The twists and turns of the variants never seem to end
Dominant coronavirus mutant contains ghost of pandemic past
The coronavirus mutant that is now dominant in the United States is a member of the omicron family but scientists say it spreads faster than its omicron predecessors, is adept at escaping immunity and might possibly cause more serious disease.
Why? Because it combines properties of both omicron and delta, the nation's dominant variant in the middle of last year.
A genetic trait that harkens back to the pandemic's past, known as a “delta mutation," appears to allow the virus "to escape pre-existing immunity from vaccination and prior infection, especially if you were infected in 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 ground in the U.S. — known as BA.2.12.1 and responsible for 58% of U.S. COVID-19 cases last week — isn't the only one affected by the delta mutation. The genetic change is also present in the omicron relatives that together dominate in South Africa, known as BA.4 and BA.5. Those have exactly the same mutation as delta, while BA.2.12.1 has one that's nearly identical.
This genetic change is bad news for people who caught the original omicron and thought that made them unlikely to get COVID-19 again soon. Although most people don't know for sure which variant caused their illness, the original omicron caused a giant wave of cases late last year and early this year.
Long said lab data suggests a prior infection with the original omicron is not very protective against reinfection with the new mutants, though the true risk of being reinfected no matter the variant is unique to every person and situation.
“The omicron infection antibody does not appear to protect well against the subvariants compared to delta,” said Dr. Shan-Lu Liu, a study author who co-directs the viruses and emerging pathogens program at Ohio State.
Scientists are still trying to figure out how virulent these new mutants are. Long said he hasn’t seen anything that answers that question for him, but Liu said emerging data points toward more serious illness. Liu said the subvariants have properties suggesting they spread more efficiently cell-to-cell.
The virus "just hides in the cell and spreads through cell-to-cell contact,” Liu said. “That's more scary because the virus does not come out for the antibody to work.”
Dr. Eric Topol, head of Scripps Research Translational Institute, said the new mutants certainly don’t appear less virulent than previous versions of omicron, and whether they are more virulent or not "will become clear in the months ahead.”
In the meantime, scientists expect the latest powerhouse mutants to spread quickly, since they are more transmissible than their predecessors.
“I’m hopeful that we don’t see a similar increase in hospitalizations that we’ve had in prior waves,” Long said. “But with COVID, any time you have lots of people being infected, it’s just a numbers game. Some of those people are going to be severe. Some of those people are going to need hospitalization. Some of them, unfortunately, are going to pass away.”
Some have been touting the “nature immunity” that is being provided by the Omicron variant, i.e., mostly mild cases that have replaced the more dangerous Delta variant. They see Omicron as accomplishing naturally what vaccination does.
ReplyDeleteUnfortunately, the cost of this natural immunity by mild infections has been that some people still get hospitalized with COVID, and then some die. Although it is only a small percentage of cases, those numbers add up because of the very high rates of infection by Omicron. Vaccination rarely sends people to the hospital.
The other cost of this natural immunity is that the huge number cases permit many more mutations. In this case, the new mutations have some of the characteristics of the Delta variant. Just because the Omicron variant has milder cases does not mean that its future variants will also have mainly mild cases.
Now that Michigan is releasing stats only once a week, and that so many home tests not rolled into health dept reports, it's very hard to get a bead on the local situation. Official infection stats went down 18 percent over the last week, but who knows what that means.
ReplyDeleteAnecdotally, we know many more people who have become sick with the latest mutation, mostly people who are working outside the home and/or have school page kids. The kids seem to be major transmitters.
I've been following hospitalization and death trends, which seem to be better indicators of severity vs incidence of the dominant mutation.
During the first waves of covid, the hospitalization rate was 20 percent of those infected. Now it's 10 percent. It may even be lower than that because incidence rates are likely higher than official numbers, again due to home testing.
To put that in perspective, about 2 percent of those infected with flu, even in a bad year, need hospitalization. (Check my math here https://www.cdc.gov/flu/about/burden/index.html )
I have been trying to get out once a week for socializing depending on local stats. Outdoor parks are my first choice. Coffee shops on weekdays, mid afternoons are good. I have been out for lunch twice since Delta subsided, both at 1:30 when crowds cleared out.
I stay out of theaters, churches, and other crowds indoors.
It is very difficult to compare the variants. They differ in how transmittable they are, and also what they infect (upper respiratory vs. lungs. That affects not only case numbers, but also hospitalizations and even deaths. With Omicron we have many patients in the hospital for other reasons who also have a slight case of Omicron. We also have people who are dying of other causes who also have mild cases of Omicron. Our reporting systems has to distinguish hospitalization with Covid from hospitalizations for Covid, and deaths due to Covid from deaths with Covid.
DeleteMost researchers agree that the best estimate of the impact of Covid is excess deaths, i.e., the number of deaths per year now in comparison with what they were before the pandemic. A recent WHO study revealed in many countries the excess deaths are far higher than the deaths attributed to Covid. In the US the excess deaths are only slightly greater than the reported deaths. Of course, excess deaths also include many who did not have treatments for other diseases because of Covid.
*Sigh*. Coronavirus , the gift that just keeps on giving. I'm contemplating when and if to get my second Moderna booster. From what I'm reading, the second booster is a case of diminishing returns. I got the first booster last fall. I lost a bunch of hair in late fall and early winter, now I'm finally getting some of it back. I know, correlation isn't causation. My hairdresser lady said stress can cause hair loss, and 2021 was full of stress of one sort and another. Probably will consult my doctor about the second booster.
ReplyDeleteGlad your hair us growing back. It sure makes you wonder, eh? I had my second booster in March, but these things seem to peter out after four or five months. I read that Pfizer and Moderna are looking at developing a new vax for the mutant strains, but whether they can keep up with them remains to be seen.
DeleteI got my 2nd boost last month. I went with Pfizer after getting Moderna for previous vaccinations. Nothing to report on my end - no I'll effects or any effects at all. I am getting COVID tested on Sunday, preparatory for some outpatient treatment (elective, routine stuff) in a few days. So we'll see.
ReplyDeleteOne of the ladies I know from dance just contracted it. 100.5°F fever and lots of coughing. Her husband is still not positive and he's due to start chemo. I just sent a text to see how they're doing.
ReplyDeleteGood luck and prayers for Jim for his outpatient treatment to go successfully. And prayers for Stanley's friend to recover quickly, and that her husband doesn't catch it.
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