
A fifth child is in critical condition after contracting the respiratory illness, Vladislav Vukomanovic, the deputy head of a Belgrade paediatric hospital, told broadcaster RTS.
The doctor said around 70 children have been diagnosed, with two-thirds requiring hospitalisation.
Vukomanovic blamed a lack of vaccination, including among older adults, for the current spread.
Vaccination against whooping cough is mandatory in Serbia. However, a rising number of parents are refusing to vaccinate their children, leading to periodic outbreaks across the region.
Neighbouring Croatia has also struggled to contain a whooping cough epidemic that health officials said resulted in a drop in inoculation rates linked to the anti-vaccine movement.