Why the Omicron Offshoot BA.5 is a Big Deal

CNN | By Brenda Goodman

Once again, Covid-19 seems to be everywhere. If you feel caught off-guard, you aren't alone.

After the Omicron tidal wave washed over the United States in January and the smaller rise in cases in the spring caused by the BA.2 subvariant, it might have seemed like the coronavirus could be ignored for a while. After all, the US Centers for Disease Control and Prevention estimated in December that nearly all Americans had been vaccinated or have antibodies from a past infection. Surely all that immunity bought some breathing room.

But suddenly, many people who had recovered from Covid-19 as recently as March or April found themselves exhausted, coughing and staring at two red lines on a rapid test. How could this be happening again -- and so soon?

The culprit this time is yet another Omicron offshoot, BA.5. It has three key mutations in its spike protein that make it both better at infecting our cells and more adept at slipping past our immune defenses.

 

In just over two months, BA.5 outcompeted its predecessors to become the dominant cause of Covid-19 in the United States. Last week, this subvariant caused almost 2 out of every 3 new Covid-19 infections in this country, according to the latest data from the CDC.

Lab studies of antibodies from the blood of people who've been vaccinated or recovered from recent Covid-19 infections have looked at how well they stand up to BA.5, and this subvariant can outmaneuver them. So people who've had Covid as recently as winter or even spring may again be vulnerable to the virus.

 

"We do not know about the clinical severity of BA.4 and BA.5 in comparison to our other Omicron subvariants," CDC Director Dr. Rochelle Walensky said at a White House Covid-19 Response Team briefing Tuesday. "But we do know it to be more transmissible and more immune-evading. People with prior infection, even with BA.1 and BA.2, are likely still at risk for BA.4 or BA.5."

A 'full-on' wave

The result is that we're getting sick in droves. As Americans have switched to more rapid at-home tests, official case counts -- currently hovering around 110,000 new infections a day -- reflect just a fraction of the true disease burden

"We estimate that for every reported case there are 7 unreported," Ali Mokdad, professor of health metrics sciences at the University of Washington's Institute for Health Metrics and Evaluation, wrote in an email.

Other experts think the wave could be as much as 10 times higher than what's being reported now.

"We're looking at probably close to a million new cases a day," Dr. Peter Hotez said Monday on CNN. "This is a full-on BA.5 wave that we're experiencing this summer. It's actually looking worse in the Southern states, just like 2020, just like 2021," said Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Houston.

That puts us in the range of cases reported during the first Omicron wave, in January. Remember when it seemed like everyone everywhere got sick at the same time? That's the situation in the United States again.

It may not seem like a very big deal, because vaccines and better treatments have dramatically cut the risk of death from Covid-19. Still, about 300 to 350 people are dying on average each day from Covid-19, enough to fill a large passenger jet…

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