Pneumococcal vaccine strikes only when needed

Pneumococcal vaccine strikes only when needed

To treat and prevent illnesses caused by pneumococcus,  doctors almost exclusively relied on penicillin and other common antibiotics. While still used, the effectiveness of these drugs has been waning for decades due to bacteria developing antibiotic resistance.

The situation led pharmaceutical companies to develop preventive vaccines, which have reduced deaths and illnesses, especially in developed nations. But pneumococcus remains a serious problem.

Pneumonia killed 1.3 million people worldwide in 2011, with the majority of deaths in Sub-Saharan Africa and South Asia. In the United States alone, pneumonia, meningitis and sepsis cause tens of thousands of deaths each year, according to the National Foundation for Infectious Diseases.

One reason for this is that current vaccines target only a small percentage - those known to cause the most severe infections - of the more than 90 strains of pneumococcus. These vaccines, which identify pneumococcus by a sugar coating that surround the bacteria, are 56 to 88 percent effective.

A new vaccine allows pneumonia-causing bacteria to colonize inside the body, springing into action only if the bacteria pose a threat.

The breakthrough approach, coupled with the protein-based vaccine's potential to counteract more than 90 strains of the bacteria, has the makings to override how vaccines have worked (destroying bacteria before colonization) since the days of Louis Pasteur.

Moreover, it offers what could be the most direct and broad response to pneumonia - the leading cause of death of children worldwide under the age of 5, according to the World Health Organization - as well as meningitis, sepsis and other serious infections caused by Streptococcus pneumoniae, a bacteria more commonly known as pneumococcus.

"These are very serious illnesses that we haven't been able to completely suppress. The vaccine we're developing could finally get that job done," says senior author of the Proceedings of the National Academy of Sciences study.

The team took a different approach. Its vaccine identifies strains by proteins attached to the surface of pneumococcus. Laboratory tests show the vaccine can defend against more than 12 strains and that it's 100 percent effective at promoting the appropriate immune response.

Computer simulations indicate the vaccine would be effective against all strains but additional tests are needed to confirm that.

The ability to fight numerous strains is important because developing new versions of existing vaccines is both costly and time-consuming.
The new vaccine also differs from what's on the market by its response to the bacteria.

Current vaccines teach the immune system to indiscriminately destroy bacteria and other pathogens, thus preventing colonization. The approach works, but there is growing concern that it can create space within the body for new and potentially more harmful alternatives to establish residence - similar to antibiotic resistance resulting in new and more potent pathogens.