Those two variants spread more easily (more fusogenic) and cause greater pathology. Interesting to see that word but it means what it looks like it means. These variants are better able to latch on and invade mammalian cells.https://www.biorxiv.org/content/10.1101/2022.05.26.493539v1
After the global spread of SARS-CoV-2 Omicron BA.2 lineage, some BA.2-related variants that acquire mutations in the L452 residue of spike protein, such as BA.2.9.1 and BA.2.13 (L452M), BA.2.12.1 (L452Q), and BA.2.11, BA.4 and BA.5 (L452R), emerged in multiple countries.**** They reproduce better:
Our statistical analysis showed that the effective reproduction numbers of these L452R/M/Q-bearing BA.2-related Omicron variants are greater than that of the original BA.2. **** You are not protected by having had an omicron infection already:
Neutralization experiments revealed that the immunity induced by BA.1 and BA.2 infections is less effective against BA.4/5.
**** They attach to epithelial cells in the alveoli (the basic functional unit of the lung) and reproduce at a higher rate
Cell culture experiments showed that BA.2.12.1 and BA.4/5 replicate more efficiently in human alveolar epithelial cells than BA.2, and particularly, BA.4/5 is more fusogenic than BA.2.
**** In the hamster model that has been used now for the past 2 years (and now provides ample data for comparison to the wild-type SARs-CoV-2 and earlier variants) these two variants hit harder and make infected animals sicker.
Furthermore, infection experiments using hamsters indicated that BA.4/5 is more pathogenic than BA.2.------------------------
Altogether, our multiscale investigations suggest that the risk of L452R/M/Q-bearing BA.2-related Omicron variants, particularly BA.4 and BA.5, to global health is potentially greater than that of original BA.2.
From June 3rd
These subvariants are quickly gaining steam in the U.S.https://www.prevention.com/health/health-conditions/a40179304/omicron-ba-4-ba-5-new-variants-covid-19/
The vaccinated population may be more susceptible to BA.4/5 infections. Here's a quote from this news report.
https://deadline.com/2022/05/omicron-ba-4-ba-5-variants-increase-1235035960/"We now report findings from a systematic antigenic analysis of these surging Omicron subvariants,” says a recent paper published to the BioRxiv preprint server. “BA.2.12.1 is only modestly (1.8-fold) more resistant to sera from vaccinated and boosted individuals than BA.2. On the other hand, BA.4/5 is substantially (4.2-fold) more resistant and thus more likely to lead to vaccine breakthrough infections.”
This that study. Manuscripts published on biorxiv.org aren't peer-reviewed yet but getting the information out faster has been more common these past 2 years.
Igor Chudov's bio says "I own a popular math website and run a business." so take that for what you will but he is reporting on published data.
Portugal's daily new case count **per million people** is around 2500 (7-day rolling average) this past week while SA's 7-day average had a little blip over 100 and has now gone way down into the lower two-digit range.
It's a similar pattern to the 7-day daily new death rates. Portugal has what looks like a 4-fold higher death rate. Looking at the Y-axis might make it seem like 3.5 compared to less than 1 - big deal, right? But that graph is also showing the rate per million people, not the raw count.
From his substack:Summary: The BA4/5 sister variants currently dominate two countries: South Africa and Portugal.
South Africa is barely vaccinated (only 35% had a vaccine, 5% had a booster), whereas Portugal is 95% vaccinated and 70% boosted.
The situations in these countries could not be any more different: while Ba.4 and Ba.5 were mere blips on the radar in South Africa, these same variants are driving a deadly wave of Covid in highly-vaccinated Portugal, with deaths among the Portuguese nearing January peak and showing few signs of abating.
South Africa and Portugal form a two-country controlled experiment: vaccinate one country and do not vaccinate another, and expose both to Covid Ba4/5. The difference in outcomes is telling.-----------------------
It looks different on Worldometer where the graphs show the raw numbers reported by the country, state/province, and/or county.South Africa (population of 60.8M) shows 1600-2000 daily new cases (7-day average) and 25-30 (7-day average) daily new deaths.South Africa had 4 obvious waves over the course of the pandemic but looks like they have not been affected much at all in comparison by this spring's BA.4/5 wave.
Portugal (population 10.2M) shows daily new cases in the 20000-25000 range (7-day average) but it looks like it is going down quickly (yay!), Their (7-day average) daily new deaths count is still increasing though. That rolling average has gone from 30 to just under 40 in the past week.
Those daily new case numbers due to omicron are huge compared to the winter of 2020-2021. The death rate now has thankfully stayed lower compared to that period.
Has there ever been a virus like this where infection could result in being asymptomatic at one end, and death at the other end, of the spectrum? The varying outcomes of infection are one of the main issues in how people view it. The broad range of outcomes from infection are truly a phenomenon imo.
the18thletter said:Has there ever been a virus like this where infection could result in being asymptomatic at one end, and death at the other end, of the spectrum? The varying outcomes of infection are one of the main issues in how people view it. The broad range of outcomes from infection are truly a phenomenon imo.
Off hand, I cannot recall.
I am thinking that polio is a viral illness that can have almost no symptoms for most and does become a very severe illness for others. There was some news on NPR radio where this was briefly discussed. So, I will try and go to the CDC records and look for info on this. And chicken pox and herpes can cause very mild symptoms but become very severe later in life.
Per the CDC web site: 72 out of 100 polio infections have no symptoms.
added info : per CDC, one out of 100 polio infections results in serious illness.
My take on this number: This is not much different from covid. The next info look up is to see what percentage of childhood infections result in serious infections.
RobertRoe said:Per the CDC web site: 72 out of 100 polio infections have no symptoms. https://www.cdc.gov/polio/what-is-polio/index.htm
I've seen as high as 95% asymptomatic with polio. Polio is before my time but seems very similar to Covid in terms of outcomes. Thankfully polio didn't mutate as much a Cov2 does because it doesn't look like we'll be able to eradicate Cov2 through vaccination.
Peter, I’m sorry I haven’t kept up with your June posts; been trying to kick a supposedly ‘mild’ lower respiratory virus for most of the month, then landed up in ED with a disgusting migraine. (These hit about once every 4 years, different to my usual)
My discharging doc was saying this morning that the mix of respiratory viruses around this year has really rocked the Population Health community. Just ‘the flu’ would be bad enough (really mean mix), but also so many other viruses that rankle and set you up for original Omicron (we’re going through another surge). There’s even some dengue and Barmah fevers circulating out of season. (They’re mosquito borne)
The worst part of polio, even for patients who severe cases then learnt to live with disabilities, is the post-polio syndrome that arrives as forgotten ‘gift’ anytime from middle age. We used to say, a little like chicken pox brings adult shingles only much much worse and you don’t get over it. Truly hope covid doesn’t carry anything like this.
the18thletter said: I've seen as high as 95% asymptomatic with polio. Polio is before my time but seems very similar to Covid in terms of outcomes. Thankfully polio didn't mutate as much a Cov2 does because it doesn't look like we'll be able to eradicate Cov2 through vaccination.
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