It is now just over two weeks since I wrote the piece “Omicron – How worried should we be?” and, whilst we now know more about this latest variant, there is still much we don’t know.
Specifically we don’t know if the next few weeks will see a surge in hospital admissions and an NHS overwhelmed to the point a national lockdown is needed once again or if we will be emerging relatively unscathed from this latest development.
Scanning headlines one can find anything from the doom laded to the overly optimistic making it as difficult as ever for people to understand the current situation.
Mixed messages from the leaders of the four UK nations coupled with different restrictions between those nations has combined with a lot of recent political fallout to confuse things even further. (1) (2)
So what do we know at the present time?
Omicron is more transmissible than previous variants.
Without a doubt the Omicron variant is more infectious than any previous variant.
Data from South Africa (where Omicron was first identified) shows that in the four weeks from 13 November to 4 December 2021 there was an exponential rise in new COVID-19 cases and it was during this period scientists first identified Omicron. (3)
This is now being mirrored in the UK with Omicron cases doubling every two days with an R number estimated to be between 3 and 5. (The R number is the number of extra cases generated by one infected individual so one case of Omicron infection leads to between three and five more cases. Any value above 1 means infection is spreading.) (4) (5)
Cases are rising fastest in London and in the 20 – 34 years age group. (6)
It is highly likely that Omicron will become the dominant strain worldwide and it is far more likely to cause re-infections, ie: infect somebody who has already had COVID-19 caused by one of the earlier variants. (7)
However, when the rate of growth is this fast there is a limit to how sustainable it is. Eventually there are fewer and fewer people left to infect so whilst Omicron is on track to cause the biggest wave of infections to date, that wave is likely to peak and begin to drop off sooner than other waves.
Professor Chris Whitty, England’s chief medical officer, expects Omicron to peak quite quickly in the UK and then begin to slow down.
Speaking to the UK Government’s Commons Health and Social Care Committee on 16 December he said, “At a certain point, people will have immunity either from boosters or Omicron infection, which will also slow down the doubling time. I think what we will see with this, and I think we are seeing it in South Africa, is that the upswing will be incredibly fast even if people are taking more cautious actions – as they are – that will help slow it down, but it is still going to be very fast. It will probably peak really quite fast and my anticipation is it may come down faster than previous peaks, but I wouldn’t want to say that for sure.” (8)
Do we now know how serious Omicron is?
The honest answer to this question is, “No, we still don’t.”
Many commentators are putting great store in the fact hospitalisations and deaths have remained low in South Africa where vaccination rates are also still very low (~25% of the population are fully vaccinated) and concluding that therefore Omicron must be mild. (9)
However, direct comparisons cannot be made between the UK and South Africa for a variety of reasons.
South Africa has only recently had a very large wave of Delta infection and this may mean the population has a much higher level of immunity than expected. This boosted immunity brought about by infection may be as effective, or even more effective, than vaccinations in the fight against Omicron. We simply do not know yet.
South Africa has a much younger population and we know younger people fare better with COVID-19. By contrast the UK has a significantly higher number of elderly people who are the most vulnerable to COVID-19.
South Africa also had a large wave of Beta variant COVID-19 in 2020 which the UK did not. Beta has some similarities to Omicron which could mean South Africa had an immune advantage against Omicron from the outset. (10)
I have underlined “may” and “could” because this is what scientists have to contend with. Nothing is absolute when making comparisons between countries and until larger amounts of data about hospital admissions and disease severity are available specifically for the UK there is a limit to how much we can predict about what will happen here by looking at other countries.
As well as analysing data, scientists are working speedily to understand more about the Omicron variant itself. Researchers from the University of Hong Kong have found that Omicron replicates 70 times faster than Delta in the bronchi (the upper airways just below the trachea or windpipe) but 10 times slower than Delta in the lungs. This would explain how Omicron is managing to spread so quickly and could potentially be good news rather than bad as infections of the upper respiratory tract (the trachea and bronchi) are generally less serious and present with cough and cold type symptoms. Infection of the lungs (or pneumonia) is more serious and previous COVID-19 variants have targeted the lungs. (11)
So what are the implications for the UK?
I would argue that it is nothing to do with the infection rate per se. If millions of people simultaneously become unwell but recover quickly at home with no need for medical intervention there is little to worry about.
The problem will be the capacity of our hospitals to cope if there is a huge number of admissions.
If the Omicron variant has a hospital admission rate of 1% that sounds tiny...until you extrapolate it to 1% of 10 million cases, that’s 100,000 admissions. There are only 141,000 hospital beds in the whole of the UK. This is an extreme and very pessimistic example mathematically but I’ve used it to demonstrate why something that sounds unalarming, in this example the 1%, may not be the case in practice.
Even if Omicron proves to cause a milder form of COVID-19 researchers have to model for the worst possible scenarios even whilst hoping for the best.
If the NHS is not overwhelmed then one could argue that any number of infections is tolerable. What we are hoping for is that the combination of vaccinations, booster jabs and previous infections will keep our hospital admissions down. By early January we will know.
Vaccination is still key.
Unfortunately around 6 million UK adults remain completely unvaccinated by choice and hospitals are continually reporting that 90 to 95% of their sickest COVID-19 patients requiring ITU beds and mechanical ventilation are unvaccinated. (12)
It is now known that two doses of vaccine are less effective against Omicron than previous variants. However, a booster dose of vaccine significantly increases protection against symptomatic Omicron disease from around 40% for two doses to 85% after the booster. (13)
Note the phrase “symptomatic Omicron disease.” It is not the case that the current vaccines have no effect on Omicron, even a single dose is better than none at all. If the media begins reporting that the vaccines are "ineffective" or "failing to protect" it is important to ask, "What was the end point the failure is based on?"
There are many different layers of protection - protection from death, protection from severe disease, protection from mild disease, protection from asymptomatic infection. A vaccine that "fails" to prevent asymptomatic and mild illness but protects against serious disease and deaths is still doing a good job.
We need more time to know how well the vaccines are protecting against serious illness and death from Omicron but it is likely to be much better than the figure for milder cases of infection.
Several commentators have used an education analogy to explain why second doses and booster doses are needed. My own version is to compare how the body’s immune response responds to vaccines with studying GCSEs, A-levels and a degree. (14)
The first vaccine dose takes the body’s immune response to GCSE level knowledge of how to respond. The second dose gives the immune system A-level knowledge of how to respond and the booster dose enhances it even further to degree level. After the booster dose the immune response is quicker and broader, in short it is more effective. This is why so many vaccines, including those given to babies, require several doses.
If you have not had any COVID-19 vaccinations yet it is never too late to have your first dose - vaccination centres are offering first and second doses as well as boosters.
Travel and Christmas
Many countries are introducing travel restrictions because of Omicron. Given the fact Omicron has now been detected worldwide I would question the usefulness of such restrictions as they are going to have little impact on transmission of the variant. (15)
The larger impact from Christmas is likely to come through gatherings when the young mix with the old. Cases of Omicron have thus far spread primarily amongst the young and we simply do not know yet how the elderly will fare. It may be that their high levels of vaccination will protect them but we cannot take this for granted. There have not been enough older, vaccinated people contracting Omicron to be able to analyse their disease outcomes in a meaningful way. If cases do not rise in the older population after the Christmas and the New Year period then we will perhaps be able to relax a little. Until we know more it is prudent to take measures to protect older people and the clinically vulnerable at Christmas gatherings.
Minimise contact with other people for 10 days before seeing someone who is vulnerable if at all possible. Take a lateral flow test before visiting and continue to take them two to three times per week if staying for a longer visit.
Keep to the “Hands, Face, Space” mantra until we know more about Omicron.
By early January we will know if we are seeing a large increase in hospital admissions or not. I see enough to be concerned at the present time and, whilst life must go on, the one thing that I can say with absolute surety is that no harm will come from remaining vigilant and doing all we can to stay safe in our day to day lives.
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