A new report from the World Health Organization (WHO) suggests that new and existing vaccines could have a substantial impact on the emergence and spread of antimicrobial resistance (AMR).
Released today, the WHO report estimates that the introduction and deployment of 44 vaccines against 24 pathogens could avert more than half a million deaths from drug-resistant infections annually, cut AMR-related healthcare costs and productivity losses by billions of dollars, and reduce the number of antibiotics needed to treat infections by 2.5 billion doses annually.Â
Some of the vaccines highlighted in the report, such as the pneumococcal conjugate vaccine, which protects against Streptococcus pneumoniae infections, have been around for years but are underused. Others, including candidates for tuberculosis (TB), Escherichia coli, and Klebsiella pneumoniae, are still in clinical development.Â
AMR is estimated to kill more than 1 million people every year and is associated with nearly 5 million annual deaths. But if these vaccines were widely deployed and included in national and global AMR mitigation strategies, the report concludes, they could drastically reduce the occurrence of infections that drive antibiotic use and create selection pressure for drug-resistant bacteria.Â
“The best infection is the one that doesn’t occur,” said Yvan Hutin, MD, PhD, director of surveillance, protection and control for the WHO’s AMR Division, said in a press briefing. “When we vaccinate people, then they don’t develop infections and they don’t require antibiotics.”
Quantifying the impact of vaccines on AMR
The report’s lead author, WHO technical officer Mateusz Hasso-Agopsowicz, PhD, said the purpose of the report was to quantify the impact that vaccines could have on AMR across three criteria: the AMR-related health burden, the economic burden (including hospital costs and productivity losses), and antimicrobial use. To do so, the WHO analyzed data and sought out expert opinion on 44 distinct vaccines targeting 24 pathogens (19 bacteria, 4 viruses, and 1 parasite).Â
They started by analyzing vaccines already in existence for S pneumoniae, Haemophilus influenzae type b (HIB), and Salmonella Typhi (typhoid). If these vaccines were more widely deployed, they found, they could avert up to 106,000 AMR-related deaths, 9.1 million disability-adjusted life years (DALYs), and $861 million and $5.9 billion in hospital and productivity costs, respectively, while reducing antibiotic use by 142 million defined daily doses (DDDs).Â
“Countries must scale up use of these existing vaccines,” Hasso-Agopsowicz said. “We already have them in our arsenals, and we need to make sure we use them appropriately, especially in countries with low vaccine coverage.”
The report then examined the potential impact of vaccines in the late stages of clinical development, including candidate vaccines for TB, extraintestinal pathogenic E coli (ExPEC), gonorrhea, and Salmonella Paratyphi A. The report estimates that if these vaccines were approved and quickly introduced, they could avert up to 135,000 deaths annually, along with 5 million DALYs, $1.2 billion in hospital costs, and $2.2 billion in productivity losses.Â
The best infection is the one that doesn’t occur….When we vaccinate people, then they don’t develop infections and they don’t require antibiotics.
Hasso-Agopsowicz noted that a TB vaccine alone would dramatically reduce annual antimicrobial use, since TB treatment regimens are very long (6 months or longer) and involve several drugs a day.
“If we were to develop and fully use [TB] vaccines, we could avert between 1.2 and 1.9 billion antimicrobial doses, which is a large proportion of the total antimicrobial burden,” he said.
The final group included vaccines that are in the early stages of clinical development, such as a maternal vaccine targeting K pneumoniae, which is the leading cause of neonatal sepsis globally. Other vaccine candidates in this group target Acinetobacter baumannii, Staphylococcus aureus, and Group A Streptococcus. Together, they could avert up to 408,000 deaths, 23 million DALYs, $30 billion in hospital costs, and $17.7 billion in productivity losses annually. They would also cut antimicrobial use by 548 million DDDs.
The report notes, however, that while the vaccine candidates in this group have a high potential impact on AMR, the feasibility of development for some is low because of challenges in identifying and accessing vaccine target populations.
A call to action
Martin Friede, PhD, of the WHO’s Department of Immunization, Vaccines and Biologicals, said that while health experts have known for many years that vaccines could play a role in controlling AMR, the estimates in the report now give vaccines developers and AMR stakeholders a starting point for prioritizing research and development efforts.
“We haven’t, up until today, been able to say which vaccines could play a role [against AMR], and what the impact really could be,” he said. “Now, with this report, we know how much they can contribute.”
The report recommends that global, regional, and national AMR and immunization strategies and implementation frameworks should include vaccines as interventions to reduce AMR and should advocate for their broader implementation. For example, the report calls for global S pneumoniae vaccine coverage to achieve the WHO and Immunization Agenda 2023 target of 90% in children.Â
To boost vaccine development, the report recommends including AMR endpoints in clinical trials, engaging with regulatory agencies, and creating research roadmaps for challenging bacterial vaccines.
Hasso-Agopsowicz said the report is a “call to action.”
“Governments, the private sector, and investors must invest in the development of new and improved vaccines,” he said. “Strong research and development is really needed and will be a game-changer in fighting the growing threat of antimicrobial resistance.”
