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Travelers wear face masks at a train station after the coronavirus outbreak in Beijing, China. January 13, 2021. REUTERS / Thomas Peter

As millions of people get vaccinated against the coronavirus, and the end of the pandemic seems to finally be looming, researchers are making speculation about what a post-vaccine world might look like, and what they envision is comforting.

According to a study published Tuesday in the journal Science, the coronavirus is here to stay, but once most adults are immune (after natural contagion or vaccination) the virus will be no more dangerous threat than the common cold.

Right now the virus is a funereal threat because it is an unknown pathogen that can overwhelm the adult immune system, which has not been trained to fight it. That will no longer be the case once everyone has been exposed to the virus or the vaccine.

On the other hand, children are constantly dealing with new pathogens invading their body, and that is one of the reasons they are more adept than adults at defending themselves against the coronavirus. The study suggests that over time, the virus will only be a cause for concern in children under the age of 5, and even in them it will only cause simple colds, or no symptoms at all.

In other words, the coronavirus will become “endemic”, a pathogen that circulates at low levels and only rarely causes serious disease. “The time it takes to reach this type of endemic state depends on how quickly the disease spreads and how quickly the vaccine is given,” said Jennie Lavine, a postdoctoral fellow at Emory University in Atlanta, who led the study. “So really, the most important thing is to get everyone exposed to the vaccine for the first time as soon as possible.”

Lavine and his colleagues analyzed the other six human coronaviruses – four that cause the common cold, in addition to SARS and MRSA viruses – for clues about the future of the new pathogen.

All four common cold coronaviruses are endemic and cause only mild symptoms. Severe acute respiratory syndrome and Middle East respiratory syndrome, which appeared in 2003 and 2012, respectively, made people seriously ill, but were not widely spread.

Although all of these coronaviruses produce a similar immune response, the new virus is more like the endemic coronaviruses of the common cold, according to the hypothesis of Lavine and his colleagues.


Re-analyzing data from a previous study, they found that the first infection of the common cold coronavirus occurs on average between 3 and 5 years. After that age, people can be infected over and over again, which increases their immunity and keeps viruses circulating, but they do not get sick.

Researchers foresee a similar future for the new coronavirus.

Depending on how quickly the virus spreads and the strength and duration of the immune response, it will take a few years to decades of natural contagion for the coronavirus to become endemic, Lavine said.

Without a vaccine, the quickest path to endemic is also the worst. The price of immunity for the population would be widespread disease and many deaths along the way.

Vaccines alter that calculation completely. The faster people can be immunized the better. Efficient vaccine deployment could shorten the timeframe to a year, or even just six months, for the coronavirus to become an endemic infection.

Still, vaccines are unlikely to eradicate the coronavirus, Lavine predicted. The virus will become a permanent inhabitant of our environment, although more benign.

Other experts pointed out that this scenario is not only plausible but probable.

“I totally agree with the overall intellectual articulation of the trial,” said Shane Crotty, a virus expert at the La Jolla Institute of Immunology in San Diego. If vaccines prevent people from transmitting the virus, “then it will become very much like the measles scenario, where you vaccinate everyone, including children, and you really stop seeing that the virus infects people. Crotty said.

It is more plausible that vaccines prevent disease, but not necessarily infection and transmission, he added. That means that the coronavirus will continue to circulate.

“The vaccines we have right now are unlikely to provide sterilizing immunity,” which is necessary to prevent infection, said Jennifer Gommerman, an immunologist at the University of Toronto.

The natural coronavirus infection produces a strong immune response in the nose and throat, but with current vaccines, Gommerman said, “you do not generate a natural immune response in the upper respiratory tract, but an injection in the arm.” This increases the likelihood that infections will continue, even after vaccination.

Ultimately, Lavine’s model is based on the assumption that the new coronavirus is similar to the common cold coronaviruses, but that hypothesis may not be supported, warned Marc Lipsitch, a public health researcher at the TH School of Public Health. Chan of Harvard University in Boston.

“The same may or may not happen with other coronavirus infections because we have not seen what these can do to an older and ‘naive’ person,” Lipsitch said. (Naif refers to an adult whose immune system has not been exposed to the virus.)

Another viable scenario, he added, is that the virus could come to resemble seasonal flu, which is mild in some years and more lethal in others. New variants of the coronavirus that avoid the immune response could also complicate the picture.

“I would bet a lot of money on his prediction that it is going to look like a common cold coronavirus,” Lipsitch concluded, “but I don’t think it’s completely guaranteed.”


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