A study in Tanzania found that children who slept under the nets had a survival rate more than 40% higher than their peers who did not.

It had been thought that preventing the disease early in life could leave children with a lack of immunity, simply delaying illness and possible death.

But the study, which followed more than 6,700 children in 1998 and 2019, contradicted this theory.

Dr Salim Abdulla, principal scientist at Ifakara Health Institute (IHI), Tanzania, and study author, said: "We have known for a long time that bed nets save young lives, but we never knew for sure how long the benefits persisted.

"Our study shows that preventing malaria in early childhood has effects that last into adulthood."

Malaria is especially common in sub-Saharan Africa, where it can be deadly for children.

It is caused by a parasite transmitted through mosquito bites, and it killed more than 600,000 people in 2020.

Sleeping under a bed net treated with insecticide is one of the best ways to protect children from the disease.

Dr Gunther Fink, associate professor of epidemiology and household economics at the University of Basel and the Swiss Tropical and Public Health Institute, and first author, said: "It is reassuring to see these long-term benefits, which further highlight the remarkably high returns to investing into early childhood infectious disease prevention and early life health more generally."

Dr Joanna Schellenberg, professor of epidemiology and international health at the London School of Hygiene & Tropical Medicine (LSHTM) and last author on the paper, said: "While our study shows the survival benefit of early-life malaria control persists until adulthood, it also reveals the potential of long-term community-based research."

There were some limitations of the study, acknowledged by the researchers. These included having no information on children who died before the first study visit, meaning survival rates are not representative of all births.

The study is published in the New England Journal of Medicine.