How effective are emergency vaccines during outbreaks?

The Star

2 days ago

Doctors Without Borders (also known by its French acronym MSF) staff disinfecting body bags containing deceased Ebola patients with chlorine before they are incinerated in a crematorium during the 2014 outbreak in West Africa. This was before the Ebola vaccine was available. — MSF filepic
Emergency vaccination during outbreaks of diseases like cholera, Ebola and measles have over the past quarter-century reduced deaths from such illnesses by nearly 60%, according to a new study.
A similar number of infections are also believed to have been prevented, while billions of euros have been generated in estimated economic benefit.
The Gavi vaccine alliance, which backed the study, said it collaborated with researchers at Burnet Institute in Australia to provide the world's first look at the historical impact of emergency immunisation efforts on public health and global health security.
'For the first time, we are able to comprehensively quantify the benefit, in human and economic terms, of deploying vaccines against outbreaks of some of the deadliest infectious diseases,' Gavi chief Sania Nishtar said in a statement.
'This study demonstrates clearly the power of vaccines as a cost-effective countermeasure to the increasing risk the world faces from outbreaks.'
The study, published on July 12 (2025) in the British Medical Journal ( BMJ ) Global Health , examined 210 outbreaks of five infectious diseases – cholera, Ebola, measles, meningitis and yellow fever – in 49 lower-income countries between 2000 and 2023.
Vaccine roll-outs in these settings had a dramatic impact, with the study showing they reduced both the number of infections and deaths by almost 60% across the five diseases.
For some of the diseases, the effect was far more dramatic.
Vaccination was shown to decrease deaths during yellow fever outbreaks by a full 99%, and 76% for Ebola.
At the same time, emergency vaccination significantly reduced the threat of outbreaks expanding.
It also estimated that the immunisation efforts carried out during the 210 outbreaks generated nearly US$32bil (RM136bil) in economic benefits just from averting deaths and years of life lost to disability.
That amount was however likely to be a significant underestimate of overall savings, it said, pointing out that it did not take into account outbreak response costs or the social and macro-economic impacts of disruptions created by large outbreaks.
The massive Ebola outbreak that hit West Africa in 2014 before the existence of approved vaccines, for instance, saw cases pop up worldwide and is estimated to have cost the West African countries alone more than US$53bil (RM225bil).
The study comes after the World Health Organization (WHO) warned in April (2025) that outbreaks of vaccine-preventable diseases such as measles, meningitis and yellow fever are on the rise globally amid misinformation and cuts to international aid.
Gavi, which helps vaccinate more than half the world's children against infectious diseases, is itself currently trying to secure a fresh round of funding in the face of the global aid cuts and after the US government announced last month that it would stop backing the group. – AFP