NHS / ONS
SCIENCE – It’s been less than three weeks since South African researchers sounded the alarm about a worrying new variant, Omicron. In about twenty days, the data has accumulated and our knowledge about this new strain of the coronavirus is increasingly clear. And if there are still many unclear, we might as well say it clearly: the situation is not encouraging.
Admittedly, only 59 cases of the Omicron variant have been officially sequenced in France for the moment. But what is happening in the United Kingdom and Denmark, where the tracking of variants is more developed than in France, is rather worrying.
In summary, it appears that Omicron is spreading through the population much faster than any other variant so far, although the exact reasons are still unclear. At the current rate, it should be dominant by the end of the year in these two countries. And if for the moment, some clues may suggest that this variant causes less severe forms of Covid-19, this good news may not be enough to contain a new wave, even if it were confirmed.
The Omicron variant spreads very quickly
It is always unclear whether the circulation of the virus in one country will be similar in another. But in recent days, several analyzes have shown that the explosion of cases in South Africa cannot be linked to chance. This is a reflection of the ease with which the Omicron variant contaminates.
In an English report published on December 10, it is specified that Omicron cases are doubling roughly every three days. 48 hours later, a Danish weekly surveillance report also showed an extremely strong and very similar increase. Omicron is expected to account for 50% of Covid-19 cases on December 15 in the country.
Same thing according to the latest Scottish data, which estimates that Omicron will account for 90% of cases by December 20. Figures that perfectly match the estimates made for South Africa, such as the precise researcher Trevor Bedford.
It is unclear how much this advantage of Omicron over Delta is related to increased transmissibility or the ability of this variant to infect people who are normally immune. But it is certain that Omicron infects the vaccinated much more than the previous variants. 74% of cases in Denmark were doubly vaccinated. According to English data, a double dose of Pfizer is no longer effective at about 30% to protect against infection, but the third dose allows you to go back to a more acceptable level, remember epidemiologist Meaghan Kall.
These real-life data are still uncertain, as the number of cases is low at the moment, but they perfectly match the laboratory studies which detected a decrease in the effectiveness of our antibodies against Omicron.
Omicron lighter? Why you have to be (very) careful
In view of all these elements, it seems extremely likely that Omicron will impose itself in most countries, including France, in particular thanks to its ability to re-infect people who are immune (naturally or via vaccines). But could it not be serious? For three weeks, many researchers have wondered about the dangerousness of the Omicron variant.
Indeed, the first data from South Africa showed that if hospitalizations were rising, the curve was slower than that of cases. In England, no hospitalization linked to Omicron had been recorded and it was only this Monday, December 13 that Prime Minister Boris Johnson announced that at least one death was due to the variant in the United Kingdom. In Denmark, barely 1% of cases are hospitalized.
But several elements call for caution. First, we must remember that there is a delay between infection and the severe form of Covid-19 which leads to the hospital. Importantly, as was the case in previous waves, the Omicron variant seems to circulate first among young adults (logical, these are the ones who have the most physical contact).
“There are very few cases in high-risk groups, including the elderly,” notes Meaghan Kall.
This was also the case in South Africa, although this is changing, as epidemiologist Michelle Groome recalled on December 10 in a presentation of the situation in the country. Over the last three weeks, the proportion of contaminations linked to those under 20 has decreased, while it is increasing among the oldest. In one week, hospitalizations have certainly progressed less quickly than cases, but the increase is still 455% and mainly due to the unvaccinated.
As the note Eric Topol, on the hospitalization side, these milder cases are good news, but the bad news is “there are a lot more cases, so even if the severity is lower, the number can be high in absolute value”.
In addition, preliminary work suggests that vaccination, if it does not prevent infection with Omicron, should decrease the risk of developing a severe form. This would therefore mean that the risk is higher for the unvaccinated. However, we must not forget that around 9% of the French adult population is not vaccinated at all. Of these 9%, a significant portion has never caught Covid-19. If Omicron circulates so quickly, in particular thanks to its capacity to infect even the vaccinated, the risk, it is therefore that it ends up contaminating the unvaccinated very quickly. As a reminder, the first hospital wave only affected about 3% of over 65s and was enough to saturate hospitals.
There are still many uncertainties about the severity of the Omicron variant and we are not immune to good news. In any case, it seems likely that this new strain is needed in most countries, including France, and causes a large wave of cases. That it turns into a hospitable wave is not said, but it is necessary to prepare for it. Even the United Kingdom, which had been trying for 7 months to “live with the virus”, raised its alert level on December 12.
See also on The HuffPost: the United Kingdom raises its alert level, a first in 7 months