Analysis: How Omicron highlights fading hope of herd immunity from COVID

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CHICAGO, Jan 20 (Reuters) – The Omicron variant, which is spreading far sooner than earlier variations of the coronavirus, shouldn’t be probably to assist nations obtain so-called herd immunity in opposition to COVID-19, during which sufficient individuals grow to be proof against the virus that it will possibly now not unfold, main illness specialists say.

From the earliest days of the pandemic, public well being officers have expressed hope that it was doable to attain herd immunity in opposition to COVID-19, so long as a excessive sufficient share of the inhabitants was vaccinated or contaminated with the virus.

These hopes dimmed because the coronavirus mutated into new variants in fast succession over the previous yr, enabling it to reinfect individuals who have been vaccinated or had beforehand contracted COVID-19.

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Some well being officers have revived the potential of herd immunity since Omicron emerged late final yr.

The truth that the variant spreads so rapidly and causes milder sickness would possibly quickly expose sufficient individuals, in a much less dangerous method, to the SARS-COV-2 virus and supply that safety, they argue.

Illness specialists word, nevertheless, that Omicron’s transmissibility is aided by the truth that this variant is even higher than its predecessors at infecting individuals who have been vaccinated or had a previous an infection. That provides to proof that the coronavirus will proceed to search out methods to interrupt by our immune defenses, they stated.

“Reaching a theoretical threshold past which transmission will stop might be unrealistic given the expertise we’ve got had within the pandemic,” Dr. Olivier le Polain, an epidemiologist with the World Well being Group (WHO), informed Reuters.

That’s not to say that prior immunity presents no profit. As an alternative of herd immunity, many specialists interviewed by Reuters stated there was rising proof that vaccines and prior an infection would assist enhance inhabitants immunity in opposition to COVID-19, which makes the illness much less severe for individuals who are contaminated, or grow to be reinfected.

“So long as inhabitants immunity holds with this variant and future variants, we’ll be lucky and the illness will probably be manageable,” stated Dr. David Heymann, a professor of infectious illness epidemiology on the London College of Hygiene and Tropical Drugs.

NOT LIKE MEASLES

Present COVID-19 vaccines have been primarily designed to forestall extreme illness and loss of life fairly than an infection. However medical trial ends in late 2020 exhibiting that two of the vaccines had greater than 90% efficacy in opposition to the illness initially sparked hope that the virus may very well be largely contained by widespread vaccination, much like the way in which measles has been curbed by inoculation.

Check tube labelled “COVID-19 Omicron variant take a look at constructive” is seen on this illustration image taken January 15, 2022. REUTERS/Dado Ruvic/Illustration

With SARS-CoV-2, two elements have since undermined that image, stated Marc Lipsitch, an epidemiologist at Harvard T.H. Chan College of Public Well being.

“The primary is that immunity, particularly to an infection, which is the vital sort of immunity, wanes fairly rapidly, at the least from the vaccines that we’ve got proper now,” he stated.

The second is that the virus can rapidly mutate in a method that allows it to elude safety from vaccination or prior an infection – even when immunity has not waned.

“It modifications the sport when vaccinated individuals can nonetheless shed virus and infect different individuals,” stated Dr. David Wohl, an infectious illness specialist on the College of North Carolina at Chapel Hill College of Drugs.

He cautioned in opposition to assuming that an infection with Omicron would enhance safety, particularly in opposition to the subsequent variant which may come up. “Simply since you had Omicron, perhaps that protects you from getting Omicron once more, perhaps,” Wohl stated.

Vaccines in improvement that present immunity in opposition to future variants and even a number of sorts of coronaviruses might change that, stated Pasi Penttinen, the highest influenza professional on the European Centre for Illness Prevention and Management, however it would take time.

Nonetheless, the hope for herd immunity as a ticket again to regular life is difficult to shake.

“These items have been within the media: ‘We’ll attain herd immunity when 60% of the inhabitants are vaccinated.’ It did not occur. Then for 80%. Once more, it did not occur,” Francois Balloux, professor of computational techniques biology at College School London, informed Reuters.

“As horrible because it sounds, I believe we’ve got to arrange ourselves to the truth that the overwhelming majority, primarily everybody, will get uncovered to SARS-CoV-2,” he stated.

International well being specialists anticipate that the coronavirus will finally grow to be endemic, circulating persistently within the inhabitants and inflicting sporadic surges. The emergence of Omicron, nevertheless, has raised questions on precisely when which may occur.

“We are going to get there,” stated the WHO’s le Polain, “however we aren’t there in the mean time.”

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Reporting by Julie Steenhuysen; Further reporting by Emma Farge in Geneva, Alistair Smout in London and Francesco Guarascio in Brussels; Modifying by Michele Gershberg and Invoice Berkrot

Our Requirements: The Thomson Reuters Belief Ideas.

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