Health workers in Gaza are set to administer a second polio vaccine dose to 590,000 children starting Monday. The first round vaccinated 95% of eligible children and was successful. The World Health Organization emphasizes the importance of this second dose to curb virus spread. Success depends on humanitarian pauses in fighting, with assurances from the Israeli military. The campaign will occur in three phases, also providing vitamin A. The WHO initially aimed to vaccinate 640,000 children but revised estimates due to displacement and casualties from ongoing conflict.