15th Annual Conference on Vaccine Research Opens

If you work on vaccines you know the story of British physician Edward Jenner, whose observation that dairymaids infected with cowpox made them resistant to the far more virulent smallpox virus led him to develop, in 1796, the first experimental vaccine. Jenner’s strategy sounded simple: He inoculated an eight-year-old boy with pus scraped from the cowpox blisters of one of those milkmaids and then inoculated the child six weeks later with matter from a fresh smallpox lesion to prove his hypothesis.

The rest, as they say, is vaccine history.

More than two centuries later, vaccine strategies are anything but simple. Stanley Plotkin, a leading authority on vaccines, who invented the rubella vaccine now used exclusively throughout the world and worked extensively on vaccines for polio, rabies, and cytomegalovirus, offered an historical retrospective of vaccinology that showed how researchers have continued to find new ways of doing what Jenner did from his rural physician’s practice. “The vaccines of the future will be even more complicated,” said Plotkin, during his keynote address that kicked off the 15th Annual Conference on Vaccine Research being held May 7-9 in Baltimore’s Inner Harbor.

Plotkin said the 21st century world of vaccine development is using systems biology approaches to identify the vaccine-induced correlates of protection, and structural biology to better characterize conserved epitopes on the surfaces of viruses. Vaccines will ideally be matched to multiple human leukocyte antigens or contain multiple virulence antigens to improve the immune response.

At the same time, said Plotkin, we have a public increasingly skeptical and resistant to vaccines. He noted, for instance, that measles in France is “rampant and yet we have an effective vaccine.”

Plotkin’s historical perspective set the tone for a day’s talks that focused on some of the major challenges facing vaccine scientists and developers today. A trio of talks on two licensed rotavirus vaccines that are now widely available in industrialized countries and starting to be rolled out in developing countries where the diarrheal disease is a major killer, provided both encouraging and sobering findings.

Umesh Parashar, a team leader for the viral gastroenteritis team at the US Centers for Disease Control and Prevention (CDC), said a post-licensure surveillance conducted in Mexico found the benefits of the new monovalent rotavirus vaccine RV1, or Rotarix, far outweighed the short-term risk of intussusceptions—a bowel obstruction that caused the CDC to suspend use of the RotaShield vaccine in 1999. The absolute number of deaths and hospitalizations averted because of vaccination by Rotarix far exceeded the number of intussusception cases, which was estimated to have occurred in approximately 1 out of every 51,000 to 68,000 vaccinated infants (N. Engl. J. Med. 364, 2283, 2011).

But in an earlier talk, Kathleen Neuzil of PATH, a Seattle-based non-profit formed 30 years ago to improve global health through science and technology that has been providing technical support to countries in Africa and Asia preparing for rotavirus vaccine introduction, said studies have found that the rotavirus vaccines, administered orally, are significantly less effective in children living in the developing world than in the developed world. Poor nutrition and an unhealthy gut environment are both potential reasons as to why children in developing countries have poorer responses to oral vaccines (see A Gut Response to Vaccines,IAVI Report, Nov.-Dec. 2011). Neuzil also said that interference with maternal or breast milk antibodies could also be causing oral vaccine underperformance.