The future of the coronavirus? Nothing worse than a cold

As millions of people are inoculated with the coronavirus and the end of the pandemic finally appears to appear, scientists contemplate what a post-vaccine world might look like – and what they see is heartwarming.

The coronavirus is here to stay, but once most adults are immunized – either through natural infection or vaccination – the virus will not be more of a threat than the common cold, according to a study published in the Science review this week. The virus is a grim threat now because it is an unknown pathogen that can overwhelm the adult immune system, which has not been trained to fight it. This will no longer be the case once everyone has been exposed to the virus or vaccine.

Children, on the other hand, are constantly confronted with new pathogens in their bodies, and this is one of the reasons they are better able than adults to fight the coronavirus. Ultimately, the study suggests the virus will only be of concern in children under the age of five, subjecting them to even simple sniffles – or no symptoms.

Depending on how quickly the virus spreads, and the strength and longevity of the immune response, it would take anywhere from a few years to decades of natural infections for this coronavirus to become endemic.

In other words, the coronavirus will become “endemic”, a pathogen that circulates at low levels and only rarely causes serious illness. “The time it takes to get to this type of endemic condition depends on how quickly the disease spreads and how quickly the vaccination is rolled out,” says Jennie Lavine, postdoctoral researcher at Emory University, Atlanta, who led the study. “So really the point of the game is to get everyone exposed to the vaccine for the first time as quickly as possible.”

Lavine and his colleagues looked to the other six human coronaviruses – four that cause colds, plus the Sars and Mers viruses – for clues about the fate of the new pathogen. The four common cold coronaviruses are endemic and produce only mild symptoms. Severe Acute Respiratory Syndrome and Middle East Respiratory Syndrome, which appeared in 2003 and 2012, respectively, made people seriously ill, but they did not spread widely.

While all of these coronaviruses produce a similar immune response, the new virus is more similar to endemic cold coronaviruses, assume Lavine and his colleagues. Re-analyzing data from a previous study, they found that the first cold coronavirus infection occurs on average between three and five years old. After this age, people can get infected again and again, which boosts their immunity and keeps viruses circulating. But they don’t get sick.

Researchers predict a similar future for the Covid-19 virus. Depending on how quickly the virus spreads and the strength and longevity of the immune response, it would take a few years to decades of natural infections for this coronavirus to become endemic, Lavine says.

Without a vaccine, the quickest path to endemic status is also the worst. The cost of the population’s immunity would be widespread illness and death along the way. Vaccines completely change this calculation. The faster people can be vaccinated, the better. An effective roll-out of vaccination could shorten the timeframe for the Covid-19 virus to become an endemic infection by a year, or even six months. Still, vaccines are unlikely to eradicate it, predicts Lavine. The virus will become a permanent, albeit more benign, inhabitant of our environment.

Other experts claim that this scenario is not only plausible but probable. “I completely agree with the overall intellectual construction of the article,” says Shane Crotty, a virus expert at the La Jolla Institute for Immunology, in San Diego. If vaccines keep people from spreading the virus, “it looks a lot more like the measles scenario, where you vaccinate everyone, including children, and you don’t really see the virus infecting people anymore,” Crotty says.

Vaccines are more likely to prevent disease – but not necessarily infection and transmission, he adds. And that means the Covid-19 virus will continue to circulate. “The vaccines we have now are unlikely to provide sterilizing immunity,” the type needed to prevent infection, says Jennifer Gommerman, an immunologist at the University of Toronto.

Natural infection with the coronavirus produces a strong immune response in the nose and throat. But with the current vaccines, says Gommerman, “you don’t get a natural immune response in the upper respiratory tract, you get an injection in the arm.” This increases the likelihood that infections will still occur, even after vaccination.

Ultimately, Lavine’s model is based on the assumption that the new coronavirus is similar to the common cold coronavirus. But that hypothesis might not hold, warns Marc Lipsitch, a public health researcher at Harvard TH Chan School of Public Health, in Boston.

Another plausible scenario is that the virus could look like the seasonal flu, which is mild in some years and more fatal in others.

“Other coronavirus infections may or may not be applicable because we haven’t seen what these coronaviruses can do to an older, naive person,” Lipsitch says. (Naive refers to an adult whose immune system has not been exposed to the virus.) Another plausible scenario, he says, is that the virus could resemble seasonal flu, which is mild in some years and more deadly in others. New variants of the Covid-19 virus that elude the immune response can also complicate the picture.

“Their prediction that this is becoming like coronavirus from the common cold is where I would put a lot of my money,” Lipsitch says. “But I don’t think it’s absolutely guaranteed.”

When and how the common cold coronaviruses first appeared is a mystery, but since the emergence of the new coronavirus, some scientists have revisited a theory that a pandemic in 1890, which killed an estimated one million people worldwide. , could have been caused by OC-43, one of the four common cold coronaviruses.

“People suggested that the human population developed low-grade and broad immunity against OC-43 which ended the pandemic,” says André Veillette, immunologist at the Clinical Research Institute of Montreal, Canada . “This coronavirus is currently circulating widely in the community in a rather peaceful manner.” – New York Times