Less Severe Omicron Might Help Shield Against Deadly Delta

Less Severe Omicron Might Help Shield Against Deadly DeltaBy Cara Murez HealthDay Reporter
THURSDAY, Dec. 30, 2021

Researchers are still trying to figure out what will happen with both the Delta and Omicron variants of COVID-19 spreading simultaneously.

Now new lab-based data is suggesting that the newer variant, Omicron, might bring one silver lining: It could help folks who contract it defend against the prior variant, Delta.

Scientists in South Africa found that people who have recovered from an infection with Omicron produced antibodies that protected them against Delta. The reverse did not appear to be true, however.

Because Omicron appears to produce less severe illness than Delta, its overall effect might end up having a positive side, scientists said. While the Omicron variant is expected to strain health care systems and economies because if its extremely rapid spread, in the longer term -- if it continues to dominate -- there could be fewer hospitalizations and deaths than if Delta was to continue to lead.

"Omicron is likely to push Delta out," study lead author Alex Sigal told the New York Times. He's a virologist at the Africa Health Research Institute in Durban, South Africa. "Maybe pushing Delta out is actually a good thing, and we're looking at something we can live with more easily and that will disrupt us less than the previous variants."

The study was posted Monday on the institute's website. It has not yet been published in a scientific journal and has yet to undergo peer review, the newspaper reported.

The Delta variant became prominent last summer with mutations that made it spread more easily than earlier variants. It was also moderately able to evade immune-system antibodies, including those produced by vaccines.

Omicron emerged in November, experts believe. It spreads even more quickly than Delta and can infect people who've experienced a previous COVID infection and/or have been vaccinated, though it tends to spur milder cases of illness. The latest data from the U.S. Centers for Disease Control and Prevention estimates that 59% of current U.S. cases of COVID-19 are caused by the Omicron variant.

Earlier studies, using blood from people who were vaccinated or had recovered from cases of COVID-19, confirmed that antibodies derived from a prior Delta infection offered little protection against Omicron.

But Sigal believes that as people contract Omicron, they may gain some immunity to both that variant and Delta.

If that's true, then Delta will gradually have fewer people it can successfully infect, leaving Omicron to outcompete it. While scientists aren't sure why Omicron might provide immunity against the Delta variant, it's possible that Omicron may do the same other variants, as well.

The study included blood drawn from only 13 volunteers, but independent scientists called it sound, according to the Times. The volunteers were a mix of vaccinated and unvaccinated people, and Sigal's group tested the activity of the Delta and Omicron variants in the blood samples.

Two experts who spoke to the newspaper said the South African findings are consistent with patterns of current spread of SARS-CoV-2 being observed in England and in Connecticut.

“Omicron arrives and grows rapidly, and the Delta trend switches to declining,” said Carl Pearson, a British epidemiologist at the London School of Hygiene & Tropical Medicine.

Meanwhile, across the Atlantic, “we are seeing Omicron exponentially rise while Delta cases are falling," added Nathan Grubaugh, an epidemiologist at the Yale School of Public Health. "This suggests to me that Omicron is outcompeting Delta for susceptible individuals, leaving them less susceptible to Delta in the aftermath, and driving down Delta cases."

It's also possible that Omicron stimulated the volunteers' existing immunity from earlier infection or vaccination, the experts said. What it might do in unvaccinated people is still not entirely known.

Of course, Omicron's potential for dominating Delta doesn't mean that variants that can evade immunity won't arise again in the future.

There are still many unknowns. Speaking with the Times, Pearson offered three suggestions as to what could happen with the novel coronavirus going forward.

Every year there could be a different seasonal variant, similar to what happens with the flu, he said. Or several variants could coexist, evading different antibodies, similar to what happens now with Dengue fever, where people get sick every few years from one variant. Or -- in a best-case scenario -- one variant could dominate and make the virus much easier to manage, although Pearson believes this is least likely.

"I'd bet we can rule out that it's trending to a place where it locks into a single variety that's long-term immunizing and becomes a childhood infection like measles," he said. "But that's also still possible."

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19.

SOURCE: New York Times

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