Vaccination and virus variants: does the booster come after the booster?


Status: 11.01.2022 3:59 p.m.

The booster vaccination increases the protection against Omikron. But why does it fade over time? Will you soon need booster vaccinations every three months? The most important questions and answers.

How does the booster vaccination work with Omikron?

After the basic immunization – i.e. after two vaccinations or, in the case of the Johnson & Johnson vaccine, after one vaccination – the protection against infection at Omikron diminishes very quickly, says Sebastian Ulbert, vaccine expert at the Fraunhofer Institute for Cell Therapy and Immunology. The booster vaccination significantly improves this protection, at least for the first time after the vaccination, because more antibodies are formed again.

The virologist Christian Drosten from the Berlin Charité referred in the podcast “Coronavirus Update” NDR-Info based on Danish study data, which showed that the third vaccination greatly reduced the risk of Omicron infection and made the difference in the current spread control. On the other hand, basic immunization is still very good at protecting against serious illness, says Ulbert.

Immunologist Carsten Watzl refers to a report by the British health authority UKHSA on the effectiveness of vaccination against a severe course with Omikron, which leads to hospitalization. According to this, the protection up to six months after the second vaccination is around 72 percent, after the booster even around 88 percent.

How long does the protection last after boosting?

How long the protection will last in each case cannot be reliably said in the wake of the still young omicron wave, says Ulbert. The booster vaccination expands the protective effect at least considerably and evokes an increased immune response.

Why is the booster protection dwindling?

In the discussion about the further vaccination strategy it seems clear: Even after the booster vaccination, the protection against infections will diminish again over time. “The many antibodies that you have after the booster are lost again over time. The reason for this is that the immune system reacts to the vaccination as it does to an infection and first of all produces a lot of antibodies,” explains Watzl.

At some point, however, these would no longer be needed, so that the number would be significantly reduced. This then increases the risk of becoming infected again.

Is the booster booster necessary?

According to immunologist Watzl, close-knit vaccination protection is currently still needed because the most important goal is to curb the spread of the virus. After all, not all are adequately protected from severe events. Looking to the future, however, the primary goal is to protect against severe disease – and this is decreasing much more slowly. Regular boosters could then be useful for people from risk groups. In the case of younger and healthy people, however, it is conceivable in the future that regular booster vaccinations will no longer be necessary as long as the virus does not change significantly.

Israeli data on the fourth vaccination had recently shown that it did bring about a renewed increase in antibodies. It was “good, but not sufficient,” said Gili Regev, head of the study, about the preliminary results. Shortly after the fourth vaccination, one was back to the same antibody level as shortly after the third – and it could not be the goal to be vaccinated against the coronavirus again about every four months. For at-risk groups such as senior citizens, the fourth dose is the right way for the time being – for the rest of the population it is questionable.

Why does vaccination not protect against omicron infection as well as against infection with other variants?

The vaccines seem to protect less against omicron infection than against other virus variants such as Delta. This is suggested by more and more registered infections in people with basic or even booster vaccinations. “The vaccines were developed based on a specific sequence of the spike protein that is on the virus surface. In the meantime, however, there are variants that have changed the spike protein at crucial points,” explains vaccine expert Ulbert. As a result, this virus variant is no longer recognized so well by the immune system. In addition, with more contagious variants, fewer viruses are usually sufficient for an infection.

How well does the vaccination against Omikron work in general?

When it comes to the question of the vaccine effect, a distinction has to be made between protection against infection and protection against serious illness, says immunologist Watzl of the German Press Agency.

“The pure protection against infection with Omikron will always be suboptimal with the current vaccines,” said the Secretary General of the German Society for Immunology. But: “The vaccines still do what they are supposed to: They protect against severe courses and we are currently seeing that at Omikron.”

An analysis recently presented by the British health authority UKHSA indicates that booster vaccinations of the particularly vulnerable group of seniors offer a high level of protection against severe disease even with Omikron. Three months after the third vaccination, the protection against hospitalization for people aged 65 and over is around 90 percent. The protection against corona infection with mild symptoms, on the other hand, is only around 30 percent, as the preliminary data show.

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