Good news re Omicron

[Tryingtryingandtrying]

twitter.com/sailorrooscout/status/1468985784338366468?t=0RA5_V7CWbGjhgxfNIDbAQ&s=19

All looking pretty positive.

Bumping too. Love a positive thread!

I'm boosted as are all in my family eligible for it. But the kids aren't vaccinated. Milder makes me happy

bump for the good news

off to have my booster next week

Any info on twitter must be true

That entirely depends on who’s posting on Twitter.

Very good news. We're boosted but teenage grandchildren still only the one vaccine. Hopefully a second one will be offered to them at some stage.

www.mumsnet.com/Talk/coronavirus/4416171-Omicron-New-Variant-Thread-2-title-edited-by-MNHQ-at-OPs-request?pg=1
Hopefully some of the posters on the above thread will pop in and read the good news!

Oh look, here's a site just for Covid good news stories:

justgivemepositivenews.com/

Yep :) I wonder how quickly we can drop Plan B

I'm not sure what you think that thread means, @JanglyBeads?

Her first tweet:
A sketch to explain how a new variant may appear milder even with no change in underlying virulence.

The sketches are explaining why. What she is saying is that is that even if a smaller percentage of people become severely ill with omicron, you can't conclude that means it is less virulent than other variants.

Say you have 1000 people exposed to delta. If 500 of them have already had alpha and that stops them being reinfected with delta, only 500 people will be infected with delta.

Of the 500 hundred who are infected:
100 will get severe symptoms
200 will get moderate symptoms
200 with mild symptoms

So 20% (100/500 x 100%) of people infected with delta get severe symptoms.

Now say, you have 1000 people exposed to omicron. Again, 500 of them have had alpha. This time all 1000 people become infected because omicron is better at reinfecting people.

If omicron has the same virulence as delta.

Of the 500 hundred who are infected and have never had the virus before, so they have no immunity:
100 will get severe symptoms
200 will get moderate symptoms
200 with mild symptoms

Of the 500 who had alpha and therefore have some immunity to omicron:
0 will get severe symptoms
0 have moderate symptoms
500 have mild symptoms

So only 10% (100/1000 x 100%) of people infected get severe symptoms. It's not because omicron is less virulent, it's because people with immunity are being reinfected who wouldn't have been reinfected by delta.

Those are totally made up numbers just to explain what her sketches are showing. I'm not sure why she chose to have 0 reinfections in her first example but you can see the principle.

Her last tweet in the thread after explaining her first tweet:
So when I look at data out of South Africa or elsewhere, I am thinking not just about the proportion of cases that are severe, but also the sheer number of severe cases, which demonstrates the public health impact of the variant.

She's making the point that it isn't only the percentage of people who get severe symptoms that can have a serious public health impact, the number of severe cases is an issue. 10% of 10,000 is a lot less than 10% of 1 million.

Furthermore, although she doesn't actually state it, if you have 1000 people exposed to an infectious person but only 500 (50%) become infected, then each of those people infect 50% of their contacts (let's say each peson has 10 contacts. You go from 500 cases to 2500 to 12,500.

If you have 1000 people exposed to an infectious person and all 1000 (100%) become infected, then each of those people infect 100% of their 10 contacts, you go from 1000 cases to 10,000 to 100,000.

20% of 2500 is a lot less than 10% of 100,000.

I think we’re both making the same point @cheshirecat!

Are there any articles linked to read? I don't have twitter

I don’t think you need Twitter to read Twitter.

I'm not sure we are, @JanglyBeads.

And this sketch shows why less virulent but causing more reinfections matters

She is saying

a smaller percentage of severe cases does not mean less virulent

because

same virulence + more reinfections = a smaller percentage of severe cases

But sorry if we are!

I’m now confused, but we are definitely both saying that the apparently good news re omicron does not stand up to basic scrutiny, yes?

I think it was John Burn-Murdoch who made a point on twitter earlier today about clarifying what WHO say about it being milder.

No. Thats not strictly true and the statement is somewhat misleading. What is being observed is vaccines and previous immunity from infection are meaning its presenting as milder.

If you have someone who is unvaxxed (including children this time around) thats not necessarily true.

So this begs a few questions (certainly there are some places there could still be problems) and does encourage boosters.

Also re there seeming to be a bend in the curve suggesting cases are peaking - it has been pointed out this could merely be an issue with testing capacity as the positivity rate still appears to be rising - something that suggests there are more cases going unrecorded.

Whilst the news is definitely good and encouraging its does need pointing out potential flaws / remaining issues that the data reveals / is a significant omission.

Thats not about doommongering. This is about ensuring we are correctly assessing the info we have before rushing off cheering prematurely.

How on earth is there enough data yet

RTB, iirc the uptake of the vaccine in SA is quite low but their hospitalisations are still considerably lower than what they were at this stage with delta. It’s thought that previous infection is helping with that. With our higher levels of vaccination/immunity after infection we may actually be in a very good position for it to present much milder here as well.

Well, it's still good news that the percentage of severe cases is lower, whether that is because omicron is less virulent or due to high levels of immunity. It would be a whole lot worse if that weren't the case.

The transmission rate is bad news as health services could be overwhelmed by case numbers. I suppose high case numbers is not great news for the mutation rate either. Pi may be along sooner than expected.

@chesirecat99 why would they be overwhelmed by case numbers if it turns out to be mild and not result in as many hospitalisations?

The average age in South Africa is only a bit younger than Brazil or India (South Africa is not Niger--it's a middle income country). When Delta took hold in Brazil and India, we started seeing bad outcomes and car crashed hospitals pretty much straight away. It "feels" very different this time. I think that if Omicron was going to cause massive issues, we'd be seeing signs of it by now.

OMG, Christina Pagel has tweeted something optimistic.
Pigs are flying and the Pope has just converted to protestantism.

Because high transmission means a high number of cases at the same time, @bumbleymummy.

So if 1% of people have severe symptoms and you have 10,000 cases in a week, you have 100 people who need care in an ICU. They'll probably need to stay for several weeks, so the next week you have 200 people in ICU.

If 5% of people have severe symptoms but you only have 1000 cases in a week, you only have 50 people in ICU. Then the next week 100 people.

But even a high number of cases will mean little if only a tiny fraction have severe symptoms. Things from SA look promising so far.

@bumbleymummy

But even a high number of cases will mean little if only a tiny fraction have severe symptoms. Things from SA look promising so far.

As Cheshire has said twice, if it’s more virulent it will reach more people more quickly.

So say (and these are theoretical figures for example) it affected 2 in every 100 people severely, instead of 5 in every 100 people severely then that’s good.

But if it spreads five times more quickly it infects 500 people in the time the last variant infected 100. This would see 10 people (5x2) with severe disease instead of 5 (5x0) with the old variant.

So a more infectious variant can cause more severe disease more quickly due to its infectiousness. It can cause more breakthrough severe illness too. I had breakthrough severe illness from delta. I wouldn’t wish it on anyone and it seems more breakthroughs will happen - especially in those jabbed twice or less.

@bumbleymummy

But even a high number of cases will mean little if only a tiny fraction have severe symptoms. Things from SA look promising so far.

No. Because a tiny percentage of a huge number is more than a larger percentage of a smaller number.

@ChilliGoat more virulent means more severe, not more transmissible.

I’m perfectly able to do the math, thanks. I’m pointing out that if it’s very very mild and only results in a fraction of a percent of serious cases then having a high number of cases would not be an issue.