The most dangerous germs without effective vaccines

The World Health Organization has drawn up a hit list of germs that future vaccines should tackle. In a report published this week, WHO scientists identified 17 common pathogens most in need of new or improved vaccines, including influenza, HIV, norovirus and Staphylococcus aureus bacteria.

Vaccines have long been one of humanity’s most significant public health achievements, helping to control or even eradicate fearsome diseases such as smallpox, polio and most recently Covid-19. But we still don’t have vaccines for many widespread diseases out there, with some current vaccines only modestly effective against their target germ, like the seasonal flu shot. However, there is only a limited amount of time and resources that can be spent on vaccine development. That’s why researchers at the World Health Organization have compiled a list of priority pathogens that need to be addressed above all.

The researchers first consulted with international and local experts to determine criteria for their selection. These include factors such as the annual deaths of children under five from disease or the level of resistance of a pathogen (some of the most worrying bacteria tend to be resistant to antibiotics in primary care). They then compared these criteria with regional data to identify the ten diseases without effective vaccines that most affect a particular part of the world. These regional lists were eventually combined to form a global list of 17 pathogens that deserve the most attention in vaccine development. The researchers’ work, which described the creation of the list, was published Monday in the news eBioMedicine.

“Too often, global decisions on new vaccines are driven solely by return on investment, rather than the number of lives that could be saved in the most vulnerable communities,” said Kate O’Brien, director of the Division of Immunization, Vaccinations and Biology. at the WHO, in a statement of the agency. “This study uses broad regional expertise and data to assess vaccines that would not only significantly reduce diseases that have a major impact on communities today, but also reduce the medical costs faced by families and healthcare systems.”

Five pathogens in particular were identified as priorities for vaccination across all WHO regions: Mycobacterium tuberculosis (the cause of tuberculosis), HIV-1 (the leading cause of HIV in most of the world), Klebsiella pneumoniae, S. aureusand extraintestinal pathogen Escherichia coli. The remaining pathogens were Group A streptococci, hepatitis C virus, cytomegalovirus, Leishmania parasites, non-typhoid Salmonella bacteria, norovirus, Plasmodium falciparum (malaria), causing diarrhea Shigella bacteria, dengue virus, group B streptococci, influenza and respiratory syncytial virus (RSV). The three deadliest diseases on the list, HIV, tuberculosis and malaria, are estimated to kill 2.5 million people worldwide every year.

Existing vaccines are already available for some of these pathogens, such as tuberculosis and influenza, but these provide only partial protection and/or require constant updating in the case of seasonal influenza. Some pathogens have new or improved vaccines that are about to be approved or widely introduced, such as dengue or RSV. Other pathogens have vaccines that show promise in early research but are still a while away from being clear winners, such as Shigella or norovirus, while others need much more research to develop viable candidates, such as hepatitis C, HIV-1, and K. pneumonia.

The WHO’s list is a small part of its larger goal to substantially improve people’s access to vaccination overall by 2030 – an effort known as the Immunization Agenda 2030 (IA2030). And the researchers hope their findings can guide and refine research and development of vaccine programs, both locally and globally.

“As a community, we can and must address these challenges together and quickly to fully realize the benefits and enable sustainable impact of existing and future vaccines,” they wrote in the paper. “By responding to these calls to action, we can move toward the IA2030 vision of ‘A world where everyone, everywhere, at every age, takes the full advantage of immunization to improve health and well-being.’”