Vaccines save lives, not only by directly preventing life-threatening diseases, but also by curbing the potentially fatal phenomenon of antimicrobial resistance. by how much? At least half a million deaths could be saved every year thanks to vaccines. To estimate it is one studio conduit by WHO, the International Vaccine Institute, Korea and the London School of Hygiene & Tropical Medicine, just published on the pages of the BMJ Global Heatlh.
How vaccines help fight antimicrobial resistance
Antimicrobial resistance is a huge problem: it is estimated that nearly 5 million deaths are associated with antibiotic resistance every year. Deaths that vaccines, even those that already exist, could help stem, in many ways. Vaccines in fact, write the authors at the beginning of their article, can directly prevent infections and their transmission, including those of strains with antimicrobial resistance, even indirectly, through herd immunity. They can thus discourage the use of antimicrobials – the more they are used, the greater the risk of resistant strains emerging – especially if they are used inappropriately (for example against the flu) or to treat secondary infections caused by viral diseases. That’s in theory, but in fact, how effective are vaccines at fighting antimicrobial resistance? Something, for some infection is known, but still too little.
Why are vaccines said to help fight antibiotic resistance? 09 June 2023
The WHO study
This is why the researchers’ work sought to estimate how much the use of 15 vaccines (existing or under development) against bacterial infections could help reduce the phenomenon of antimicrobial resistance. The considered bacteria were Acinetobacter baumannii, Enterococcus faecium, Escherichia coli, Streptococcus di gruppo A, Haemophilus influenzae, Klebsiella pneumoniae, Mycobacterium tuberculosis, Neisseria gonorrhoeae, Salmonella non typhoid, Pseudomonas aeruginosa, Salmonella paratyphi, Salmonella typhi, Shigella, Staphylococcus aureus from Streptococcus pneumoniae. For bacteria still without a vaccine, the researchers based themselves on the data currently available and on the evaluations of some experts. The reference year was 2019 and the estimates were made considering its various scenarios, one that only took into account primary vaccination schemes for specific age groups – or on the basis of the indications of existing vaccines and of the populations included in the trials – another instead that considered a larger audience of subjects at risk, such as the elderly. In this case, the authors point out, we are referring to an ideal model in which vaccines would be distributed to all those who could benefit from them.
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The benefits of vaccines against antimicrobial resistance
The results show that using vaccines would have important gains in reducing the burden of antimicrobial resistance. In the first scenario – with vaccines reserved for target populations – more than half a million deaths and 28 million years of life lost (DALYs, disability-adjusted life-years, DALYs) could be saved due to infections. These benefits, of course, would be amplified by considering a larger population to be vaccinated: in this case, in fact, another 1.2 million deaths could be avoided and another 37 DALYs saved. The numbers refer to deaths and years of life lost associated with antimicrobial resistance, considering those directly attributable to antimicrobial resistance would increase a little more. And we are talking about conservative estimates, because in their calculations the researchers did not consider the transmission of resistant strains, nor vaccines against viruses, they specify.
Africa and the regions of South-East Asia are the areas – unsurprisingly – where vaccines would be particularly valuable especially for combating lower respiratory tract infections, tuberculosis and blood infections. While looking at bacteria, vaccines would mostly help fight infections and complications of the Mycobacterium tuberculosis and of Streptococcus Pneumoniae.
The study is only an estimate, not without limits, as the authors themselves admit – such as the fact that coverage could be different from area to area, and therefore have different impacts – but the message is clear: vaccines must be considered as tools to combat antimicrobial resistance, and evaluated as such as well.