Since then a similar notion has been appearing in the mainstream media. (Isn't it good to be ahead of them again!). For example the Guardian ran a story this week headlined "Omicron is ‘not the same disease’ as earlier Covid waves, says UK scientist". That's Sir John Bell, regius professor of medicine at Oxford University and the UK Government’s life sciences adviser.
The last week has also allowed us to get a better understanding of Omicron disease, although there are still some major uncertainties.
Let's examine what we do know, and what we don't, and consider:
- Whether it would be helpful to regard Omicron as causing a different disease, let's say COVID-21, regardless of official World Health Organisation conventions and names
- Whether the Government is right to avoid further disease prevention controls (which is the positive side of 'restrictions')
FIRSTLY, A BASIC INTRODUCTION TO CORONAVIRUSES
The virus that causes COVID-19 disease is officially called SARS-COV-2. It is one of seven types of coronaviruses found in humans, with many more found in other animals such as bats:
These spike proteins bind to a receptor on human cells, which allows the virus to infect the host cell. In the case of SARS-COV-2 and some other coronaviruses, the receptor is called ACE2 "Angiotensin-converting enzyme 2".
‘Variants’ are slightly different from each other, especially in having different spike proteins. Here are the changes in Omicron::
Simplistically for SARS-COV-2:
- The different spike proteins in the different variants have different binding capabilities. The better they bind to the ACE2 receptors, the faster the disease will spread from person-to-person and within each individual (see update in this post, re Omicron using a different mechanism)
- Differences in the body of the virus determine how severe the disease will be. Especially the RNA it contains
The four viruses that have mild symptoms like ‘common colds’, with only occasional serious symptoms, spread at different rates. At the other end of the severity spectrum, SARS-COV-1 and MERS-COV viruses produce much more serious disease (SARS and MERS respectively). Too often including death. But fortunately these two viruses do not spread easily, and so were relatively easy to stop spreading much further outside of the local area in which they were first found.
The fear after SARS and MERS was that there could be another coronavirus that spreads more quickly and easily, whilst also causing moderate to severe symptoms.
SARS-COV-2 is that virus family, with moderately bad symptoms (between common colds and SARS/MERS), with variants that have become increasingly good at infecting people:
Omicron is the fastest-spreading variant so far. But how serious is it?
LET'S FIRST CONSIDER LONG COVID
A significant proportion of people who have been infected byearlier variants of COVID-19, whether they have been hospitalised or not, have long term symptoms. Longer than three months, and sometimes longer than a year. These may be ongoing symptoms similar to originally experienced, or additional symptoms. Collectively called LongCovid.
We need to realise that it is not just cells in the respiratory tract that have ACE2 receptors. These are present in many organs including heart, intestines, kidney, gallbladder and testis. Yes you men, your testicles!
When SARS-COV-2 gets into the bloodstream, as can happen when infected cells burst:
- The virus is transported to other organs, where cells can become infected, damaging the organ
- The virus also causes microclots in the blood, which can themselves cause organ damage. The brain is especially susceptible, with a common symptom being fatigue and cognitive impairment or ‘brain fog’
The higher the case rate, the higher the number of LongCovid cases:
- Affecting the lives of a large number of people, with worst cases not having the health to work
- Putting additional strain on GPs, who are already over-stretched
- Putting additional strain on NHS specialist services, taking expert medics away from dealing with other health conditions
In addition, a proportion of people will have long-term and sometimes severe lethargy. This can be the body’s response to any severe illness. Lethargy is a common complaint of people who have had COVID-19, even mildly.
But how common is LongCovid in people who have had Omicron? As discussed below, Omicron has attributes that could make LongCovid more common. Too early to tell, but the risk is more LongCovid with Omicron - potentially worse symptoms in a higher proportion of people.
WHAT WE KNOW ABOUT OMICRON SO FAR
Speed of spread
All viruses can mutate as they replicate. SARS-COV-2 mutates less than many other viruses. But it still mutates, to produce different variants such as Omicron. This has mutations on the spike protein which has three results:
- Even when the body’s immune system is primed through vaccination or prior infection, the system does not recognise Omicron as the same threat as earlier variants. Omicron therefore substantially ‘escapes’ our immunity to other variants
- It looks like Omicron’s spike proteins bind more easily to host cells than the original virus and earlier variants
- As a result, people become infectious more quickly, in just a few hours
Studies on how fast Omicron can spread include this published by Imperial College London last week:
1. "In human nasal airway epithelial cells (HAE)
Omicron showed a large early replication advantage, yielding viral load
titres ~100-fold higher than for Delta by 24 hours post infection." This graph has a log scale, so adding 2 means multiplying 100 times:
Omicron spreads very fast!
Severity of Symptoms
If Omicron caused only mild symptoms similar to the four common cold coronaviruses, we could just let it spread, and everyone have maybe a couple of days unwell and off work. Much like colds and flu
If we could easily test for specific variants, there could be different rules for self-isolation with Omicron, and we could possibly be more relaxed about high case rates, subject to the uncertainties below.
Fortunately it does seem that symptoms are mild, at least for people who are well jabbed. Hence the UK Government putting stress on people getting the booster.
The common symptoms of Omicron are different to those for Delta and earlier variants.
- Delta and earlier variants:
- Continuous cough
- Loss of taste and smell
- High temperature
- Omicron:
- Like a common cold (like some other Coronaviruses)
- Sore throat, and importantly a hoarse/scratchy voice as the first symptom
- Runny nose
- Different
- Headache
- Fatigue
WHAT ARE THE MAJOR UNCERTAINTIES?
But there are still some major uncertainties, as Omicron is so new, even after pooling knowledge from around the world:
- Omicron infection has been mainly in younger generations. We don’t yet know how severe infection will typically be in older generations and for others who are at higher risk.
- We don’t know what proportion of those infected will typically require hospital treatment, of those who will need intensive care, and how many will die. We need to know by age group. Whilst the proportion of serious cases may be below that for earlier variants, very high case rates could still mean large numbers requiring hospital care.
- We also need to know the difference for people of different vaccination status. Omicron is likely to be more serious for the unvaccinated. Hopefully vaccines may make symptoms less severe, even if vaccinated people are still getting infected
- As hospitalisation lags infection by a week or two, it is still too early to tell whether the surge in cases in the last week or so will translate into high numbers requiring hospital treatment. Though early indications are not good. That's because if high numbers do result, it will be too late to do much about it. High numbers infected and about to require hospital treatment will already be 'baked in’
- LongCovid: We don’t know what proportion of people infected will have long term symptoms. More or less in number? Different symptoms, perhaps? But as Omicron spreads more quickly through the body, our intial assumption should be a higher proportion of those infected with Omicron may suffer from LongCovid, more seriously.
SO IS OMICRON CAUSING A DIFFERENT DISEASE?
We know:
- There is a different set of initial symptoms, somewhat milder than for Delta and earlier variants
- Cases are spreading and growing far more quickly than earlier variants
- Omicron is ‘escaping’ immunity, both from vaccines or prior infection
- Therefore the best Government response to Omicron could be different from that for earlier variants
It is therefore sensible to regard the disease as different, with a different name. With 2021 almost at an end, let’s call it COVID-21. (See Update at foot of this post)
We effectively have two overlapping pandemics:
- COVID-21 caused by Omicron
- COVID-19 caused by Delta and other variants
Yet our tests cannot yet distinguish Omicron from other variants. We have to fight it as if it were a single COVID disease
WHAT ARE THE IMPLICATIONS FOR THE UK GOVERNMENT’S RESPONSE?
We asked earlier “Whether the UK Government is right to avoid further disease prevention controls (otherwise known as 'restrictions')”
In reality, we have to manage all COVID-19 infections in the same way at the community level, given:
- So many uncertainties on the severity of Omicron disease, beyond relatively mild initial symptoms
- No easy way to identify which cases are Omicron
But where an individual is clearly infected with Omicron, it is more useful to think in terms of a different ‘COVID-21’ disease. “COVID” could be the term covering both 19 and 21.
In the UK, the length of self-isolation has been reduced from '10 days' to '7 days'. Though the definition of day differs, so that it actually means nearly 4 days earlier., not 3 . Counting infection day (or positive test) as day zero, the original rules were that infected people should self-isolate for the next 10 days, and can stop self-isolating as day 11 starts at 0001 hours. Subject to certain conditions, the new rules allow someone to stop self-isolation after a negative test on day 7, nearly four days earlier than before. (not 3). The USA has gone a stage further, reducing that to 5 days.
Five days would be good for Omicron, to avoid as much disruption as Omicron is causing, with organisations having to close or run on substantially reduced staff. The NHS is currently suffering the combination of high case rates and being short staffed. Furthermore the worry is the risk of major disruption to the food supply chain.
Perhaps 5 days may be comfortable for cases of Omicron, if we can be confident of low consequences, such as low incidence of LongCovid. But 5 days is difficult to accept for other variants, where the co0nsequences of infection we know to be serious in many cases.
Or could we say that Omicron is now so dominant, the chance of catching another variant is substantially reduced? If that was the case, perhaps we could treat all infections as Omicron and potentially be more relaxed on restrictions.
But we have major uncertainties of the severity of Omicron:
- Generally
- In older people, and others at higher risk
- For LongCovid
There are also unacceptable risks to society due to so many people being off work ill. It is therefore madness to allow high case rates. Hospitalisation levels are only one consequence.
Whilst nobody wants to see tougher restrictions, not to do so is taking enormous risks with NHS, food supply and much else. Action is needed to reduce spread of the disease. There’s no time to lose, given how quicjkly Omicron / COVID-21 is spreading.
As Imperial College says in conclusion of their report last eyar, where NPI means Non-Pharmaceutical Interventions such as lockdowns:
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