December 8, 2023

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Yale University predicts that COVID-19 may turn into an endemic disease in two years

Yale University predicts that COVID-19 may turn into an endemic disease in two years


Yale University predicts that COVID-19 may turn into an endemic disease in two years.


In November 1889, a respiratory virus caused the last global pandemic of the 19th century and set off at least three waves of infection over a period of 4-5 years.

The global population at the time was only 1.5 billion, and the pandemic claimed some 1 million lives.

Scientists believe the culprit in the pandemic is the OC43 coronavirus , which originated in cattle and has now evolved to cause only the common cold in humans.


The common cold and influenza are very common diseases. Across the globe, everyone gets infected once in a while.

For most people, this endemic epidemic is no longer a physical threat, and some people even recover without medication.


However, the helpless new coronavirus (SARS-CoV-2) is still raging to this day. When will the COVID-19 pneumonia (COVID-19) it caused become endemic is everyone’s concern.


On July 5, 2022, Yale University School of Medicine Caroline Zeiss and her team published a paper entitled : Modeling pandemic to endemic patterns of SARS-CoV-2 transmission using Research paper on parameters estimated from animal model data .

The study predicts that the COVID-19 epidemic may complete the transition to an endemic epidemic within two years using an animal coronavirus reinfection model .


Yale University predicts that COVID-19 may turn into an endemic disease in two years


The epidemic trajectory of the COVID-19 epidemic will be determined by the non-eliminating immunity caused by the virus and the evolutionary trend of mutant strains.

Because of the cross-species transmission characteristics of SARS-CoV-2, mammals, including rodents, are susceptible to the virus and follow a pandemic-to-endemic trajectory from non-eliminating immunity.

This means that both humans and animals initially have fairly good immunity, but both are relatively weakened.

Therefore, even if a person or animal is vaccinated or infected with the virus, it can be reinfected with the virus.


Over the past two years, scientists have gradually discovered that humans have developed non-eliminating immunity to SARS-CoV-2, and that people who are already infected or vaccinated are still at risk of reinfection.

Therefore, scientists do not expect SARS-CoV-2 to disappear anytime soon.


Given that animal and human coronaviruses are very similar, collecting relevant data from animals provides an opportunity to better understand the potential trajectories of SARS-CoV-2.


In the new study, researchers looked at how a sialadenitis virus (SDAV) , which causes a human-like common cold , spreads in a population of rats.

SDAV is a highly contagious member of the betacoronavirus genus that causes transient respiratory disease in rats.


The team created a model of SDAV exposure in rats to simulate exposure to SARS-CoV-2 in the U.S. population.

In the United States, the majority of the population is naturally exposed to the risk of SARS-CoV-2, whether vaccinated or not.

The researchers also recreated the different types of exposures Americans experience in rats: some animals were in close contact with infected rats (a high risk of infection) ; cage (low risk of infection) .


The researchers observed that the infected animals developed upper respiratory tract infections.

After three to four months of recovery, the rats were re-exposed to SDAV virus.

The reinfection rate showed that natural exposure produced a mixed level of immunity, with those rats that were “in close contact” with stronger immunity, and those placed in virus-contaminated cages had a higher rate of reinfection.


Taken together, the study suggests that some people develop better immunity than others in the event of a natural infection.

People also need to be vaccinated, as this creates predictable immunity.

Through vaccination and in the case of natural infection, the population accumulates broad immunity, thereby driving the steady transition from COVID-19 to an endemic disease.


Subsequently, the researchers used these data to model and predicted that the median time required for SARS-CoV-2 to spread in the United States was 1,437 days, which means that from the start of the COVID-19 epidemic in March 2020, COVID-19 pneumonia will take no It turns into an endemic by 4 years .

In this scenario, 15.4% of the U.S. population remains susceptible to SARS-CoV-2.


Yale University predicts that COVID-19 may turn into an endemic disease in two years


The researchers stress that the model predicts a median time of 4 years, but that it may take longer to reach endemicity because SARS-CoV-2 may evolve more harmful mutant strains stage.


Professor Caroline Zeiss , the corresponding author of the study , said that the new coronavirus will continue to spread.

Therefore, it is very important to pay attention to vulnerable groups. We cannot assume that once endemic status is reached, everyone is safe.


She also said that the new coronavirus is very unpredictable and it is constantly mutating to make it more pathogenic.

More likely, though, the virus’s infectivity has increased, but its pathogenicity may have declined.

This means that the new coronavirus is easily spread from person to person, but is less likely to cause serious illness, like the common cold.


There is precedent for this trajectory, such as the pandemic of the late 19th century mentioned at the beginning of the article.

In addition, the researchers also observed reduced pathogenicity of the virus in the transition from pandemic to endemic in porcine coronaviruses.

And nearly all commercial flocks worldwide are vaccinated against an endemic respiratory coronavirus that has been around since the 1930s.


Professor Caroline Zeiss said long-term experience with coronavirus infections in other animals could help us find a way to coexist with the new coronavirus.

We are a global community, and we don’t yet know where the virus will mutate next.

We could easily disrupt this process with new mutant strains until the transition to stable endemic disease is achieved globally, but the overall picture should be optimistic. Covid-19 will be in an endemic stable state for the next year or two.


Paper link :

Yale University predicts that COVID-19 may turn into an endemic disease in two years

(source:internet, reference only)

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Important Note: The information provided is for informational purposes only and should not be considered as medical advice.