What if COVID-19 never goes away?

This question about what happened next drew Jennie Lavine, a psychologist at Emory University, who is a co-author of a recent paper in Science that predicted a relatively optimistic situation: After most have been exposed to the virus – either through vaccination or disease survival – the pathogen will continue to “circulate, but will usually only develop a mild illness,” like a common cold.

While immunity acquired from other coronaviruses – such as those caused by the common cold or SARS or MERS – declines over time, symptoms of relapse tend to be milder than the first illness, he said. Ottar Bjornstad, co-author of the paper Science that studies viruses at Pennsylvania State University.

“Adults don’t usually get really bad symptoms if they’ve already been exposed,” he said.

The prediction in the Science paper is based on a study of how other coronaviruses have been transmitted over time and assumes that SAR-CoV-2 is increasing, but not rapidly or rapidly. radical.

The 1918 flu pandemic could provide information on the COVID-19 course. That pathogen was an H1N1 virus with genes derived from birds, not coronavirus. At the time, vaccines were not available. The U.S. Centers for Disease Control and Prevention estimates that a third of the world’s population has been captured. Eventually, after an infected person dies or becomes immune, the virus stops spreading rapidly. It later moved to a less robust form, which experts say will rotate seasonally.

“The offspring of flu pandemics usually develop into the milder seasonal flu viruses that we have been experiencing for several years,” said Stephen Morse, who studies viruses at Columbia University.

It is not yet clear how future mutations in SARS-CoV-2 will shape the pathway of the conventional disease.

As new changes emerge – some more contagious, some more brutal and some less responsive to vaccines – scientists are being reminded that they do not yet know about the future of the virus, he said. Mark Jit, who studies viruses at the London School of Hygiene and Tropical Medicine.

“We’ve only known about this virus for about a year, so we still don’t have data to show its behavior over five or 10 years,” he said.

Of the more than 12 billion coronavirus vaccine injections made in 2021, rich countries have bought about 9 billion, and many have options to buy more. This inequality is a threat because it will make poor countries wait longer for the vaccine, during which time the disease will continue to spread and kill people, said John Mackay, who will be studying viruses at the University of Queensland.

It is worrying that some vaccines are so effective against the new strains, but because the sights offer some protection, vaccines could still be used to stop the virus from spreading. spread, Ashley St. said. John, who studies immune systems at Duke-NUS Medical School in Singapore.

Dr. Gagandeep Kang, an expert on infectious diseases at the Christian Medical College at Vellore in southern India, said the evolution of the virus raises new questions: How high is the virus at the new strain? Do countries have to get vaccinated from scratch? Or could a booster dose be given?

“These are issues that you need to address in the future,” Kang said.

The future of the coronavirus may be different from other infectious diseases that have been hit largely by vaccines that provide lifelong immunity – such as measles. The spread of measles falls after many people are vaccinated.

But the dynamic changes over time with new births, so diseases tend to come in circles, explained Dr. Jayaprakash Muliyil, who studies epidemics and advises India on virus testing .

Unlike measles, children with COVID-19 infection do not always show obvious symptoms and may pass the disease to vulnerable adults. That means countries cannot let down the guard, he said.

Another unknown is the long-term effect of COVID-19 on patients who survive but are incapacitated for months, Kang said.

The “measure of this damage” – how many people are unable to do manual work or are so tired that they cannot concentrate – is crucial to fully understanding the consequences of the disease.

“We haven’t had many diseases that have affected people at a scale like this,” she said.