Researchers from the Yale School of Medicine in the US studied mice, which, like humans, are susceptible to the coronavirus to better understand when the COVID pandemic will end.
In the past two years, scientists have come to see that SARS-CoV-2 yields non-sterile immunity. People who have been infected or vaccinated are still at risk of reinfection. So experts are hopeful that the virus will not go away anytime soon.
“Coronaviruses are very unpredictable, so there may be a mutation that makes it more pathogenic,” Zeiss said.
“However, the more likely scenario is that we see an increase in transmissibility and a potential decrease in pathogenicity,” He added.
what the study says
The researchers noted that diseases such as the common cold and flu have become endemic in the human population, meaning everyone gets them occasionally, but for most people, they are not particularly harmful.
The reason, Zeiss said, is that with natural infection, some individuals will develop better immunity than others.
People also need vaccination, which is introduced through a prescribed dose and produces predictable immunity.
However, the study showed that with both vaccination and natural exposure, populations accumulate widespread immunity that pushes the virus toward endemic stability.
Why Mice?
Animals such as pigs and chickens also live with endemic coronaviruses, he said, and identified a major factor in the spread of animal and human coronaviruses, known as non-sterile immunity.
“This means there is a fairly good immunity initially, but relatively quickly diminishes,” said Carolyn 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 person has been vaccinated or infected, they will become susceptible again,” Zeiss said.
how the research was done
By collecting data on coronavirus reinfection rates in mice, they were able to model the possible trajectory of COVID-19.
Zeiss and his colleagues looked at how the coronavirus that causes the common cold in humans was transmitted through a rat population.
The researchers modeled an exposure scenario similar to human exposure in the US, where a portion of the population has been vaccinated against COVID-19 and where people are exposed to natural exposure to SARS-CoV-2.
They also reproduced a variety of exposures experienced by people in the US, with some animals exposed through close contact with an infected rat (high risk of infection) and others exposed to an infected rat (low risk). After staying in, he was kept in a cage. of infection).
Infected animals contracted upper respiratory tract infections and then recovered. After three to four months, the mice were reinfected and exposed to the virus again.
Re-infection rates showed that natural exposures elicited a mix of immune levels, those exposed to more virus through close contact with those with stronger immunity, and those kept in a contaminated cage, including There is a high rate of re-infection.
The team then used this data to inform mathematical models, finding that it could take an average of 1,437 days for SARS-CoV-2 to become endemic in the US, or just over four years from the start of the pandemic in March 2020. There may be less time.
In this scenario, according to the model, 15.4% of the population would be susceptible to infection at any time after the endemic phrase was reached.
“The virus is going to spread continuously. Therefore it will be important to take into account the more vulnerable groups. We cannot assume that once we reach the endemic state that everyone is safe,” Zeiss said.
That said, four years is the average time estimated by the model, so it may take even longer to reach the spatial stage.
The researchers said this did not take into account mutations that could make SARS-CoV-2 more harmful.
(with inputs from PTI)