RIO DE JANEIRO, Brazil (AFP)—Brazil said Monday it was temporarily suspending use of the world’s first single-dose dengue vaccine following two suspicious deaths.

More than half a million people have received doses of the vaccine this year, which was developed publicly in Brazil and approved by health authorities in November.

It is the first single-dose inoculation against the mosquito-borne dengue virus, which can cause high fever, headaches, muscle pain, nausea and rashes, and in rare cases is fatal.