Yes, I very much hope that is the case. The information coming out is promising.
Crap. I asserted it after the data was available, and based on the data.
In fact, the reason that doctors in South Africa first suspected a new variant and sent samples for genetic sequencing was that they were seeing cases that were unexpectedly mild.
On Dec 13, I posted graphs showing that although the infection rate was high in SA, the death rate was low. Hospitalization reports showed that the hospitalization rate was low too, and holding steady.
The Discovery Health report of Dec 14, based on the data of over 200,000 patients, found that “Risk of severe disease and hospitalisation is significantly lower in Omicron infection compared to prior variants.”
On Dec 18, I linked to Prof. Shabir Mahdi, a top virology expert, saying that hospitalization was a third of Delta, and the case numbers were already on the way down in the first outbreak area.
The graphs I posted in post #260, showing lower hospitalizations and deaths across all age groups were from Dec 18.
Doctors in New York were reporting that omicron was far milder than delta on Dec 19, and the data from New York State and the UK was mirroring the SA experience by at least the same date.
Don’t accuse me of making a lucky guess because you were incapable of following and analyzing the data.
And the text above the graph in the article you link: “This shows that, adjusted for age, Omicron has far lower hospitalisation rates (perhaps due to vaccines).” (emphasis mine, the “s” is theirs.)
We all hope Omicron is milder, this isn’t some political thing where I’d rather suffer than be wrong. I’m giving the well respected scientific answer of “I don’t know.” I haven’t seen any convincing analysis. There are some trends suggesting it might be milder, but nothing so far has all of the pieces necessary to draw a conclusion. The reverse is also true, I’m not seeing things that suggest it is far more harmful of an infection.
What is needed to draw strong conclusions is data where both age and vaccination status are accounted for when comparing Omicron and non-Omicron variants.
Like all things COVID, we want answers now, but we just don’t have them yet. As data comes in (AKA, people get sick, go to the hospital, and die) we’ll get those answers.
There are now few countries that don’t have significantly vaccinated populations and/or a high rate of seropositivity for covid. So whether or not omicron is inherently milder for an unvaccinated person who has never been exposed to covid doesn’t make much practical difference to public policy.
For all practical purposes in the real world currently (and even more so in future), the effects of omicron are far milder than previous variants. The reasons why the effects are milder (whether vaccination/exposure or inherent mildness) may be of interest, but they are not going to change the conclusion that the overall effect on the population is milder, and they are not going to change the advice to get vaccinated and boosted.
The Discovery Health study of Dec 14 found that a two-dose vaccination with the Pfizer vaccine gave 70% protection against hospital admission, and that the level of protection was similar across all age groups. The anecdotal evidence is also that the great majority of people in hospital with omicron are unvaccinated, so vaccinations appear to have a significant protective effect.
Other anecdotal evidence I’m hearing here is that for most people who have symptomatic omicron illness (we don’t know how many asymptomatic cases there are), it’s like a bad cold that appears rapidly, lasts 2-3 days, and disappears just as rapidly.
We may be approaching a period of herd immunity where covid will subside to something like the level of seasonal flu. Prof. Karim noted:
“In South Africa, variants, even highly mutated ones, will run out of people pretty quickly,” he said. “Pretty much by the end of last week it was running out of steam; there just aren’t enough people left to infect.”
Imperial College, London Report 50 - Hospitalisation risk for Omicron cases in England is out (Dec 22)
You can download a PDF of the full report - link half way down page, on the right.
I’m not confident in analysing and presenting a summary of this sort of stat fest; but what I take from it is that the hospitalization risks from omicron are lower than the risks from delta across the board (with the usual caveats) - vaccinated, unvaccinated, prior infection, whatever.
Anyone care to do the job I just backed out of?
j
ETA - here’s a snippet:
Overall, we find evidence of a reduction in the risk of hospitalisation for Omicron relative to Delta infections, averaging over all cases in the study period. The extent of reduction is sensitive to the inclusion criteria used for cases and hospitalisation, being in the range 20-25% when using any attendance at hospital as the endpoint, and 40-45% when using hospitalisation lasting 1 day or longer or hospitalisations with the ECDS discharge field recorded as “admitted” as the endpoint (Table 1). These reductions must be balanced against the larger risk of infection with Omicron, due to the reduction in protection provided by both vaccination and natural infection.
I guess there’s still literally no data on the incidence of long covid from omicron…
Missed the edit. For those reading the Imperial report, a note on this paragraph:
Stratifying hospitalisation risk by vaccination state reveals a more complex overall picture, albeit consistent with the unstratified analysis. This showed an apparent difference between those who received AstraZenca (AZ) vaccine versus Pfizer or Moderna (PF/MD) for their primary series (doses 1 and 2). Hazard ratios for hospital attendance with Omicron for PF/MD are similar to those seen for Delta in those vaccination categories, while Omicron hazard ratios are generally lower than for Delta for the AZ vaccination categories. Given the limited samples sizes to date, we caution about over-interpreting these trends, but they are compatible with previous findings that while protection afforded against mild infection from AZ was substantially reduced with the emergency of Delta, protection against more severe outcomes was sustained (2,3). We emphasise that these are estimates which condition upon infection; net vaccine effectiveness against hospital attendance may not vary between the vaccines, given that PF/MD maintain higher effectiveness against symptomatic infection with Omicron than AZ (4).
The authors haven’t pointed out that initially the plan was to vaccinate everyone in the UK with AZ - then very rare but severe side effects were noted in younger patients, so they were reallocated to receive PF or MD. The authors discuss trends in terms of cohorts receiving different vaccines, but haven’t addressed the age differences between the two cohorts. My initial reading is that you could interpret this data as supporting the idea that the age-related bias of risk seen with delta is not being seen with omicron - with all the usual caveats applying etc etc.
j
The daily number is out for my state. There is a record new 15,482 cases in New Jersey. Hospitalizations are up slightly to 2,241. But the hospitalization number is down 1,632 from the peak last winter. Totals are up to record numbers but the rate of hospitalization is down.
I tried yesterday with the Scottish paper that I linked above, then deleted my post because I didn’t feel I had done a thorough enough job of looking properly at their methods, which would involve looking back at prior papers and understanding some statistical techniques that I have frankly never heard of. I’m not an epidemiologist, I have never even played one on TV. With that caveat, I’ll repost what I think that Scottish paper is saying. Here’s the link again.
They had almost 24,000 Omicron cases. They certainly did control for risk factors (vaccination status, age, etc.) using sophisticated methods. However, they only produced a single overall estimate of a two-thirds reduction in hospitalization vs Delta.
I think what’a going on is that they have enough data on Delta to give a null hypothesis expected number of hospitalizations in the Omicron cohort that takes into account differences in vaccination status, age etc. And the observed total number of hospitalizations (15) was two thirds lower. But the number of hospitalizations was too small to allow them to provide separate estimates for (say) vaccinated and unvaccinated Omicron infections.
I think these data are halfway to what we’d ideally want, and definitely very good news. They do control for vaccination status etc., but there is only enough statistical power to provide an overall estimate of hospitalization rate that is implicitly weighted according to the actual risk profile of the Omicron cohort.
Reading through this now. A big caveat from me:
I do not have the domain specific knowledge to know if their analyses are the best or even correct analyses to perform. That is what peer review by knowledgeable experts is all about.
A few points from the paper:
- “Hence simple division of numbers hospitalised by total cases for each variant gives a misleading impression of relative severity.”
- Fewer hospitalizations observed with Omicron, but
- Much greater reinfection rate with Omicron than Delta
- Some “first time” cases with Omicron are actually reinfections, because the first infection was never reported
- Vaccines, particularly AstraZeneca, have lost a lot of effectiveness at preventing disease with Omicron
- Vaccines, including AstraZeneca, retain effectiveness at preventing hospitalization
- Prior infection helps prevent hospitalization
- “The estimates in Table 3 suggest unvaccinated cases have somewhat lower risk of hospitalisation with Omicron versus Delta, though the magnitude of this reduction drops when under ascertainment of reinfections is accounted for.”
- Uncorrected for unknown reinfections, the hazard ratio of hospitalization for Omicron compared to Delta in unvaccinated is 0.59. You are 0.59 times as likely to be hospitalized with Omicron as you are with Delta.
- Correcting with an estimate that \frac{1}{3} of Omicron infections are actual reinfections, the hazard ratio in unvaccinated changes to 0.76.
- “The extent of reduction is sensitive to the inclusion criteria used for cases and hospitalisation […]” They get different answers if they change their parameters. This doesn’t necessarily mean they are wrong or right, just that different questions have different answers.
- Due to the newness of Omicron, determination of the most severe cases is not possible, because of no long-range followup (not enough time has passed)
- Commenting on the report from South Africa “an odds-ratio of 0.2 is not incompatible with the hazard ratios for protection from prior infection and vaccination”. Urgh, clunky sentence with double negative. They apparent lower danger seen with Omicron in South Africa is possibly due to higher reinfection rate and higher vaccination rate.
- And their caveats
- They assume Delta and Omicron get severe at the same speed.
- Omicron reports mostly come from large, inner-city hospitals, while Delta reports come from a more varied mix of hospitals, so some of the differences seen may be due to reporting differences between different hospitals types.
- Demographics of those infected differ between the strains. Omicron is younger and less white than Delta. They try to correct for this, but can’t be sure they’ve removed all bias.
- They didn’t have power to examine more severe outcomes than just showing up at a hospital.
- They’ll update as more data comes in—meaning when enough people die of Omicron to get a handle on that level of severity.
My over all impression, is that the paper reads like a first draft. For example, they say “… Omicron … Delta, respectively” and then in the next sentence say “… Delta … Omicron, respectively”. I mean, keep the order consistent. They don’t define Pillar 1 (hospital testing) and Pillar 2 (community surveillance testing) until the end of the discussion. I’m sure UK epidemiologists are familiar with the terms, but if you’re going to define it in the discussion, then define it the first time you mention it!
As I said at the top, I can’t comment on the appropriateness of their analyses, but they’re the pros, so I’ll give them the benefit of the doubt.
Bottom, bottom line, by me. At this moment, the severity of Omicron does not seem worse than Delta, and it may be milder even in naive unvaccinated people, but that is far from a hard fact, just the way things seem to be pointing now, very early in the Omicron wave.
Well, hats off for that summary. A fine job - thank you!
j
I had trouble with table 3 when trying to make this interpretation. If the people in row 16 vs row 3 are truly naive unvaccinated people, then there really is a 40% reduction in hospital risk. When they correct for underreporting, the reduction drops to 25%. Vaccines help a lot except mRNA greater than 21 days is no more protective than prior infection. Good thing that UK has been boosting like a bat outta hell.
So, if this burns itself out quickly like people are hoping is what is happening in SA, these data are good. If the surge goes on for more than a month, it seems to me that hospitals will be strained. Especially here in the US.
I think it’s very difficult to try to control perfectly for all confounding variables until you have so much data that it’s almost too late to matter. What gives me much greater confidence is that we’re at least starting to see a similar pattern in the U.K. to the pattern we saw in South Africa. The more data we see like this, the more confident we can be in saying - well, there may exist confounding variables, and we don’t have sufficient statistical power to untangle what they are, but in practice they don’t matter, because those variables apparently do not differ significantly between S.A. and other populations we’re interested in.
I think what worries me most at this point is the prospect of what may happen in Third World countries with very low vaccination rates and low seropositivity (if any such countries still exist) as Omicron sweeps through them incredibly fast. Or perhaps faster spread with lower mortality is better if you don’t have access to hospital care? I’m really not sure.
The real problem, and it’s not the fault of the authors, is that we still don’t have enough data. The confidence intervals are all over the place on some of the subcategories, simply due to small sample sizes. So in the uncorrected data, those infected with Omicron in the “Got the second dose of Pfizer/Moderna in the past 14 days” group were expected to have a 56% reduction in hospitalization. The problem is that 95% confidence interval for this group ranged from an 86% reduction to an 2% increase in hospitalizations. Hard to make good predictions from that.
Both that study and the one out of Scotland appear to have been well done (thanks again to @echoreply for the excellent summary of the Imperial College paper!), but both have been performed with one hand and two feet tied behind their backs. The results are promising, but if it turns out that it halves the serious hospitalization rates of Delta, but infects three times as many people, we’re still in trouble.
Yet another report – this one from the UK Health Security Agency:
Another factor to take into account is that, in addition to lower hospitalization rates, it was found in SA that the length of hospital stays was far shorter (3.5 vs 8 days). If that’s the case elsewhere, then the risk of hospitals being overloaded will be further considerably reduced.
The omicron wave is now receding in SA, and hospitalizations have been far lower than during the delta wave six months ago.
Prof Tim Spector, lead scientist on the Zoe Covid study, said public messaging needed to acknowledge that Covid symptoms would appear more like a common cold to many of those infected.
“For most people, an Omicron positive case will feel much more like the common cold, starting with a sore throat, runny nose and a headache. You only need to ask a friend who has recently tested positive to find this out,” Spector, a professor of genetic epidemiology at King’s College London, told the PA news agency.
Recent data, including a study from Hong Kong, found that Omicron was less able to infect deep lung tissue but more able to infect higher bronchial tissue.
“It appears to be shifting towards a virus that infects higher up in the respiratory tract and is therefore adapting to be more transmissible partly because it is changing the cell types it infects,” Openshaw said.
“That would go along with it producing more common-cold-like symptoms. Those laboratory studies support what the Zoe app is telling us.”
I’m starting to get the feeling that Omicron will ultimately mark the transition from COVID being pandemic to endemic, which was predicted by many to be the ultimate outcome from the beginning. I just spent a week in Florida. The airports were packed with domestic and international travelers, and while masks were worn, there no longer seems to be a general fear of the virus. Hotel stays and visits to the crowded theme parks demonstrated this, as almost no one wore masks. My family did, but I’d say mask use was around 15% at the theme parks and 10% in hotels. Plus, like old times, bars and restaurants were packed with people very close to each other. I wonder how much of Omicron’s spread is simply due to people relaxing all of the COVID practices just due to no more fear of it. Even when folks mention it, the fear seems to be about testing positive rather than actually having the disease itself.
The study only covered a small group of people and has not been peer-reviewed, but it found that people who were infected with Omicron, especially those who were vaccinated, developed enhanced immunity to the Delta variant.
The results of the study are “consistent with Omicron displacing the Delta variant, since it can elicit immunity which neutralizes Delta making re-infection with Delta less likely,” they said.
Well that sounds like a positive side effect. Omicron: friend or foe?
So my vaccinated 10 year old is sniffly and coughing and feels like poop. The earliest I could get a test is Monday. And Dallas has vast testing capacity.
At this point I expect schools to be virtual for January, just because of logistics. Too many people quarantined, too many people who can’t get tested. It’s not even about stopping spread, it’s just logistics.