COVINGTON: On a 500-acre (200-hectare) plot of land near a small Louisiana town north of New Orleans, about 5,000 monkeys climb and lounge in an enclosure.

Many of the primates, mostly rhesus macaques, at the Tulane National Research Center are destined for use in scientific research, including in experiments for COVID-19.

The facility, with high-level biosafety laboratories able to handle biological threat agents like anthrax, was well-positioned to pivot quickly to COVID-19 research when the coronavirus pandemic hit.

Primates' DNA and physiological features make them ideal models for human comparison when studying diseases, said Skip Bohm, associate director and chief veterinary medical officer at the Tulane center.

"Non-human primates are really critical for us to understand not only the disease and how it affects the organism but also to compare treatments, therapies, vaccinations," Bohm told Reuters.

Rhesus macaques, the primate species most commonly used for scientific research, make up the majority of the center's breeding colony and the 200 adult animals used in its coronavirus experiments over the past year.

COVID-19-related studies by the center include one published in the National Academy of Sciences scientific journal in February that found older individuals with high body mass index and more severe COVID-19 infection exhaled more respiratory droplets, allowing them to become so-called 'super-spreaders.'

Primates were the crux of the study, said Chad Roy, study co-author and the center's director of infectious disease aerobiology.

Among future work, the center plans to study "long COVID," the incidence of one in 10 diagnosed patients remaining unwell long after their acute infection.

"There are many different therapeutics that are coming online that need to be tested, and with the network that we have, we can compare one treatment to another," said center director Jay Rappaport, referring to the facility's role coordinating the COVID-19 work of the seven U.S. primate research centers.

Once experiments are concluded, the Tulane center euthanizes the monkeys for tissue collection, allowing researchers to study COVID-19's impact beyond the respiratory system.

Kathy Guillermo, of laboratory investigations at the People for the Ethical Treatment of Animals (PETA), said primates should not be used for testing.

"They wouldn't have to kill them if they didn't use them," she said. "What we're going to learn of value is going to be what we learn from human beings."