JAMA and Slate on vaccine-related replacement disease

A common question asked about vaccines that target specific variants of a pathogen (such as HPV, pneumococcus, or meningococcus) is how great the likelihood is that 'replacement disease' may occur. Simply stated, this phenomenon describes the emergence of new serotypes or subtypes not included in a vaccine becoming more prevalent as those that are included in the vaccine are eliminated.

A paper in JAMA this spring suggested replacement disease may be occurring among recipients of Prevnar, Wyeth's pneumococcal conjugate vaccine. (Four doses of the vaccine are recommended for all U.S. infants.) The paper was the basis for a commentary by Arthur Allen ("Fear of Replacement: What if a vaccine kills off one strain of a disease—but makes room for another?") that appeared in Slate late last month.

Ben Kleifgen, working at the Penn Center for Bioethics this summer, summarizes both items:

"In the JAMA paper, CDC’s Arctic Investigations Program observed an increase in pneumococcal infections in Native Alaskans receiving Prevnar. Of particular concern to researchers is the fact that the infections are largely from serotype 19A, a highly virulent but previously quite rare strain. Allen wonders if the threat of replacement disease may discourage further vaccine development, although the situation may not be that bleak. There is evidence that the new strain may be on the rise worldwide, unrelated to the use of Prevnar. In addition, Wyeth and GSK are both working on new pneumococcal vaccines that will cover 19A."

$200m in GAVI funding for rotavirus and pneumococcal vaccines

Our hometown newspaper, The Philadelphia Inquirer, reports today on the $200 million pledge made late last week by GAVI to support vaccination against rotavirus and pneumococcus in the developing world. Here's the GAVI press release about the announcement.

The Inquirer story quotes GAVI's estimates of the potential worldwide benefit of each vaccine in the coming years: 370,000 deaths and 14 million hospitalizations due to rotavirus could be prevented by 2015, as could 447,000 deaths attributable to pneumococcus.

The Inquirer story explains:

"GAVI said it would coordinate with the World Health Organization and UNICEF to acquire and distribute vaccines first in 'countries where the vaccines have shown efficacy. As new and more effective vaccines come on the market, and as political support grows for introducing them in other GAVI countries, we will scale up to meet demand.'"

$75 Million from Gates to PATH for pneumonia vaccine

The Seattle Post-Intelligencer reports this morning...

"Pneumonia is the leading killer of children worldwide, taking a life every 30 seconds, so the Bill & Melinda Gates Foundation has awarded Seattle-based PATH $75 million to create inexpensive vaccines tailored specifically to the disease strains prevalent in poor countries."

The award will be announced today at the 5th International Symposium on Pneumococci and Pneumococcal Diseases in Australia. PATH, a non-profit that frequently receives support from Gates, describes its mission as "improv[ing] the health of people around the world by advancing technologies, strengthening systems, and encouraging healthy behaviors."

The Seattle P-I continues...

"Children in the United States and Europe are routinely vaccinated against the leading strain of the bacteria, Streptococcus pneumoniae. But the Western vaccine does not protect well against varying strains found in developing countries -- where 90 percent of pneumococcal deaths occur.

Also, the current vaccine costs from $40 to $60 a dose -- a price that is completely unaffordable for most people in poor countries living on perhaps a dollar a day or less."

The vaccine referred to is Wyeth's Prevnar. Much like HPV, there are dozens of strains of pneumococcus, and Prevnar only provides protection against the 7 most common in the U.S. and elsewhere in the developed world. The stated goal of this project is to bring down dramatically the cost of a pneumonia vaccine (the story suggests $5/dose as a target) while developing candidate vaccines that are not specific to individual strains of the bacteria.

This news is only the most recent example of the leading role played by the Gates Foundation in steering vaccine research in new directions. Last week, we wrote about their commitment to a new tuberculosis vaccine for the developing world, and a few weeks earlier, we noted a Financial Times profile on Bill and Melinda Gates and their philanthropic efforts.