The omicron strain, which spreads much faster than previous forms of the coronavirus, is unlikely to help countries achieve so-called herd immunity to covid-19, i.e. that enough people acquire immunity so that the virus can no longer spread, say leading experts on the disease.
From the earliest days of the Covid-19 pandemic, public health experts have expressed the hope that it is possible to achieve herd immunity if a high enough percentage of citizens are vaccinated or infected.
Those hopes were dashed when the coronavirus rapidly mutated into new strains over the past year, allowing it to re-infect people who had received the vaccine or had had Covid-19.
Some health officials have revived the possibility of herd immunity since omicron emerged late last year, Reuters writes.
The fact that the strain spreads so quickly and causes milder symptoms could soon expose enough people to the SARS-COV-2 virus, in a less harmful way, and provide that protection, they argue.
Medical experts, however, note that the transmissibility of the omicron is aided by the fact that this strain is even better than its predecessors at infecting people who have been vaccinated or who have recovered from covid. This, according to the Reuters analysis, supports the evidence that the coronavirus will continue to find ways to break through our immune defenses.
"Reaching a theoretical point where transmission will stop is probably unrealistic given the experience we had during the pandemic," Dr. Olivier Le Paul, an epidemiologist at the World Health Organization (WHO), told Reuters.
This does not mean that there is no benefit from previous immunity. Instead of herd immunity, there is growing evidence that vaccines and past disease will help boost population immunity to Covid-19, making the disease less serious for those who are infected or reinfected, many experts interviewed by Reuters said.
"As long as population immunity lasts with this strain and future strains, we'll be happy and the disease will be treatable," said Dr. David Hayman, professor of infectious disease epidemiology at the London School of Hygiene and Tropical Medicine.
Existing covid-19 vaccines are designed primarily to prevent severe illness and death, not infection. But results from a clinical trial in late 2020 that showed the two vaccines were more than 90% effective against the disease initially raised hopes that widespread vaccination could largely suppress the virus, similar to how measles has been contained by immunization.
With the SARS-CoV-2 virus, two factors have since undermined that picture, said Mark Lipsic, an epidemiologist at the Harvard TH Chan School of Public Health.
"The first is that immunity weakens quite quickly, at least from the vaccines we currently have," he said.
Another is that the virus can mutate rapidly in ways that allow it to evade protection from vaccination or previous infection—even when immunity has not weakened.
"It's a game changer when vaccinated people can still transmit the virus and infect others," said Dr. David Wall, an infectious disease specialist at the University of North Carolina School of Medicine.
He cautioned that the assumption that omicron infection will increase protection, especially against a new strain that might emerge, is not correct. “Just because you've had an omicron, maybe you're protected from getting an omicron again, maybe,” Wall said.
This could be changed by developing vaccines that provide immunity to future strains or even multiple types of coronavirus, according to Pasi Pentinen, chief flu expert at the European Center for Disease Prevention and Control. However, this will take time.
However, as Reuters points out, the hope of gaining collective immunity as a ticket to return to normal life is hard to shake.
"One could read in the media that we will reach herd immunity when 60 percent of the population is vaccinated. That didn't happen. Then by 80 percent. That didn't happen either," Francois Ball, a professor of computational systems biology at University College London, told Reuters.
"As horrible as it sounds, I think we have to prepare for the fact that the vast majority, basically everyone, will be exposed to the SARS-CoV-2 virus," he said.
Global health experts expect the coronavirus to eventually become endemic, meaning it will appear regularly in certain areas according to established patterns. The appearance of the omicron, however, has raised questions about when exactly this might happen.
Europe is considering a new strategy: to embrace the virus
Some European countries, such as Spain, are making plans for when they can start treating Covid-19 as an endemic disease, but the World Health Organization and other officials warn that the world is nowhere close to declaring an end to the pandemic.
The idea is to move from a crisis regime to a control regime, treating the virus the same way countries treat the flu or measles. This means accepting that infections will happen and providing additional care for at-risk individuals and patients with complications, writes the Associated Press.
Spain's center-left Prime Minister Pedro Sanchez wants the European Union to consider similar changes as the omicron surge showed the disease is becoming less deadly.
The WHO believes that it is too early to think about any immediate change. The organization does not have clearly defined criteria for declaring covid-19 an endemic disease, but its experts have previously said that this will happen when the virus is more predictable and there are no permanent epidemics.
"It's a somewhat subjective assessment because it's not just about the number of cases. It's about severity and impact," said Dr. Michael Ryan, WHO's head of emergencies.
America's top infectious disease expert, Dr. Anthony Fauci, said this Sunday that covid-19 cannot be considered endemic until it drops to a "level that does not disrupt society."
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