People are holding hands on Fifth Avenue amid the April 10, 2021 coronavirus pandemic in New York.
Noam Galai | Getty Images Entertainment | Getty Images
As Covid vaccines are spread around the world, many are looking forward to reaching “herd immunity” – when the disease is no longer transmitted quickly because the majority of the population is immune from vaccinations or after being infected.
It is seen as a path to normalcy and something that doctors and political leaders often discuss when talking about the defeat of Covid-19.
Although there have been doubts about the possibility of staff immunity, medical experts who spoke to CNBC say it can be done. However, they indicate a hard road ahead, as sustaining a high level of immunity will be a challenge.
“I think every part of the world will get immunity sooner or later,” said Benjamin Cowling, head of the epidemiology and biostatistics division at the University of Hong Kong’s School of Public Health. Different communities can get there through vaccinations, infections or a combination of both, he added.
Not everyone agrees.
An article in the scientific journal Nature last month highlighted five reasons why herd immunity cannot be achieved. The report said 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, then the only way to get herd immunity in the population is to give everyone the vaccine.”
Herd immunity: “complicated”, but possible
Health experts who spoke to CNBC acknowledged that the factors raised in the Nature article could impede progress toward staff immunity – but said they believe it is still within reach.
“We are not trying to eradicate it, we are trying to stop the transmission of the community without control. In this sense, we can get (herd immunity),” said Dale Fisher, a professor of infectious diseases at Yong Loo Lin National University of Medicine in Singapore.
Dr. Anthony Fauci, chief medical adviser to President Joe Biden, said 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 about 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 decrease if immunity disappears. makes vaccines less effective.
“The herd’s immunity is something very beautiful and conceptually to be pursued, but it is more complicated than that,” he said during a call. “If you want to call a magic number of about 70%, then all I’m saying is that it’s very hard to reach and maintain.”
The herd’s immunity may not be permanent, it may be something relatively short-term.
Benjamin Cowling
University of Hong Kong School of Public Health
Cowling agreed that there was “no guarantee” that the level of immunity would remain high in the long run. “The herd’s immunity may not be permanent, it may be something relatively short-term,” he said.
However, it is something the world can work towards, he added, stressing that booster photos can help if there is a loss of protection.
Returning to “normal”
It could take three to five years for the world to return to a “totally normal state,” said Carlos del Rio, a professor of medicine at Emory University School of Medicine.
“There are still a lot of broadcasts globally and I think it will take some time before this change,” he told CNBC’s “Street Signs Asia” on Monday.
The World Health Organization warned this week that the pandemic was growing exponentially and that more than 4.4 million new cases of Covid-19 had been reported in the previous week.
The agency’s technical leader for Covid-19, Maria Van Kerkhove, said the world had reached a “critical point in the pandemic.”
“Vaccines and vaccinations come online, but they are not yet here in every part of the world,” she added.
Fisher said the world is still “very vulnerable to huge outbreaks” – but cases could be sporadic in five to 10 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 – but obviously there’s gray between them.”
Cowling said he believes the highest risk of Covid will be in the next 12 months, but the threat will subside thereafter as vaccines are released.
“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 be a major threat to public health,” he said.
– CNBC’s Berkeley Lovelace contributed to this report.