Delta hardly plays a role in the current omicron wave. The previous version has made itself rare. But has she also disappeared? Experts don’t think so. A comeback could put the endemic goal in the distance.
It is hoped that Omicron will end the pandemic. But, is this really the truth? Many experts are anything but certain. Especially since an “old acquaintance” could celebrate a comeback after the Omicron wave: Delta. With the advent of omicron, the swan song to the previously dominant variant was already sounded, but perhaps it was hasty. Delta could be making a comeback in the not-too-distant future — and delaying the transition to endemic yet again.
Omicron is spreading rapidly, but is considered less dangerous than its predecessor, Delta. With omicron, so one thesis, one could possibly risk contamination. Or? “Let’s say that if we had to choose, Omicron would be better suited for such a contagion than Delta, for example,” said Richard Neher, a leading expert on virus variants, in an interview published by the University of Basel last week. One small word plays a big role in this assessment: better. Because the infection is not without risk. Not all infections were mild, and any long-term consequences are still unknown. On top of that, it seems that “infection with Omicron does not protect well against infection by Delta or other variants – at least if there was no immunity to Delta before infection”.
Omicron infection does not replace vaccination
Weeks ago, an admittedly very small study from South Africa depressed the mood of those who speculated on natural immune protection after an omicron infection. A research team headed by Alex Sigal tested how good the immunity really is after an omicron infection. The results caused disillusionment, at least for those who had not been vaccinated. Because while the antibody level in vaccinated people increased after the omicron breakthrough infection and the immune response improved – also against the delta variant – this was not the case in unvaccinated people. According to the study, their immune protection against Delta was significantly less strong.
Water on the mills of Minister of Health Karl Lauterbach. An omicron infection does not replace vaccination, he then commented. “The unvaccinated individual who gets Omicron infection now will have little protection against other variants in the fall,” he wrote. That is the price for being an escape variant. Attached is the somewhat cryptic sentence: “Little protection against serotypically distant fitness variants”. Omicron shows many mutations. This allows her to partially bypass the immune protection. Several experts, including virologist Christian Drosten, now assume that omicron could even be a new serotype.
Delta’s comeback possible
“So the omicron wave does not necessarily protect us from further waves in the future,” says Neher. Apart from the fact that new variants could emerge, he, like a number of other experts, thinks it is possible that Delta will come back after the wave has subsided. “Delta is a highly contagious variant that after some time, when immunity has waned, might regain an advantage over Omicron,” he explains. In other words, just because delta isn’t currently dominant doesn’t mean it can’t become so again. “We cannot be sure that Omikron will replace Delta,” confirmed Ulrike Protzer, head of the Institute for Virology at the Technical University of Munich, to the newspapers of the Funke media group.
The immunity after an omicron infection is “a bit different” than after a delta infection. “But if you’ve been vaccinated and then maybe had an additional infection, the immune system can deal well with new variants that could come up now,” said Protzer. In risk groups, however, it should be considered whether a fourth vaccination dose is necessary in the fall. The data from Israel, where the fourth dose vaccination campaign is currently underway, could help with the assessment.
Continue waiting for the endemic
“I don’t share the euphoria that Omicron is now leading us into endemics,” said Gérard Krause, epidemiologist at the Helmholtz Center for Infection Research in Braunschweig. Due to decreasing vaccination protection and infections with one or the other variant, many people have “partial immunity”, but that doesn’t help against every variant equally well. The question of when the pandemic will be over is primarily a question of how to deal with the pathogen, said Krause. “How many diseases are we willing to accept, how many can we prevent and at what price” – there must be social understanding on these questions. This is not a purely medical question, but a broad consideration.
As a pandemic spreads across countries and continents, diseases or pathogens that are persistent and cumulative in a limited region or part of the population are considered endemic. In the case of Sars-Cov-2, going endemic means the virus stays – people have to live with it, but it becomes less dangerous for the general population. However, Germany is currently still in the middle of the wave. On Tuesday, the Robert Koch Institute reported another high with a seven-day incidence of 1206.6. It is difficult to calculate when the peak of the wave will be reached. Experts are currently assuming that it should be in mid-February and that the number of infections will then slowly drop again.
And then? “Next winter I expect another sharp increase in the incidence,” Drosten told the “Tagesspiegel”. His appeal continues: the vaccination gap must be closed. Because it will not be possible, there is scientific evidence for this, to achieve transmission protection for those at risk via so-called herd immunity. “That also answers the question of whether everyone who has not yet been infected or vaccinated will eventually get this virus. Yes, they will. And then they have the initial risk of a severe course of the disease.”
Source: South Africa Study, University of Basel, preprint, daily mirror