GENEVA - Experts at the World Health Organization recommended Tuesday against using blood plasma from people who have recovered from COVID-19 as a treatment for patients with the illness, saying evidence has not shown the costly, time-consuming transfusions to be effective in preventing severe illness or death.RELATED: WHO: Kids in 5-14 age group account for Europe's highest COVID-19 ratesThe guidance against the use of convalescent plasma, a component of blood that is rich in antibodies, was published in the British Medical Journal based on results from 16 trials involving more than 16,000 patients with varying degrees of coronavirus infection, WHO said."Despite its initial promise, current evidence shows that it does not improve survival.