Study of Brazil favela stricken by Zika shows dengue may protect against virus

Analysis of community where 73% of residents contracted Zika in 2015 offers new clues about epidemic

Scientists studying the 2015 Zika outbreak in Brazil have discovered that people previously exposed to dengue may have been protected from the virus.

Three-quarters of the inhabitants of a favela in the country's north-east caught the mosquito-borne Zika virus during the epidemic. The outbreak left more than 3,000 babies across Brazil with microcephaly, a birth defect caused by mothers catching the virus during pregnancy.