A week ago, South Africa reported the B.1.1.529 variant, commonly known as omicron, to the World Health Organization (WHO). Since then, more than 200 cases have been detected worldwide according to the platform. These include South Africa (128 cases), Portugal (13), the UK (13), Germany (5) and Belgium (1). One case has been diagnosed on the French island of Réunion. For the time being, Luxembourg has reported no omicron infection.

How effective are the covid vaccines currently used against the omicron variant?

Claude Muller: It is considered a variant of concern because it has more than 30 mutations in its spike protein, the protein on the surface of the virus through which it can infect the human cell. That's a lot compared to the others. Delta, for example, has only eight. In concrete terms, some antibodies of people who have been vaccinated or have had the virus may no longer be effective in neutralising the virus. We would therefore be less sure of their protection.

Is it more dangerous or transmissible than previous variants?

When it mutates, the virus can change its properties. It can bind more or less well to its receptor. If it binds better, this means that infectivity increases and that it is better distributed in the population. For the moment, we can't say. Although, in general, viruses tend to become more infectious because it gives them a vital advantage.

[According to the National Health Laboratory (LNS), “preliminary data suggest similar clinical behaviour, without unusual symptoms and including asymptomatic cases”, editor’s note.]

What are the chances of it coming to Luxembourg?

It could happen tomorrow or in several weeks. Now that it is known to be in neighbouring countries, the risk of introducing it into Luxembourg is obviously high because we have a large flow of people crossing the borders every day.

Will the omicron variant replace delta as the majority variant?

If it is more infectious, there is a great chance that sooner or later it will replace delta and, like delta, spread rapidly around the world. If it is at the same infectious point, it may well be that the two co-circulate.

Laboratories are already working on a new version of their vaccines targeting the omicron variant. Wouldn’t it be wiser to wait before getting a booster dose?

No, absolutely not! The vaccines we have increase immunity and protection against the variants that are predominant in the world. [In Luxembourg, all cases detected in the last weeks were attributed to the delta variant, according to the last LNS report published on 26 November, editor's note.] And probably also, at least to some extent, against omicron, even if this is not a guarantee.

If you have some immunity to the background, there is a good chance that it will protect against at least one severe disease from this variant. There is no reason not to do the third dose in view of a vaccine that will only come in two to four month. [Pfizer and Biontech have announced a delay of 100 days, Moderna several months, editor’s note.] 

What happens if you get your booster dose and two weeks later the new omicron vaccine comes out?

If omicron is really different and escapes immunity, then it can be considered a different virus. It’s like a vaccination against a different virus, so there’s no problem doing it right after the booster dose.

What if the variant is not strongly different?

You don’t have to wait very long to do the fourth dose adapted to omicron.

What will happen to the old doses after the new vaccine is released?

If omicron continues to circulate with delta, or if there is a fear that delta will come back because immunity is waning, the next vaccinations could be a mix of both: a delta vaccine and an omicron vaccine. This is already done for other paediatric vaccinations with up to six vaccines in the same syringe (e.g. the hexavalent vaccine against tetanus, diphtheria, polio, pertussis, Haemophilus influenzae b meningitis and hepatitis B).

If the next time we do a booster, there is only omicron circulating, it would be a monovalent. In any case, the delta variant will not disappear overnight. We do what we do when a stockpile approaches its expiry date and we have too much: we offer the remaining doses to other countries that need them.

Much has been said about the effects of the second dose of Pfizer’s vaccine being more violent than the first. Of course, this depends on the serum used and the situation of each person. But what can be said about the effects of the booster dose?

I don't know any data about the effects of the third dose.

This story was first published in French on . It has been translated and edited for Delano.