The coronavirus mutant that is currently dominant in the United States is a member of the omicron family, but scientists say it spreads faster than its omicron predecessors and is adept at escaping immunity.
Why? Because it combines the properties of omicron and delta, the country’s dominant variant in the middle of last year.
A genetic trait reminiscent of the pandemic’s past, known as the ‘delta mutation’, appears to allow the virus ‘to escape pre-existing immunity from vaccination and previous infection, especially if you have been infected by the omicron wave,” said Dr. Wesley Long, a pathologist at Houston Methodist in Texas, that’s because the original omicron strain that swept the world didn’t have the mutation.
The omicron “subvariant” gaining traction in the United States – known as BA.2.12.1 and responsible for 62% of COVID-19 cases in the United States last week – is not the only affected by the delta mutation. The genetic change is also present in the relatives of the omicron which together dominate in South Africa and are gaining ground in the United States – BA.4 and BA.5. These have the exact same mutation as delta, while BA.2.12.1 has one that is nearly identical.
This genetic change is bad news for people who caught the original omicron and thought it made them unlikely to get COVID-19 again soon. Although most people aren’t sure which variant caused their illness, the original omicron caused a giant surge of cases late last year and early this year.
Long lab data suggests that prior infection with the original omicron is not very protective against reinfection with the new mutants, although the true risk of being reinfected, regardless of variant, is unique to each person and each situation.
Data from Chicago showed that last week reinfections accounted for about 10% of new COVID cases, an increase from recent months, although health officials said many of the recent reinfections were among residents who had contracted COVID some time ago, before the omicron wave.
In a twist, however, those who were already Delta-sick can have additional armor to ward off New Mutants. A study published before being reviewed by other scientists, by researchers at Ohio State University, found that COVID patients in intensive care with delta infections induced antibodies that neutralized new mutants better than patients who had caught the original omicron.
“The omicron infection antibody does not appear to protect well against subvariants compared to delta,” said study author Dr. Shan-Lu Liu, who co-leads the virus and pathogen program. emerging in the state of Ohio.
But Liu said the level of protection provided by a delta infection depends in part on how long a person has been sick. This is because immunity wanes over time.
People who have become delta-ill should not consider themselves invulnerable to the new subvariants, especially if they are not vaccinated, Long said. “I wouldn’t say anyone is safe.”
A bright spot? Booster shots can provide strong protection against new mutants, Liu said. In general, vaccines and previous infections can protect people from the worst consequences of COVID-19. At this point, scientists say, it’s too early to know if the new mutant gaining traction in the United States will lead to a significant increase in new cases, hospitalizations and deaths.
Scientists are still trying to determine the virulence of these new mutants. Long said he hasn’t seen anything that answers that question for him, but Liu said emerging data points to more severe disease. Liu said the subvariants have properties suggesting they spread more efficiently from cell to cell.
The virus “simply hides in the cell and spreads through cell-to-cell contact,” Liu said. “It’s scarier because the virus doesn’t come out for the antibody to work.”
Dr. Eric Topol, director of the Scripps Research Translational Institute, said the new mutants certainly don’t seem less virulent than previous versions of omicron, and whether or not they are more virulent “will become clear in the coming months.” .
Chicago’s top doctor said the city is watching for new variants, especially BA.4 and BA.5.
“Nothing about BA.4, BA.5 at the moment makes me worry that it is likely to see a significant increase, but it continues to show us that the virus is continuing to evolve,” the department commissioner said. of Chicago Public Health, Dr. Allison Arwady. Tuesday.
She added that the city “doesn’t see that it’s making people more seriously ill or showing up in different ways.”
In the meantime, scientists expect the latest potent mutants to spread rapidly, as they are more transmissible than their predecessors.
“Hopefully we don’t see a similar increase in hospitalizations that we’ve had in previous waves,” Long said. “But with COVID, anytime you have a lot of infected people, it’s just a numbers game. Some of these people are going to be tough. Some of these people will have to be hospitalized. Some of them, unfortunately, will die.