The Omicron variant may not necessarily be super-transmissible but may be taking over in some countries because of waning transmission of the Delta variant, a biostatistician who has been carefully monitoring the spread of coronavirus said Tuesday.
“You can actually look and see on the ground, how many people do [you] think one person’s infecting, one infected person is spreading to. And if you look at Omicron, that is perhaps three times faster than Delta. That is what’s coming up in South Africa,” said Trevor Bedford, an associate professor in the Vaccines and Infectious Disease Division with the Fred Hutchinson Cancer Center in Seattle.
“That doesn’t mean it’s three times as transmissible as Delta,” Bedford told Andy Slavitt, former President Biden senior adviser on Covid-19, on Slavitt’s podcast.
“What I think is mostly going on is that Delta had a decreasing fraction of people that it was able to infect — where it was kind of people who were not vaccinated who are not infected, or people who’ve had enough waning immunity that they’re now available again to the virus,” Bedford added. “Whereas Omicron, by having such a different spike protein, has this whole susceptible pool of people available to it, so it can infect three times as many people.”
In other words, Delta has begun running out of people to infect, while few people have enough immunity to withstand Omicron. “It’s mostly about this immune escape difference that it has,” Bedford said.
Bedford said it is not a foregone conclusion that Omicron will eventually overtake Delta as the dominant variant in the US. The virus could behave more like the flu virus, where multiple lineages circulate at the same time.
“It’s possible, but not definite that that’s what we’d see with Omicron versus Delta-like viruses, that it won’t be that Omicron displaces Delta. It’ll be that in two years’ time. They’ll both be kind of continuing to coexist because they’re different enough,” he said.
“It also could be that they’re not quite different enough and that we still see like a wave and then Delta eventually displaces Omicron or Omicron displaces Delta. We don’t know yet. But those are the three scenarios — either only Delta, only Omicron, or both coexisting in two years’ time.”
