NEW DELHI (AP): What if COVID-19 never goes away?
Experts say some version of the disease is likely to last for years. But what will be in the future is less clear.
Will the coronavirus, which has already killed more than 2 million people worldwide, be finally eliminated by a global vaccination campaign, such as smallpox? Will the new dangerous variants evade vaccines? Or will the virus last for a long time, turning into a mild nuisance, like the common cold?
Eventually, the virus known as SARS-CoV-2 will become “one more animal in the zoo,” joining the many other infectious diseases that humanity has learned to live with, Dr. T. Jacob John, who studies viruses and was at the helm of India’s efforts to combat polio and HIV / AIDS.
But no one knows for sure. The virus evolves rapidly and new variants appear in different countries. The risk of these new variants became apparent when Novavax Inc. found that the company’s vaccine didn’t work so well against mutated versions circulating in Britain and South Africa. The more the virus spreads, experts say, the more likely a new variant will be able to evade current testing, treatments and vaccines.
For now, scientists agree on the immediate priority: vaccinating as many people as possible. The next step is less safe and depends largely on the strength of the immunity offered by natural vaccines and infections and how long it lasts.
“Will people be frequently subject to repeated infections? We don’t have enough data to know yet, “said Jeffrey Shaman, who studies viruses at Columbia University. Like many researchers, he believes vaccines are unlikely to confer lifelong immunity.
If humans are to learn to live with COVID-19, the nature of this coexistence depends not only on the duration of immunity, but also on the evolution of the virus. Will it mutate significantly each year, requiring annual vaccines, such as the flu? Or will it appear every few years?
This question about what happens next attracted Jennie Lavine, a virologist at Emory University, who is the co-author of a recent article in Science this projected a relatively optimistic scenario: after most people have been exposed to the virus (either through vaccination or surviving infections), the pathogen “will continue to circulate, but will only cause mild illness,” as a routine cold.
Although acquired immunity from other coronaviruses, such as those that cause the common cold or SARS or MERS, decreases over time, the symptoms of reinfection are usually milder than the first disease, Ottar Bjornstad said. , co-author of the paper Science that studies viruses. at Pennsylvania State University.
“Adults usually don’t have very bad symptoms if they’ve 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 rapidly or radically.
The 1918 flu pandemic could provide clues over the course of COVID-19. This pathogen was an H1N1 virus with genes originating in birds, not a coronavirus. At that time, no vaccines were available. The U.S. Centers for Disease Control and Prevention estimates that one-third of the world’s population became infected. Finally, after infected people died or developed immunity, the virus stopped spreading rapidly. It was later transformed into a less virulent form, which experts say continues to circulate seasonally.
“Very often the offspring of flu pandemics become the mildest seasonal flu viruses we have experienced for many years,” said Stephen Morse, who studies viruses at Columbia University.
It is still unclear how future SARS-CoV-2 mutations will shape the current disease trajectory.
As new variants appear (some more contagious, some more virulent, and some possibly less sensitive to vaccines), scientists are reminded how much they still do not know 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 now, so we still don’t have data to show its behavior for five or ten years,” he said.
Of the more than 12 billion coronavirus vaccines that were 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 cause poorer countries to have to wait longer to get the vaccine, a period during which the disease will continue to spread and kill people, said Ian MacKay, who studies viruses at the University. of Queensland.
That some vaccines appear to be less effective against new strains is worrisome, but since the shots offer some protection, the vaccines could still be used to slow or stop the spread of the virus, Ashley St. said. John, who studies immune systems 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 have to be vaccinated again from scratch? Or can a booster dose be given?
“These are questions he will have to address in the future,” Kang said.
The future of coronavirus may contrast with other highly contagious diseases that have received much of the vaccines that provide lifelong immunity, such as measles. The spread of measles decreases after vaccination of many people.
But the dynamic changes over time with new births, so outbreaks usually occur in cycles, said 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 can transmit the disease to vulnerable adults. That means countries cannot lower their guard, he said.
Another unknown is the long-term impact of COVID-19 on patients who survive but are disabled for months, Kang said.
“Quantifying this damage” (how many people cannot do manual labor or are so exhausted that they cannot concentrate) is key to understanding the full consequences of the disease.
“We haven’t had many diseases that have affected people on a scale like that,” he said.
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Larson reported from Washington.
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The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.