In 2004, pneumonia killed more than 2 million children worldwide, according to the World Health Organization. By 2015, the number was less than 1 million.
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Better access to antibiotics and improved nutrition account for part of the decline.
But scientists say it's mostly due to vaccines introduced in the early 2000s that target up to 23 of the most deadly forms of the bacterium that causes pneumonia, Streptococcus pneumoniae.
Now, a new vaccine under development could deal another blow to the disease, lowering the number of deaths even further by targeting dozens of additional strains of S. pneumoniae, and anticipating future versions of the bacteria responsible for pneumococcal disease, which includes sepsis and meningitis.
The vaccine provoked an immune response to 72 forms of S. pneumoniae - including the 23 mentioned above - in lab tests on animals, according to new research published in the journal Science Advances.
The study represents the "most comprehensive" coverage of pneumococcal disease to date, researchers say.
"We've made tremendous progress fighting the spread of pneumonia, especially among children. But if we're ever going to rid ourselves of the disease, we need to create smarter and more cost-effective vaccines," says Blaine Pfeifer, PhD, associate professor of chemical and biological engineering at the University at Buffalo's School of Engineering and Applied Sciences, and the study's co-lead author.
Each strain of S. pneumoniae contains unique polysaccharides. Vaccines such as Prevnar 13 and Synflorix connect these sugars - by the sharing of an electron - to a protein called CRM197.
The process, known as a covalent bond, creates a potent vaccine that prompts the body to find and destroy bacteria before they colonize the body.
While effective, creating covalent bonds for each strain of S. pneumoniae is time-consuming and expensive. Plus, this type of immunization, known as a conjugate vaccine, prompts the body to eliminate each of the targeted bacteria types - regardless of whether the bacteria is idle or attacking the body.
Another vaccine, Pneumovax 23, contains sugars of 23 of the most common types of S. pneumoniae. However, the immune response it provokes is not as strong as Prevnar because the sugars are not covalently linked. ■