SARS-CoV- 2 variants

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Winston

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First, an example of marketing bologna:

Pfizer Covid vaccine 'is 100% effective against South African variant, beats Brazilian strain' AND works for at least six months - while lower antibody levels seen in lab tests do NOT affect jab's real-world protection - 1 Apr 2021


On the contrary:

Pfizer/BioNTech, Dose 2 + 6-Month Follow-Up Results


Now to the right-hand panel. The trial has a South Africa arm (well, at 800 participants, more like a “finger”). Of these, 9 placebo-group participants became infected, and zero vaccine group-participants. Of the 9 placebo-group participants, 6 were confirmed to have been infected by the B.1.351 lineage. If you have 6 placebo infections, and zero vaccine infections, you get the plot on the right hand side. This is what the flacks who work for Pfizer’s PR department have to say about this:

"In South Africa, where the B.1.351 lineage is prevalent and 800 participants were enrolled, nine cases of COVID-19 were observed, all in the placebo group, indicating vaccine efficacy of 100% (95% CI, [53.5, 100.0]). In an exploratory analysis, the nine strains were sequenced and six of the nine were confirmed to be of the B.1.351 lineage. These data support previous results from immunogenicity studies demonstrating that BNT162b2 induced a robust neutralizing antibody response to the B1.351 variant, and although lower than to the wild-type strain, it does not appear to affect the high observed efficacy against this variant."

OK, now look at that plot. Does that say “100% efficacy against B.1.351” to you? Because to me it says “we got bupkus for evidence, since we had too few people in South Africa participating in this study.” The 90% credible region starts at 50% efficacy!

You should also be aware that the stuff about “robust neutralizing antibody response” is based on this paper, which however showed that in-vitro neutralization of B.1.351 required far more concentrated vaccine-induced antibodies than were required for other variants — I cannot understand how the how one could possibly characterize that result as “robust”. In any event, its a wet lab result, not a clinical trial. We still don’t have any quality evidence about the performance of the mRNA vaccines against the B.1.351 variant. And that has me very worried.


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Excellent:

COVID-19 VACCINE EFFICACY PAGE


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US COVID-19 Cases Caused by Variants


The three variants tracked there:

Lineage B.1.1.7


Lineage B.1.1.7[a] is a variant of SARS-CoV-2, the virus that causes COVID-19. One of several variants believed to be of particular importance, it is estimated to be 40%–80% (with most estimates lying around the middle to higher end of this range) more transmissible than the wild-type SARS-CoV-2 and was detected in November 2020 from a sample taken in September, during the COVID-19 pandemic in the United Kingdom; it began to spread quickly by mid-December, and is correlated with a significant increase in SARS-CoV-2 infections in the country. This increase is thought to be at least partly because of one or more mutations in the virus's spike protein. The variant is also notable for having more mutations than normally seen.

Lineage B.1.351


The 501Y.V2 variant, also known as 20H/501Y.V2 (formerly 20C/501Y.V2), B.1.351 lineage and colloquially known as South African COVID-19 variant.

Researchers and officials reported that the prevalence of the variant was higher among young people with no underlying health conditions, and more frequently causes serious illness in such cases than other variants. The South African health department also indicated that the variant may be driving the second wave of the COVID-19 pandemic in the country, as the variant spreads faster than other earlier variants of the virus.

Lineage P.1



It caused widespread infection in early 2021 in the city of Manaus, capital of Amazonas, although the city had already experienced widespread infection in May 2020[9] with a study indicating high seroprevalence of antibodies for SARS-CoV-2. [meaning it bypassed natural immunity from previous infections - W] Early studies, not yet peer-reviewed, indicated as of March 2021 that P.1 infections can produce nearly 10 times more viral load than in other COVID-19-infected persons and showed 1.4–2.2 times higher transmissibility; were more successful infecting younger humans with no gender differential; can be 10–80% more lethal; are capable of evading 25–61% of immunity from previous coronavirus diseases, leading to the possibility of reinfection. At least some vaccines were found to be significantly less effective than against other variants.

Deadly variant [P1] fuels Brazil's COVID-19 crisis - 14 Apr 2021

 
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cwbullet

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Clearly, we are not out fo the woods.
 

Winston

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Clearly, we are not out fo the woods.
That's for sure. Canada, too. I just got done doing a rough investigation of what's going on there. My best hunch is that these spikes are being caused by new variants.

COVID-19 measures, updates, and guidance issued by Transport Canada


As of February 21, 2021 at 11:59 pm ET, you must meet the new testing and quarantine requirements when coming to Canada.

Canada's third wave on track to become its worst yet as hospitalizations spike
9 Apr 2021


(CNN) Canada's third wave of the pandemic is now more serious than the previous two, as hospitalizations and critical care admissions spike and the vaccine rollout is unlikely to change things over the next few weeks.

"The end is definitely in sight but we're not there yet. This third wave is more serious and we need to hang in there for another few weeks to make sure that we can flatten that curve, drop those numbers down again, to give a chance for vaccines to take hold," said Canadian Prime Minister Justin Trudeau during a press conference in Ottawa Friday.

The situation is most serious in Ontario, Canada's most populous province, where officials say the province is close to its 'worst case scenario' projections for the third wave. The province came dangerously close on Friday to shattering a record for a single day increase in cases and has already set a record this week for intensive care unit admissions related to Covid-19.

"We're seeing more and more young people being admitted to hospital with Covid-19. So to young people: There are more contagious and more serious variants out there, even if you're younger, you can get sick very, very quickly," Trudeau said.






Vaccination coverage comparisons:

Canada


U.S.


Generally better in the US, but Canada has a much higher percentage vaccinated for older people. So, I suspect their problem with a spike in cases may be caused by one or more of the newer variants which are more likely to affect the young although I haven't looked for the variant figures there. I'm going by Trudeau's comment and their recently (re)enacted testing and quarantine requirements for entry into the country. Unfortunately, for what's already there, it's obviously too late, although the death rate hasn't spiked nearly as much as their case figure.
 

Winston

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Looks like my hunch was right:

Covid-19 variants have likely replaced original virus in many parts of Canada, health officials say - April 6, 2021


Canadian public health officials say a rapidly spreading variant likely has now replaced the original Covid-19 virus in many parts of the country, and new variants are making younger people sicker and sending more to the hospital.

"This isn't the news any of us wanted, but hospitalizations are surging, ICU beds are filling up, variants are spreading and even people who had convinced themselves they didn't need to be concerned are getting sick," Canadian Prime Minister Justin Trudeau said at a news conference Tuesday, adding this is a "very serious" third wave of the pandemic.

Trudeau made a pointed appeal to young people, urging them to "stay home" as younger Canadians are getting sicker in this third wave.

Intensive care unit admissions are up 18% in the past week alone, and the new variants are placing a "heavy strain" on hospital capacity, the Public Health Agency of Canada said.

"With increasing rates of infection, we are seeing a greater number of younger adults with Covid-19 being treated in hospital," said Dr. Theresa Tam, Canada's chief public health officer. She added that more than 15,000 variant cases have been detected so far, the vast majority of them the B.1.1.7 variant first detected in the United Kingdom.
 
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