Israel-Hamas Live News: Netanyahu to Meet With U.S. Official to Discuss Hostage Deal

These fatalities would be in addition to the more than 29,000 deaths in Gaza that local authorities have attributed to the conflict since it began in October. The estimate represents “excess deaths,” above what would have been expected had there been no war.

In a second scenario, assuming no change in the current level of fighting or humanitarian access, there could be an additional 58,260 deaths in the enclave over the next six months, according to the researchers, from Johns Hopkins University and the London School of Hygiene and Tropical Medicine.

That figure could climb to 66,720 if there were outbreaks of infectious disease such as cholera, their analysis found.

Even in the best of the three possibilities that the research team described — an immediate and sustained cease-fire with no outbreak of infectious disease — another 6,500 Gazans could die over the next six months as a direct result of the war, the analysis found.

The population of the Gaza Strip before the war was 2.2 million.

“This is not a political message or advocacy,” said Dr. Francesco Checchi, professor of epidemiology and international health at the London School of Hygiene and Tropical Medicine.

“We simply wanted to put it at the front of people’s minds and on the desks of decision makers,” he added, “so that it can be said afterward that when these decisions were taken, there was some available evidence on how this would play out in terms of lives.”

Dr. Checchi and his colleagues estimated the projected excess deaths from health data that was available for Gaza before the war began and from that collected through more than four months of fighting.

Their study considers deaths from traumatic injuries, infectious diseases, maternal and neonatal causes, and noncommunicable diseases for which people can no longer receive medication or treatment, such as dialysis.

Dr. Checchi said the analysis made it possible to quantify the potential impact of a cease-fire in lives. “The decisions that are going to be taken over the next few days and weeks matter hugely in terms of the evolution of the death toll in Gaza,” he said.

The projected 6,500 deaths even with a cease-fire is predicated on the assumption there will not be epidemics of infectious disease. With an outbreak of cholera, measles, polio or meningitis, that figure would be 11,580, said Dr. Paul Spiegel, director of the Hopkins Center for the Humanitarian Health and an author of the research, which has not been peer-reviewed.

While it is obvious that a military escalation would bring additional casualties, he added, policymakers should be cognizant of the range in the number of deaths that these scenarios indicate.

“We hope to bring some reality to it,” Dr. Spiegel said. “This is 85,000 additional deaths in a population where 1.2 percent of that population has already been killed.”

Patrick Ball, an expert on quantitative analysis of deaths in conflict who was not involved in the research, said it was unusual to see such a rigorous effort to calculate the potential humanitarian cost of an ongoing war.

“The paper illuminates this conflict in a way that we haven’t had in any prior conflicts,” said Dr. Ball, who is the director of research for the Human Rights Data Analysis Group, a nonprofit organization. “It illuminates the probable costs in human lives and human suffering of different kinds of future actions that are under human control.”

“People are going to make decisions that are going to lead to one of these three scenarios, or some complex mix of them, and this gives us a sense of what the likely outcomes of those decisions are,” he added.

The analysis projects that fatalities from traumatic injuries in Gaza over the next six months will be distributed across all ages and genders.

“Forty-three percent of the trauma deaths occur among females, and 42 percent are among children under 19 years,” the paper says, which “reflects the intensity and widespread nature of bombardment.”

Even with an immediate cease-fire, war-related deaths would continue, according to the analysis. The toll includes deaths of people who succumb to previous injuries or who are hurt by unexploded ordnance, deaths of babies and women for whom complex care in childbirth is not possible, and deaths of undernourished children who are unable to fight off infections such as pneumonia.

“I don’t think people realize how long it will take for that to change,” Dr. Spiegel said.