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 are rolled out around the world, many look forward to achieving “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’s seen as a path to normalcy, and something doctors and political leaders often talk about when talking about beating Covid-19.
While doubts exist as to whether herd immunity is possible, medical experts who spoke with CNBC say it can be achieved. However, they point to a difficult road ahead as it will be challenging to maintain a high level of immunity.
“I think sooner or later every part of the world will achieve immunity to herds,” said Benjamin Cowling, head of the division of epidemiology and biostatistics at the School of Public Health at the University of Hong Kong. Different communities can get there through vaccinations, infections, or a combination of both, he added.
Not everyone agrees.
An article last month in the scientific journal Nature outlined five reasons why it is not possible to achieve immunity to herds. The report said the 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 transmission blocking vaccine. If we don’t, the only way to get herd immunity in the population is to give everyone the vaccine. to give. “
Herd Immunity: “Complicated” but possible
Health experts speaking with CNBC acknowledged that the factors discussed in the Nature article can hinder progress towards herd immunity – but they said they believe it is still within reach.
“We’re not trying to eradicate it, we’re trying to stop uncontrolled community transmission. In that sense, we can achieve (herd immunity),” said Dale Fisher, a professor of infectious diseases at the National University of Yong Loo Lin School of Medicine. Singapore.
Dr. Anthony Fauci, chief medical adviser to President Joe Biden, has said 75% to 85% of people must be vaccinated to create an “umbrella” of immunity that prevents the virus from spreading. Fisher estimates the figure to be around 70%.
“Getting to … 70% is possible, but there are many threats,” he said, explaining that the percentage of a population immune to Covid-19 would drop if immunity wanes. make the vaccines less effective.
“Herd immunity is a very beautiful and conceptual thing to strive for, but it’s more complicated than that,” he said during a phone call. “If you want to call a magic number of about 70%, all I’m saying is that it is very difficult to achieve and maintain.”
Herd immunity may not be permanent, it may be relatively short-lived.
Benjamin Cowling
School of Public Health at the University of Hong Kong
Cowling agreed that there is “no guarantee” that immunity levels would remain high in the long run. “Herd immunity may not be permanent, it may be something that is relatively short-lived,” he said.
Still, it’s something the world can work towards, he added, stressing that booster shots can help if protection is lost.
Return to ‘normal’
It may take three to five years for the world to return to a “perfectly normal state,” said Carlos del Rio, a professor of medicine at Emory University School of Medicine.
“There are still a lot of broadcasts happening around the world and I think it will take some time for that to change,” he told CNBC’s “Street Signs Asia” Monday.
The World Health Organization warned this week that the pandemic is “growing exponentially,” and more than 4.4 million new Covid-19 cases were reported in the past week.
The bureau’s technical leader for Covid-19, Maria Van Kerkhove, said the world had reached a “critical point in the pandemic.”
“Vaccines and vaccinations are coming online, but they are not available in every part of the world yet,” she added.
Fisher said the world is still “very vulnerable to major outbreaks,” but cases could be sporadic within five or ten years. Meanwhile, there will be a transition period.
“Herd immunity is not a binary phenomenon,” he said. “Most people think you have it or you don’t, but there is clearly gray in between.”
Cowling said he thinks Covid’s greatest risk will be in the next 12 months, but the threat will diminish after that as vaccines are rolled out.
“What I would expect in the coming years is that the virus will still circulate, it will be endemic, but it will not pose a major threat to public health anymore,” he said.
– CNBC’s Berkeley Lovelace contributed to this report.