Omicron’s mixed bag – update

To start brightly, it seems that the evidence trickling in hints at good news. This report from a South Africa hospital shows that far fewer patients with Omicron are needing treatment with oxygen, and that the pattern is different from previous waves; of 42 patients on their wards, 19 are on oxygen, three on high dependency and one on ITU.

There are also suggestions that South African ITU’s are not filling up; so when patients are admitted with the Omicron variant, they are staying three times shorter, signifying less severe illness. However, things are changing rapidly and in the last few days it seems there have been significantly more admissions in a country where most infections are with the Omicron variant. Also, gloomily for us, they are in the middle of summer.

In the USA there have been 40 cases so far, with mild symptoms and one hospital admission. One in 40 is not especially good news, but numbers are too low to make any conclusions. That is why, over here, we are less sanguine; we are facing winter, the public sector is already struggling and any increase in cases and admissions will make life difficult.

So back to the labs; what is the latest on the big issues of transmissibility, virulence and immune escape?

The three big questions:

Transmissibility; Yes it does seem significantly more transmissible, being able to infect 3-6 times more people than Delta, according to this analysis in Nature. In the UK the HSE expect that at least 50% of all infections will be with the new variant within the nest few weeks – in other words, over Xmas.

Severity of illness: So far it does not seem to cause more severe illness, but this is based on very preliminary data from the South African population where the climate, season and age of patients are very different from Europe. Given that this is very early days, it is too early for optimism on this, even if there is some to hang on to.

Vaccine evasion: Yes it does partially evade the vaccines and immunity from previous infection. This paper shows you need many times more antibodies to neutralise it, but vaccine escape is not complete. Over here HSE stated half the early cases were in people who have been vaccinated – in other words, half the cases are in the 10% of people who are unvaccinated – again the numbers are too small to be reassured by, but they suggest that the vaccines continue to have a positive effect.

For those who have had boosters, or been double jabbed with an infection, early news from Pfizer is encouraging – in a press release Pfizer have said;

• Preliminary laboratory studies demonstrate that three doses of the Pfizer-BioNTech COVID-19 Vaccine neutralise the Omicron variant (B.1.1.529 lineage) while two doses show significantly reduced neutralisation titres (levels)
• Data indicate that a third dose of BNT162b2 increases the neutralising antibody titres by 25-fold compared to two doses against the Omicron variant
• Titres after the booster dose are comparable to titers observed after two doses against the wild-type virus which are associated with high levels of protection
• As 80% of epitopes (regions our immune system recognise) in the spike protein recognized by CD8+ T cells are not affected by the mutations in the Omicron variant, two doses may still induce protection against severe disease

By way of hedging their bets, Pfizer add:

“The companies continue to advance the development of a variant-specific vaccine for Omicron and expect to have it available by March in the event that an adaption is needed to further increase the level and duration of protection – with no change expected to the companies’ four billion dose capacity for 2022.”

In summary, it looks certain that Omicron will become dominant, and it is still hoped that it causes less severe infections, and a booster dose of vaccination is really useful, countering the immune escape of Omicron. So, for those vaccinated, a booster dose makes sense, as it does against other viruses like Hepatitis B.

Treatments

With new and better treatments coming along, we will have more options as this winter rolls on, The newer protease inhibitors continue to look promising and should be OK with the new variant – they will be available early next year. Some however, will fall by the wayside:

For anyone with vulnerabilities more options are available to prevent severe disease, and cell based immunity from previous vaccines will also have this effect, so Im keeping my fingers well crossed.

What next?

Plan B, that slight step up from Plan A means more mask wearing, use of the NHS Pass for certain events and working form home when possible and is a nod to prevention and now in place.

In summary, I’m hoping this winter will be very different from the last. At about the same time last year Delta was coming along to spoil Xmas 2020 plans. Delayed restrictions led, at least in part to our big wave over the New Year. Now we can do more testing, with all its faults and expenses and is now a part of the NHS pass requirements for those who are not vaccinated or recently infected. We also have more community immunity, more boosted vulnerable people, more treatments available and in the pipeline.

On the other hand, I remember well being a busy GP at this time of the year in any case. Infective agents like winter, they like crowds and the like poorly ventilated indoor environments.

I expect we will know much more in a weeks time.

Thanks for reading this blog – It’s a shame its such an interesting time. If you would like to leave any comments or questions. then feel free to do so and I will get back to you as soon as possible.