People hold hands on Fifth Avenue amid the coronavirus pandemic on April 10, 2021 in New York City.
Noam Galai | Getty Images Entertainment | Getty Images
As Covid vaccines spread around the world, many hope to achieve “herd immunity,” when the disease is no longer transmitted quickly because the majority of the population is immune due to vaccinations or after -is infected.
It looks like a path to normalcy, and something doctors and political leaders often discuss when talking about defeating Covid-19.
While there have been doubts about whether herd immunity is possible, medical experts who spoke to CNBC say it can be achieved. However, they point out a difficult path ahead, as maintaining a high level of immunity will be a challenge.
“I think all parts of the world will achieve herd immunity sooner or later,” said Benjamin Cowling, head of the epidemiology and biostatistics division at the University of Hong Kong School of Public Health. He added that several communities can get there through vaccines, infections or a combination of both.
Not everyone agrees.
An article published last month in the scientific journal Nature explained five reasons why it would not be possible to achieve herd immunity. The report states that barriers to herd immunity include: new variants, declining immunity, and questions about whether vaccines actually prevent transmission.
Shweta Bansal, a mathematical biologist, told the publication: “Herd immunity is only relevant if we have a vaccine that blocks transmission. If we don’t, the only way to get herd immunity to the population is to administer it. the vaccine to everyone. “
Immunity to the herd: “complicated” but possible
Health experts who spoke to CNBC acknowledged that the factors raised in the Nature article could hinder progress toward herd immunity, but said they believe it is still within reach.
“We’re not trying to eradicate it, we’re trying to stop out-of-control community transmission. In that sense, we can achieve (herd immunity),” said Dale Fisher, a professor of infectious diseases at Yong Loo Lin National University School of Medicine. Singapore.
Dr. Anthony Fauci, chief medical adviser to President Joe Biden, has said that between 75% and 85% of people need to be inoculated to create an “umbrella” of immunity that prevents the virus from spreading. Fisher estimates that the figure is around 70%.
“Reaching … 70% is possible, but there are many threats,” he said, explaining that the percentage of a population that is immune to Covid-19 would fall if immunity fades. make vaccines less effective.
“Herd immunity is a very nice and conceptual thing, but it’s more complicated than that,” he said during a call. “If you want to call a magic number of 70%, all I’m saying is it’s very hard to get and keep.”
Herd immunity may not be permanent, it may be something that is relatively short-term.
Benjamin Cowling
Hong Kong University School of Public Health
Cowling agreed that there is “no guarantee” that the level of immunity will remain high in the long run. “Herd immunity may not be permanent, it may be something that is relatively short-term,” he said.
Still, it’s something the world can work towards, he added, stressing that reinforcing shots can help if there is a loss of protection.
Returning to normal
It could be three to five years before the world returns to a “totally normal state,” said Carlos del Rio, a professor of medicine at Emory University School of Medicine.
“There are a lot of broadcasts still going on worldwide and I think it will be a while before that changes,” he told CNBC’s “Street Signs Asia” on Monday.
The World Health Organization warned this week that the pandemic is “growing exponentially” and more than 4.4 million new cases of Covid-19 were recorded in the previous week.
The agency’s technical manager for Covid-19, Maria Van Kerkhove, said the world had reached a “critical point in the pandemic.”
“Vaccines and vaccines are published online, but they are not yet here in all parts of the world,” he added.
Fisher said the world is still “very vulnerable to huge outbreaks,” but cases may be sporadic in five to ten years. In the meantime, there will be a transition period.
“Herd immunity is not a binary phenomenon,” he said. “Most people think you either have it or you don’t have it, but it’s clear there’s gray in the middle.”
Cowling said he believes Covid’s biggest risk will be in the next twelve months, but the threat will diminish after that as vaccines are deployed.
“What I would expect in the coming years is that the virus will continue to circulate, it will be endemic, but it will no longer pose a major threat to public health,” he said.
– CNBC’s Berkeley Lovelace contributed to this report.