Babies of HIV-infected mothers should be given an inexpensive antibiotic to prevent infections and prolong their lives, United Nations aid agencies said on Tuesday.

The recommendation by the U.N. Children’s Fund (UNICEF), UNAIDS and World Health Organization (WHO) follows a report in The Lancet medical journal last Friday that a daily dose of the drug co-trimoxazole nearly halved the death rate in children.

Trials involving children aged one to 14 years in Zambia lasted 19 months, and the drug was deemed a success.

The U.N. agencies, in their joint advice to health ministries and aid workers, said that co-trimoxazole was a “crucial potentially life-saving intervention that should be given to all HIV-exposed children born to HIV-infected mothers.”

It should be offered as “part of a basic package of care to reduce morbidity and mortality,” the agencies said.

Treatment should begin in children from four to six weeks of age and should continue until HIV infection has been definitively ruled out and the mother is no longer breast-feeding, they added.

It should be used before children require antiretroviral drugs “because it may even postpone the time at which antiretroviral therapy needs to be started,” the joint statement said.

Jim Kim, director of WHO’s HIV department, told Reuters: “This is an important piece of information which we hope to get out so that ministries of health change practices very quickly. We’d be happy if it is implemented in the next six months.”

The drug is already used to both prevent and treat a form of pneumonia that commonly kills both HIV-infected adults and children, according to WHO.