The Atlanta Journal-Constitution
Omicron variant may fend off delta, study finds
Findings could suggest a less dire future for the pandemic if confirmed.
People who have recovered from an infection with the new omicron coronavirus variant may be able to fend off later infections from the delta variant, according to a new laboratory study carried out by South African scientists.
If further experiments confirm these findings, they could suggest a less dire future for the pandemic. In the short term, omicron is expected to create a surge of cases that will put a massive strain on economies and health care systems around the world. But in the longer term, the new research suggests that an omicron-dominated world might experience fewer hospitalizations and deaths than one in which delta continues to rage.
“Omicron is likely to push delta out,” said Alex Sigal, a virus expert at the Africa Health Research Institute in Durban, South Africa, who led the new study. “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.”
He posted the new study on the institute’s website Monday. It has not yet been published in a scientific journal.
Independent scientists said that the results of the South African experiment, although preliminary, were sound. Carl Pearson, a public health researcher at the London School of Hygiene & Tropical Medicine, said the findings were consistent with what is now happening in England.
“Omicron arrives and grows rapidly, and the delta trend switches to declining,” he said.
And Nathan Grubaugh, a public health researcher at the Yale School of Public Health, said he was observing the same pattern in Connecticut. “We are seeing omicron exponentially rise while delta cases are falling,” he said. “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.”
When people began getting infected with the coronavirus two years ago, they produced antibodies and immune cells that could provide protection against it. As a result, it was rare for a person to be reinfected in the months that followed.
But starting in late 2020, new coronavirus variants emerged. Some of them, like alpha, had mutations enabling them to spread rapidly. Others, like beta, had adaptations that allowed them to evade antibodies — whether they were produced during a prior infection or in response to a COVID-19 vaccine.
Delta, which came to prominence this past summer, had mutations that gave it a superior ability to spread and a moderate ability to evade antibodies. Vaccines still remained effective against delta, but not quite as much as they had been earlier in the pandemic.
When omicron emerged in November, it spread faster than delta had. Researchers suspected that its speed had two sources. Somehow it was able to transmit quickly — perhaps by replicating in large numbers or by spreading more easily from one person to the next. Omicron was also able to infect vaccinated people and those who had gotten sick with earlier variants.
In an earlier study in December, Sigal’s team, as well as a number of other research groups, confirmed omicron’s ability to dodge antibodies from vaccines and earlier variants. To do so, they analyzed blood from people who were either vaccinated or had recovered from COVID19, and mixed it with different variants.
Time and again, antibodies that were potent against delta and other variants did a poor job against omicron. This helped to explain why so many vaccinated and previously infected people were coming down with bouts of omicron, albeit milder than delta infections.
In their new study, Sigal and his colleagues ran the same experiment, but this time on people who had recovered from omicron infections. Although South Africa has just gone through a huge spike in omicron cases, Sigal and his colleagues have only been able to study 13 patients.
“This was very difficult because of the holiday period,” he said. “Nobody really wants to stick around and be part of a study.”
Seven of the patients were vaccinated, and six were not. The scientists did not determine which volunteers had been previously infected with other variants of COVID-19. But given that the vast majority of South Africans had COVID-19 before omicron, it’s likely that most of the volunteers had not been infected for the first time with omicron.
The researchers found, unsurprisingly, that the patients’ blood contained a high level of antibodies potent against omicron. But those antibodies proved effective against delta, too.