What do we know so far about the omicron variant?

Last Friday evening went a bit differently than expected for everyone. I was enjoying a glass of wine by the fireplace at my parents‘ house when I suddenly received the following message on my phone: ’Outbreak Management Team advises hard lockdown: almost everything must close.’ You can't be serious? Hospitality, shops, theaters, and gyms closed again? For how long? And will it even make sense? Is there still a small chance that there won't be a full lockdown? All these questions were racing through my mind.

Unfortunately, we indeed received bad news the next day: a hard lockdown starting Sunday, until January 14. Previously, we always had a few days to get used to the new measures, but this time we didn't even get one day. We were going straight into that lockdown, the next morning at 05:00. Quite intense, really. But well, that omicron variant is spreading rapidly, so this decision obviously had everything to do with time. At the same time, we hear around us that this variant makes people much less sick than earlier coronaviruses. So what's going on exactly?

OMT member and professor of molecular epidemiology Marc Bonten says the following about this decision: ‘Bringing the R-number below one, as was always the goal in previous lockdowns, is not so much the aim this time. Everything is aimed at preventing hospital infections from rising too much. Therefore, we want to counter as many contacts as possible to reduce the spread of the virus.’ That all sounds quite plausible, but what do we actually know so far about this new omicron variant? There is still a lot unclear, but below I share a few important questions with answers.

Where does this omicron variant come from?
On November 24, this variant was first identified in South Africa, but that doesn't necessarily mean that the variant comes from there. South Africa has relatively many advanced laboratories, so the chance is greater that the variant is picked up there. In the meantime, omicron has been found in many countries. The RIVM reported that omicron was detected in earlier test samples from November 19 and 23 in the Netherlands, which is before the variant was officially identified in South Africa. identified in South Africa. A few days ago, I even read a news article about Chinese scientists who thought that the omicron variant originated from mice, but this theory has been debunked by various virologists due to a lack of sufficient research. Where the omicron variant actually comes from remains a big mystery.

Are we protected against omicron by our built-up immunity?
The omicron variant can evade built-up immunity against earlier variants of the coronavirus. Omicron has about fifty mutations in the genetic code of the virus compared to the original variant from Wuhan. Many mutations are on the spike protein, which the virus uses to gain access to the cell. Due to the large number of mutations in the spike protein, the antibodies produced against earlier variants will be less effective or even ineffective. Studies also show that antibodies generated after vaccination are less effective against omicron than against beta and delta, the earlier variants of the virus. 

Does omicron spread faster than earlier variants?
The fact that omicron spreads so quickly does not mean, according to Jaap van Dissel, that this variant is more contagious than, for example, the delta variant. Omicron simply spreads much faster in populations with high immunity, which has been built up through vaccination and infections with earlier variants. This variant is therefore not very affected by antibodies. People who were vaccinated about six months ago probably have too few antibodies against omicron and therefore get infected more often than with the delta variant. They then pass this on, of course.

Is omicron the most common variant in the Netherlands?
At this moment, the number of omicron infections is still in the minority, but according to the RIVM, the number of infections with the omicron variant is increasing so rapidly that omicron will likely become the most common coronavirus variant before the end of the year. https://www.rivm.nl/nieuws/snelle-opmars-omikron-in-nederland Virologist and OMT member Menno de Jong reported that last Wednesday almost 25 percent of all coronavirus infections in Amsterdam were due to the omicron variant. The week before, this was still 2.5 percent. The virus is spreading very quickly. 

Is this omicron variant less pathogenic?
From South Africa, we initially received reports that this variant would be less pathogenic , but RIVM leader Jaap van Dissel reported last Wednesday that data from Denmark unfortunately contradicts this. It appears that people infected with the omicron variant have about the same chance of ending up in the hospital as with older variants. Scientists say it is still too early to know whether people become sicker from omicron than from other virus variants. 

Do vaccinations and previous infections protect against severe illness and death?
Vaccinations and previous infections provide less protection against infection with this variant, but they do protect against severe illness and death. This is because a different part of the immune system is involved: the so-called cellular immune system or T-cells, which according to De Jong are less sensitive to changes in the spike protein: ‘T-cells do not prevent infection, but they fight the virus after infection. This leads to a milder course of the disease.’ This applies to delta and possibly also to omicron, but not enough research has been conducted on that yet. 

Will boosting work against the omicron variant?
Initial foreign studies show that vaccinations given earlier this year work less well against omicron, but according to Jaap van Dissel, boosting can mitigate the effects of omicron . Boosting improves individual protection against infection and probably also individual protection against severe illness and death. Let's hope so.

Sources: Volkskrant, Het Parool, RIVM, UMC Utrecht