Washington: De COVID-19 According to a model study in rats, the disease can reach an endemic stage in the US in at least two years.
The researchers noted that illnesses such as the common cold and flu have become endemic in human populations, meaning everyone gets them every now and then, but for most people they aren’t particularly harmful.
To gain a better understanding of when and how COVID-19 could become endemic, researchers at the Yale School of Medicine in the US turned to rats, which, like humans, are also susceptible to coronaviruses.
By collecting data on the re-infection rates of the coronavirus in rats, they were able to model the potential trajectory of COVID-19.
Animals such as pigs and chickens also live with endemic coronaviruses, and a key factor identified in the spread of both animal and human coronaviruses is their tendency to evoke what is known as non-sterilizing immunity, they said.
“It means there’s pretty good immunity initially, but it wears off relatively quickly,” said Caroline Zeiss, a professor at Yale School of Medicine and senior author of the study, published Tuesday in the journal PNAS.
“And so even if an animal or a person is vaccinated or infected, they are likely to become susceptible again,” Zeiss said.
Over the past two years, scientists have come to realize that SARS-CoV-2 provides non-sterilizing immunity. People who are infected or vaccinated are still at risk of reinfection. Experts therefore expect that the virus will not disappear soon.
Zeiss and her colleagues observed how a coronavirus similar to one that causes the common cold in humans was transmitted through rat populations.
The researchers modeled the exposure scenario to resemble human exposures in the US, where a portion of the population is vaccinated against COVID-19 and where people are still exposed to natural exposure to SARS-CoV-2.
They also reproduced the different types of exposure that humans experience in the US, with some animals exposed through close contact with an infected rat (high risk of infection) and others exposed by placing them in a cage once occupied by an infected rat. rat (low risk of infection).
Infected animals contracted an upper respiratory tract infection and subsequently recovered. After three to four months, the rats were then reorganized and re-exposed to the virus.
The reinfection rates showed that natural exposure produced a mix of immunity levels, with those exposed to more virus through close contact having stronger immunity, and those placed in an infected cage having higher reinfection rates.
The takeaway, Zeiss said, is that with natural infection, some individuals will develop better immunity than others.
Humans also need vaccination, which is offered through a fixed dose and generates predictable immunity.
However, the study showed that with both vaccination and natural exposure, the population builds broad immunity that pushes the virus toward endemic stability.
The team then used this data to inform mathematical models, and found that the median time it could take for SARS-CoV-2 to become endemic in the US is 1,437 days, or just under four years from the start of the pandemic. in March 2020.
In this scenario, according to the model, 15.4 percent of the population would be susceptible to infection at some point after it reaches endemicity.
“The virus is constantly circulating. It is therefore important to take into account more vulnerable groups. We can’t assume that once we get to the endemic state, everyone will be safe,” Zeiss said.
Four years is the median time predicted by the model, she said, so it may take even longer to reach the endemic stage.
This does not account for mutations that could make SARS-CoV-2 more harmful, the researchers said.
“Coronaviruses are very unpredictable, so there could be a mutation that makes it more pathogenic,” Zeiss said.
“However, the most likely scenario is that we see an increase in transmissibility and a likely decrease in pathogenicity,” she added.
Also read: Now the head of Pak ISI is ordering commanders to stay away from politics
#COVID19 #endemic #stage #years #research #suggests