CDC: New virus variant appears to evade vaccines

As Omicron variants of the coronavirus continue to evolve, one strain called XBB.1.5 appears to evade vaccines and past infections and has grown at a fast pace in the US, doubling its infection numbers every week for the last four weeks, according to the US Centers for Disease Control and Prevention (CDC).

CDC data showed that between Dec 25 and 31 of 2022, XBB.1.5 accounted for more than 40 percent of all new COVID-19 cases. It has been spreading especially fast in the Northeast, where the variant accounted for about 75 percent of all new infections.

CNN reported that Dr David Ho, a professor of microbiology and immunology at Columbia University, found in his lab that XBB.1 was the most slippery of all subvariants. It was 63 times less likely to be neutralized by antibodies in the blood of infected and vaccinated people than BA.2, and 49 times less likely to be neutralized compared with BA.4 and BA.5.

That means the XBB.1.5 strain easily evades antibodies from prior infection, vaccines and existing monoclonal antibody treatments.

Ho said these levels of immune evasion are "alarming" and they could further compromise the efficacy of the COVID-19 vaccines.

In addition, XBB.1.5 has proved to be highly contagious. The new variant has a key mutation that allows it to bind more tightly to ACE2, the hooks the virus uses to enter cells.

Virologists and epidemiologists are concerned that the new Omicron sublineage could potentially drive a new surge of coronavirus cases in the US.

However, some experts say it's hard to know how much of XBB.1.5's growth can be attributed to properties of the virus and how much to the holiday timing when people were more likely to travel and gather, thus giving the virus more opportunities to infect people.

Some experts expressed optimism when looking at the situation in Northeast.

Michael Osterholm, director at Center for Infectious Disease Research and Policy at the University of Minnesota, told CNN that updated boosters should provide some protection.

"They still provide a level of immunity that may not prevent you from getting infected but may have a significant impact on whether or not you become seriously ill and die," he told CNN. "I mean, right now, the most recent data we have shown that for those who have the bivalent vaccine, they have a threefold lower risk of dying than those who don't."

Dr Jay Varma, an epidemiologist and director of the Cornell Center for Pandemic Prevention and Response, told PBS that while the XBB.1.5 variant is going to cause some ups and downs, "it doesn't appear that it's going to increase their risk of hospitalization and death beyond what has already happened in the past before".

Experts also pointed out that although antibody treatments aren't working against XBB.1.5, antivirals such as Paxlovid and remdesivir are still effective.