The latest COVID-19 vaccine is set for release in September. But health experts say it remains unclear how many Americans will choose to get the new shot.

The efforts to prepare a new vaccine come as hospitals in the United States report increases in COVID-19 patients since early July. But the number of hospitalizations is still far below those reported earlier this year and throughout the COVID-19 pandemic.

A drop in infections has caused demand for the vaccine to fall sharply since the first shot became available in 2021. Officials say that overall, more than 240 million people in the U.S. had received at least one COVID-19 injection. That number represents about 73 percent of America's population.

FILE - A vial labelled VACCINE Coronavirus COVID-19 is seen in front of a stock graph in this illustration taken on January 17, 2022. (REUTERS/Dado Ruvic/Illustration)

FILE - A vial labelled "VACCINE Coronavirus COVID-19" is seen in front of a stock graph in this illustration taken on January 17, 2022. (REUTERS/Dado Ruvic/Illustration)

By autumn of 2022, fewer than 50 million people got the vaccine shots. By that time, most people in the U.S. had either been infected with COVID-19 or had received at least one shot.

Public health experts have advised people to look at COVID-19 vaccines the same as they do shots for other sicknesses, such as the flu. Flu vaccines are developed to fight the latest virus versions, called variants, and are generally administered once per flu season.

But efforts to get people to seek COVID-19 shots are likely to be hurt by decreasing concern about the virus. Some people also question if the vaccines are safe.

Healthcare providers and drug businesses have said they plan to start offering the new COVID-19 vaccine next month. The vaccine was developed to fight virus versions linked to the Omicron variant, which has been spreading in the U.S. since last year.

Ashley Kirzinger is a lead researcher with the Kaiser Family Foundation. She told Reuters news agency that health officials need to send a clear message to the public that COVID-19 has not gone away. In addition, the messaging should note the new vaccine can protect individuals from serious sickness and hospitalization.

Kirzinger noted her foundation has carried out public opinion studies on the issue. She said the top reason vaccinated people gave for rejecting more vaccinations was the belief that people were protected from the virus because of earlier shots or infections.

The two largest COVID-19 vaccine makers – Pfizer-BioNTech and Moderna – have predicted far less demand this autumn for the shots. Last year, vaccine sales by Pfizer and Moderna reached a combined $56 billion worldwide. This year, experts estimate the shots will bring in $20 billion for the companies.

The COVID-19 public health emergency officially ended in May. Since then, the government has handed over much of the vaccination