Fact check: Is Omikron more contagious to the vaccinated than to the unvaccinated? | Knowledge & Environment | DW

The number of infections with Omikron is rising rapidly in numerous countries – and thus the false claims. Currently, it is often claimed that vaccinated people are more likely to become infected than unvaccinated people. Study data is used for this purpose. We have looked at two concrete examples.

RKI admits errors in published data

“The German government states that 96 percent of omicron cases have been vaccinated,” writes one user on twitter. In addition, an alleged graphic from the Robert Koch Institute circulates online, a pie chart with data from November 21 to December 27. According to this, 69 percent of the people in Germany who were infected with omicron were fully vaccinated, 27 percent even had a booster vaccination – and only four percent were unvaccinated. But are the numbers really right?

This graphic circulates on social networks and aims to prove that omicron is more contagious to the vaccinated than to the unvaccinated. But that’s wrong.

At our request, a spokeswoman for RKI wrote to us that the graphics did not come from the department – but the relevant figures were published in a weekly report on 30 December 2021.

“Yes, the section of the weekly report unfortunately contained an error (instead of 186 there are 1,097 unvaccinated people with omicron infection),” the spokeswoman wrote. During an update, a number was then forgotten and improved again on January 3rd. This fix has been clarified in the updated report.

Either way, the published data are not suitable for calculating vaccination efficacy. The spokeswoman refers to RKI’s website. “With an increasing vaccination rate, more and more vaccinated can be expected among the sick,” it says. In addition, the efficacy of the vaccines is not 100 percent, but greatly protects against severe disease progression with COVID-19.

It is also clear that the more infections there are overall, the more infected there will be among those who have been vaccinated. After all, 71.6 percent of the population in Germany (as of January 7) is fully vaccinated. However, so-called vaccination breakthroughs do not mean that the vaccinations do not work.

Booster vaccination greatly increases protection

Preliminary studies show that the vaccines against the omicron virus variant no longer protect against infection as well as with other variants. However, the results also show that basic immunization is likely to still protect against a severe course for a certain period of time.

And there is more good news: The first international study results show that a booster vaccination significantly increases protection again. A study conducted by Biontech / Pfizer even comes to the conclusion that three vaccinations against omicron are as effective as two vaccinations against the wild type of virus.

Virologist Wolfgang Preiser also confirmed the effectiveness of booster vaccinations in a DW interview. He is one of the researchers in South Africa who discovered the omicron mutation. “The important thing is that we [in Südafrika, Anm. der Red.] has almost no vaccinated seen in the intensive care unit, “explains Preiser. And: The vaccinations continue to provide good protection against disease or death. The vaccines are therefore still important in the fight against corona.

Danish data are also misinterpreted

Vaccination critics are also currently using a study from Denmark to show that the effectiveness of the vaccines from BioNTech / Pfizer and Moderna against Omikron is even negative after three months. A Twitter user writes: the probability of an omicron infection is 76.5 percent higher for those vaccinated with BioNTech than for those who are not vaccinated – for those vaccinated with Moderna, it is 39.3 percent higher.

The study, which has not yet been reviewed by other researchers, addresses the question of the extent to which the two vaccines protect against an omicron infection. The estimated effect in the study comes from a comparison of the infection rates for twice vaccinated and unvaccinated in the first few weeks after the variant was discovered in Denmark.

The vaccinated behave differently from the unvaccinated

In fact, the effectiveness of the two vaccines in the study drops to negative territory after three months. We spoke with Christian Holm Hansen, co-author of the study and epidemiologist at the Statens Serum Institut in Copenhagen. According to Hansen, the negative values ​​are a statistical bias.

“One reason we are seeing a higher incidence in the vaccinated population is that vaccinated people are being tested more often than unvaccinated people,” he explains. This would also mean that more cases would be discovered there. In addition, only vaccinated and healthy people are allowed to travel or attend events – which is why they are more likely to be infected there. However, this does not mean that they are more likely to become infected due to the vaccination. The authors of the study pointed this out in their study.

In addition, the vaccinated part of the population in Denmark is significantly larger than the unvaccinated. About 79.46 percent of the population (as of January 5) is fully vaccinated there.

In addition to the mathematical bias, the study also has another weakness. It only examines how many, whether vaccinated or unvaccinated, have been infected – but does not distinguish between mild or severe disease.

Conclusion: Data from Germany and Denmark do not prove that the vaccines do not work against omicron and that the corona variant is more contagious for the vaccinated than for the unvaccinated. They are used manipulatively to speak out against vaccinations. In their basic immunization, the approved vaccines are less effective against omicron than against other variants – but still offer relative protection against serious cases. Preliminary studies also show that booster vaccinations greatly increase protection against infection and severe disease progression.

Collaboration: Ines Eisele

Leave a Comment