The virus may never disappear, but it can turn into a mild nuisance

NEW DELHI – What if COVID-19 never leaves?

Experts say that some version of the disease is likely to last for years. But how it will be in the future is less clear.

Will the coronavirus, which has killed more than 2 million people worldwide, be eliminated by a global vaccination campaign, such as smallpox? Will the new dangerous variants escape vaccines? Or will the virus last a long time, turning into a mild nuisance, like the common cold?

Eventually, the virus known as SARS-CoV-2 will become more “another animal in the zoo”, joining many other infectious diseases that humanity has learned to live with, predicted Dr. T. Jacob John, who studies viruses and he was in charge of India’s efforts to fight polio and HIV / AIDS.

But nobody knows for sure. The virus is evolving rapidly and new variants are emerging in different countries. The risk of these new variants was emphasized when Novavax Inc. found that the company’s vaccine did not work as well against mutant versions that circulated in Britain and South Africa. The more the virus spreads, experts say, the more likely is that a new variant becomes able to escape the current tests, treatments and vaccines.

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For now, scientists agree on the immediate priority: vaccinating as many people as possible as soon as possible. The next step is less certain and depends a lot on the strength of the immunity offered by vaccines and natural infections and on its duration.

“Will people often be subject to repeated infections? We still don’t have enough data to know, ”said Jeffrey Shaman, who studies viruses at Columbia University. Like many researchers, he believes that the chances of vaccines conferring lifelong immunity are minimal.

If humans need to learn to live with COVID-19, the nature of this coexistence depends not only on how long the immunity lasts, but also on how the virus evolves. Will it mutate significantly each year, requiring annual injections, such as the flu? Or will it appear every few years?

This question of what will happen next attracted Jennie Lavine, a virologist at Emory University, who co-authored a recent article in Science that projected a relatively optimistic scenario: after most people were exposed to the virus – either by vaccination or surviving infections – the pathogen “will continue to circulate, but mostly it will only cause mild illnesses”, like a routine cold.

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Although the acquired immunity from other coronaviruses – such as those that cause the common cold or SARS or MERS – decreases over time, symptoms of reinfection tend to be milder than the first disease, said Ottar Bjornstad, co-author of the paper. Science studying viruses at Pennsylvania State University.

“Adults tend not to have very bad symptoms if they have already been exposed,” he said.

The prediction in the Science article is based on an analysis of how other coronaviruses have behaved over time and assumes that SAR-CoV-2 continues to evolve, but not quickly or radically.

The 1918 flu pandemic may offer clues as to the course of COVID-19. This pathogen was an H1N1 virus with genes that originated in birds, not a coronavirus. At the time, there were no vaccines available. The United States Centers for Disease Control and Prevention estimates that one third of the world’s population has been infected. Eventually, after the infected people died or developed immunity, the virus stopped spreading quickly. He later mutated to a less virulent form, which experts say continues to circulate seasonally.

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“Very often the offspring of influenza pandemics become the mildest seasonal flu viruses we have experienced for many 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 path of the current disease.

As new variants emerge – some more contagious, some more virulent and some possibly less responsive to vaccines – scientists are reminded of how much they still don’t know about the future of the virus, 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 in five or ten years,” he said.

Of the more than 12 billion coronavirus vaccines being made in 2021, rich countries have bought about 9 billion, and many have options to buy more. This inequality is a threat as it will make poorer countries have to wait longer for the vaccine, during which the disease will continue to spread and kill people, said Ian MacKay, who studies viruses at the University of Queensland.

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It is worrying that some vaccines appear less effective against the new strains, but because the injections provide some protection, the vaccines can still be used to slow or prevent the spread of the virus, said Ashley St. John, who studies the immune system at Duke- NUS Medical School in Singapore.

Dr. Gagandeep Kang, an infectious disease specialist at Christian Medical College in Vellore, southern India, said that the evolution of the virus raises new questions: at what stage does the virus become a new strain? Will countries need to revaccinate from scratch? Or can a booster dose be given?

“These are questions that you will have to answer in the future,” said Kang.

The future of coronavirus may contrast with other highly contagious diseases that have been largely defeated by vaccines that provide lifelong immunity – such as measles. The spread of measles slows after many people are vaccinated.

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But the dynamics change over time with new births, so outbreaks tend to come in cycles, explained Dr. Jayaprakash Muliyil, who studies epidemics and advises India on virus surveillance.

Unlike measles, children infected with COVID-19 do not always have clear symptoms and can still transmit the disease to vulnerable adults. This means that countries cannot let their guard down, he said.

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

The “quantification of this damage” – how many people are unable to do manual work or are so exhausted that they cannot concentrate – is the key to understanding all the consequences of the disease.

“We didn’t have many diseases that affected people on a scale like this,” she said.

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Larson reported from Washington.

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The Associated Press Department of Health and Science receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.