The COVID-19 pandemic will likely transition to endemic status and no longer become a global problem in two years, according to a new study from Yale.

By conducting an experiment on rats that are just as susceptible to coronaviruses as humans, scientists mapped out the potential trajectory of the COVID-19 pandemic.

In their study published Tuesday in the journal PNAS Nexus, the Yale University researchers indicated that the world could see COVID-19 transition to endemic status within two years.

Endemic is the status of a disease outbreak that is consistently present but limited to a particular region only. This makes it easy for experts to predict and contain its spread.

Malaria is an example of an endemic disease. It is present only in certain countries and regions and is not a global threat, as per Columbia University.

Illnesses like the common cold and the flu are also considered endemic. Though many people get them every now and then, they are not that harmful, especially since seasonal vaccines are available to counter them, according to Medical Xpress.

For the National Science Foundation-funded study, Zeiss and her colleagues observed how humans transmit a coronavirus similar to the one that causes the common cold through rat populations.

They modeled the exposure scenario on the human exposures in the United States, where many people are already vaccinated against COVID-19 while others rely on their natural immunity.

The team also came up with different models for the different types of exposures experienced by people in the U.S., such as close contact and airborne exposure.

“By collecting data on coronaviral reinfection rates among rats, (researchers) were able to model the potential trajectory of COVID-19,” the university was quoted by Hartford Courant as saying.

Yale pointed out other animals such as pigs and chickens also live with endemic coronaviruses. But they can develop a form of protection called “non-sterilizing immunity.”

Yale School of Medicine comparative medicine professor and senior author of the study Caroline Zeiss explained that though this type of immunity is “fairly good,” it quickly wanes.

“And so even if an animal or a person has been vaccinated or infected, they will likely become susceptible again,” she explained.

For Zeiss, their study showed “with natural infection, some individuals will develop better immunity than others.” On the other hand, people who get vaccinated generate predictable immunity.

With both vaccination and natural exposure, people will accumulate a board immunity that would push the virus toward endemic stability, she added.

Nevertheless, the endemic stability of the disease in the U.S. will also depend on what will happen to the virus elsewhere. Since the virus is a global issue, mutations in other places can dictate where the pandemic is heading.

“But I think overall the picture’s hopeful. I think we will be in endemic stability within the next year or two,” Zeiss concluded.

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