As all four dengue serotypes co-circulate, vaccines need to be tetravalent. Current candidate vaccines include live attenuated
vaccines, chimeric live attenuated vaccines, inactivated or sub-unit vaccines and nucleic acid-based vaccines. Live attenuated
vaccines are in phase 1 testing. Vaccines in advanced preclinical development include DEN-DEN chimaeras, wherein the prM and E protein genes of DEN-1, DEN-3 and DEN-4 have been inserted into the infectious clone of PDK-passaged