It was not until after watching her home in Aguada, P.R., fill with water and the roofs blow off houses during Hurricane Maria that Suzette Sanchez began noticing those around her dying.

There was the family friend whose heart surgery had to be postponed when the hospital closed. There was the volunteer who contracted leptospirosis, a bacterial infection often caused by contact with rat urine, while cleaning.

“When the government said only 64 people died, I knew it wasn’t true because I had many friends that lost a loved one after the storm,” Ms. Sanchez said.

Days after a new study from researchers at the Harvard T.H. Chan School of Public Health estimated that the death toll from Hurricane Maria may be as high as 4,645 people, mainly because of delayed medical care, hundreds of protesters gathered on Saturday in the shadow of the United Nations to demand that the international organization audit the number of casualties.