Israeli airstrikes killed at least 15 people including women and children overnight in Gaza, according to hospital officials and a body count by an Associated Press journalist on Sunday.
The latest strikes occurred as Israeli Prime Minister Benjamin Netanyahu prepared to leave Monday for the United States, where he was expected to meet with President Joe Biden and address Congress to make his case for the nine-month war on Gaza while ceasefire negotiations continue.
The already precarious humanitarian conditions inside besieged Gaza have worsened with the discovery of the polio virus as water and sanitation services have suffered for the territory's mostly displaced population of 2.3 million.
Traces of the virus were found in sewage samples in Gaza. The World Health Organization has said no one has been treated for symptoms caused by infection.
Israel's military said solders would be vaccinated, and it would work with organisations to bring in vaccines for Palestinians.
Israel's latest airstrikes were in the Bureij refugee camp in central Gaza, where nine people including two children were killed, and the southern city of Khan Younis, where at least six people were killed including two girls.
Men and women wept and embraced the small bodies in white shrouds.
"Unknown body of five-month baby" was written on one.
Smoke also rose from the Nuseirat refugee camp in central Gaza, but there was no immediate word on casualties.
Israel's war on Gaza has killed at least 38,983 people, according to the Palestinian enclave's health ministry.
A Hamas-led 7 October attack on southern Israel resulted in the deaths of 1,195 people, according to an AFP tally based on Israeli figures.
Some 250 captives were taken and around 120 remain held, about a third of them believed to be dead, according to Israeli authorities.