By Kate Kelland

LONDON (Reuters) – The world faces “a severe and acute” emergency due to the pandemic caused by the coronavirus and national responses in the coming weeks will be critical to the trajectory of their epidemics, a leading group of scientists said on Thursday.

If no mitigating measures or policies had been taken, the COVID-19 disease outbreak would have resulted in 7.0 billion infections and 40 million deaths globally this year, the scientists said from Imperial College London said.

But if mitigation strategies are implemented that are able to shield the elderly via a 60% reduction in social contacts, and slow but not interrupt transmission of the disease with a 40% reduction in social contacts for the wider population, that disease burden could be cut in half, saving 20 million lives.

“But we predict that even in this scenario, health systems in all countries will be quickly overwhelmed,” said the report, the 12th study by this research team since the new coronavirus first emerged in Wuhan, China in December.

“This effect is likely to be most severe in lower income settings where (health service) capacity is lowest.”

The researchers, led by Neil Ferguson, a professor of mathematical biology, said their analysis suggests healthcare demand worldwide can only be kept within manageable levels with “the rapid adoption of public health measures … similar to those being adopted in many countries” – including testing and isolation of cases and wider social distancing measures.

Ferguson’s 10th study, published earlier this month, was seen as a key influencing factor on moves governments in Britain and Europe took to increase social distancing measures and tighten lockdowns in an effort to slow the expansion of the pandemic.

The study, a mathematical modeling analysis which uses data and estimates to predict potential outcomes, found that in a best case scenario, if countries around the world implement suppression strategies early and sustain them, some 38.7 million lives could be saved.

“Suppression strategies will need to be maintained in some manner until vaccines or effective treatments become available to avoid the risk of later epidemics,” Ferguson’s team wrote in a summary of their study’s findings.

“Delays in implementing strategies to suppress transmission will lead to worse outcomes and fewer lives saved,” they added.

(Reporting by Kate Kelland, editing by Alexandra Hudson)