A study in BMJ Global Health in July 2023 uses a static proportional impact model to explore the effect of vaccination on 15 bacterial pathogens. Finding that vaccines are an “effective means” to reduce AMR, the authors call for “increased coverage” of existing products and accelerated development of new vaccines. They believe that their research is the first to estimate “attributable and associated” bacterial AMR burden avertable by vaccination against 15 bacterial pathogens with a combined set of existing and new vaccines by pathogen, infectious syndrome, and region.  

The journey from AM to AMR 

The authors state that since the discovery of penicillin in 1928, antimicrobials have been used against bacteria, fungi, parasites, and viruses, “saving countless lives”. Unfortunately, due to natural or acquired evolution through use of antimicrobial drugs, resistance can occur, rendering the drugs “ineffective” and increasing morbidity and mortality risks.  

“While access to antimicrobial drugs in low-income and middle-income countries to treat infections continues to be a challenge, misuse and overuse of antimicrobials along with lack of access to clean water, sanitation and hygiene, and effective infection prevention and control measures have fuelled the emergence and spread of AMR globally.”  

A review commissioned by the UK government in 2014 suggested that if AMR is not controlled it could cause 10 million deaths annually and trigger a cumulative economic loss of $100 trillion by 2050.  

How does vaccination help? 

When “used in conjunction with other preventative measures”, vaccination has the potential to reduce AMR transmission. For example, it has a “direct influence on the health burden” of AMR by preventing the drug-resistant and drug-sensitive infections and the associated antibiotic use. It can also have an indirect influence, reducing resistant infections in unvaccinated populations through herd immunity.  

Although vaccination has a “significant potential impact” on AMR, evidence is limited because data on the health burden associated with AMR are hard to obtain. The authors attempt to address this evidence gap by analysing the findings of the Global Research on Antimicrobial Resistance project and estimating the vaccine-avertable bacterial AMR burden. The research also informs the first criterion of the WHO-led value attribution framework for vaccines against AMR, which includes 5 criteria: 

  1. Vaccine averted AMR health burden 
  2. Vaccine averted AMR economic burden 
  3. Vaccine averted antibiotic use 
  4. Sense of urgency to develop antimicrobial approaches  
  5. Pathogen impact on equity and social justice  

The GRAM project provided data for age-specific deaths and DALYs associated with and attributable to AMR by pathogen, infectious syndrome, and region for 2019. The estimates of burden were based on statistical predictive modelling of data from systematic reviews, surveillance systems, hospital systems, and other sources.  

15 pathogens were analysed: Acinetobacter baumanniiEnterococcus faeciumEscherichia coli, Group A StreptococcusHaemophilus influenzaeKlebsiella pneumoniaeMycobacterium tuberculosis, Neisseria gonorrhoeae, non-typhoidal SalmonellaPseudomonas aeruginosaSalmonella paratyphiSalmonella typhiShigella spp, Staphylococcus aureus and Streptococcus pneumoniae. These pathogens are part of the WHO evaluation of the value of vaccines in preventing AMR.

The vaccine profiles are set out in a table, exploring vaccine target population, efficacy, coverage, duration of protection, and disease presentation prevented. For currently unavailable vaccines, hypothetical profiles were developed in line with preferred product characteristics (PPCs), target product profiles (TPPs), attributes of advanced candidates, and expert consultations.  

What does the paper suggest? 

The authors find that the AMR burden avertable by vaccination in 2019 was highest for the WHO Africa and South-East Asia regions, for lower respiratory infections, TB, and bloodstream infections by infections, and for M. tuberculosis and S. pneumoniae by pathogen. At the global level, vaccines against the 15 pathogens in the study could avert 0.51 million deaths and 28 million DALYs associated with AMR. We encourage readers to access the study for full results! 

“We highlight the critical need to scale up existing vaccines to high and equitable immunisation coverage, and the acceleration of [typhoid conjugate vaccine] introductions in high burden countries.”  

The researchers call for systematic consideration of the value of vaccines in preventing AMR as vaccines are scaled up and introduced. Furthermore, vaccines “should be explicitly incorporated as tools to combat AMR” into National Action Plans and Immunisation Strategies.  

“For new vaccines in the pipeline and future vaccines, we recommend vaccine avertable burden of AMR to be included in the full value of vaccine assessments.”  

What does this study contribute to our understanding of vaccines in the fight against AMR? Don’t forget to subscribe for more like this!