The World Health Organisation has announced it will send more than one million polio vaccines to Gaza after the virus was detected in the Palestinian territory’s wastewater, AFP reports.

WHO chief Tedros Adhanom Ghebreyesus said health workers need free movement within Gaza to administer the vaccines, saying that a ceasefire, or at least a few “days of tranquillity”, was essential to protect Gaza’s children with routine vaccinations.

“WHO is sending more than one million polio vaccines which will be administered in the coming weeks,” he told a press conference. “The detection of polio in wastewater in Gaza is a tell-tale sign that the virus has been circulating in the community, putting unvaccinated children at risk.”

No clinical cases have yet been detected.

Andrea King, from the WHO’s global health cluster team, said the vaccination campaign would be a “huge logistical challenge”.

“It’s vaccines as well as the associated cold chain supplies that are needed to enter Gaza […] as well as the micro-planning within Gaza,” she told the press conference. “The hope is that if everything lines up, these will arrive in time for the planned vaccination dates later this month, the first round to start on August 17.”