NEW DELHI (AP) – What if COVID-19 never disappears?
Experts say that a certain version of the disease is likely to persist for years. But what it will look like in the future is less clear.
Will the coronavirus, which has already killed more than 2 million people worldwide, eventually be eliminated through a global vaccination campaign, such as smallpox? Will new dangerous variants steal vaccines? Or will the virus stay for a long time, turning into a slight annoyance, like the usual cold?
Eventually, the virus known as SARS-CoV-2 will become yet another “zoo animal,” joining many other infectious diseases that humanity has learned to live with, predicted Dr. T. Jacob John , which studies viruses and is at the helm of India’s efforts to fight polio and HIV / AIDS.
But no one knows for sure. The virus is evolving rapidly and new variants are emerging in different countries. The risk of these new variants was highlighted when Novavax Inc. found that the company’s vaccine was not working as well against mutant versions circulating in the UK and South Africa. The more the virus spreads, experts say, the more likely it is that a new variant will become able to avoid current tests, treatments and vaccines.
For now, scientists agree with the immediate priority: vaccinate as many people as possible. The next step is less safe and largely depends on the strength of the immunity offered by vaccines and natural infections and how long they last.
“Will people be frequently exposed to repeated infections? We don’t have enough data yet 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 low.
If people 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 the evolution of the virus. Will it move significantly each year, requiring annual vaccines such as the flu? Or will it appear every few years?
This question about what’s next has attracted Jennie Lavine, a virologist at Emory University, who is the co-author of a recent paper in Science. who projected a relatively optimistic scenario: after most people have been exposed to the virus – either by vaccination or by surviving infections – the pathogen “will continue to circulate, but will mostly cause only mild illness”, such as a cold routine.
While immunity to 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 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 Science is based on an analysis of how other coronaviruses have behaved over time and assumes that SAR-CoV-2 continues to evolve, but not rapidly or radically.
The 1918 flu pandemic could provide clues about the evolution of COVID-19. This pathogen was an H1N1 virus with genes from birds, not a coronavirus. At that time, there were no vaccines available. The US Centers for Disease Control and Prevention estimates that a third of the world’s population has become infected. Eventually, after infected people died or developed immunity, the virus stopped spreading rapidly. It later moved to a less virulent form, which experts say continues to circulate seasonally.
“Very often the descendants of flu pandemics become the milder seasonal flu viruses we have been experiencing for many years,” said Stephen Morse, who studies viruses at Columbia University.
It is not yet clear how future SARS-CoV-2 mutations will shape the current disease trajectory.
As new variants emerge – some more contagious, some more virulent and some less receptive to vaccines – scientists are being reminded of how much they 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 don’t have data on its behavior over five or 10 years yet,” he said.
Of the more than 12 billion coronavirus vaccines made in 2021, rich countries have bought about 9 billion, and many have options to buy more. This inequity is a threat because it will lead to poorer countries having to wait longer for the vaccine, as the disease continues to spread and kill people, said Ian MacKay, who studies viruses at the University of Queensland.
The fact that some vaccines appear to be less effective against new strains is worrisome, but since vaccines provide some protection, vaccines could still be used to slow or stop the spread of the virus, Ashley St. said. John, who is studying the immune system at Duke-NUS Medical School in Singapore.
Dr. Gagandeep Kang, an infectious disease expert at Christian Medical College in Vellore, southern India, said the evolution of the virus raises new questions: at what stage does the virus become a new strain? Will countries need to be re-vaccinated from scratch? Or could a booster dose be given?
“These are questions you will have to address in the future,” Kang said.
The future of coronavirus may contrast with other highly contagious diseases that have been largely killed by vaccines that provide lifelong immunity – such as measles. The spread of measles decreases after many people have been vaccinated.
But the dynamic changes over time with new births so that outbreaks tend to occur 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 show clear symptoms and may continue to transmit the disease to vulnerable adults. That means countries can’t 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, Kang said.
“Quantifying this damage” – how many people cannot do manual labor or are so exhausted that they cannot concentrate – is essential to understanding the full consequences of the disease.
“We haven’t had a lot of diseases that have affected people on a scale like this,” she said.
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Larson reported from Washington.
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