (<50% of patients gain 50% relief of pain). With the older adult population steadily growing in size, the number of patients presenting with HZ is also likely to increase and this will place a greater burden on healthcare systems. Prevention strategies, such as vaccinating those at greatest risk, may offer the best option for the future.
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Enterovirus 71 (EV71) was first isolated in 1969 in California, USA. Several epidemic outbreaks with high mortality rates have occurred in European and Asian Countries (Bulgaria in 1975, Hungary in 1978, Malaysia in 1997, Taiwan in 1998 and China in 2008). ⋯ Recently, several EV71 vaccine candidates, including live-attenuated virus, inactivated whole virus, recombinant viral protein, virus-like particle and DNA vaccines, have been evaluated in animals but no clinical trial has yet been conducted. Based on historical experiences with poliovirus vaccines and animal studies, the inactivated whole-virus vaccines are feasible and could be licensed readily, so these are targeted for preparing clinical trials in several organizations in Asia.
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Cervarix and Gardasil are two prophylactic HPV vaccines designed primarily for cervical cancer prevention. Cervarix is effective against HPV-16, -18, -31, -33 and -45, the five most common cancer-causing types, including most causes of adenocarcinoma for which we cannot screen adequately. ⋯ The most important determinant of vaccine impact to reduce cervical cancer is its duration of efficacy. To date, Cervarix's efficacy is proven for 6.4 years and Gardasil's for 5 years.
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Worldwide, rotaviruses are the single most important agents of severe gastroenteritis in infants and young children. Globally, it is estimated that every year rotavirus gastroenteritis causes more than 125 million episodes of diarrhea and nearly 527,000 deaths, mainly in developing countries. The development of new effective and safe rotavirus vaccines was recognized as the most effective intervention strategy that could yield a significant impact on the burden of rotavirus disease. ⋯ In a recently completed vaccine trial in South Africa and Malawi, Rotarix showed an overall efficacy of 61.2% (95% CI: 44.0-73.2) by 1 year of age. Although these rates are lower than those from developed and middle-income countries, they look promising given the lack of other effective interventions. With the expanding introduction of rotavirus vaccines into national immunization programs, postmarketing surveillance should be conducted to measure the impact of rotavirus vaccination, as well as continued monitoring of circulating rotavirus strains.