More than three million people in Germany have already received a booster vaccination. How does the third injection affect the risk of infection and the risk of severe disease? A look at the studies.
The number of new infections continues to rise – and with it the risk for both vaccinated and unvaccinated people to come into contact with the virus. On Thursday, the nationwide seven-day incidence reached 249.1, a high since the pandemic began. The number of new infections also climbed to a record high with 50,196 new cases within 24 hours.
How can the increase in the number of cases be slowed down? This is currently being debated in professional circles and in politics – the proposals range from a nationwide 2G regulation, an increase in the vaccination rate to the reintroduction of free citizen tests or contact restrictions. Another highlight is the booster vaccinations that are already being used in Germany for vulnerable groups. Nationwide, there are currently more than three million such booster vaccinations. MRNA vaccines are used – i.e. the vaccines from the manufacturers Biontech / Pfizer and Moderna.
The federal and state health ministers announced the booster for everyone last week. The Standing Vaccination Commission (Stiko) also considers a booster vaccination for all basic immunized persons to be sensible in the medium term, as the committee explained on Monday. “Immunological and infection-epidemiological reasons” speak for this. The refreshment should take place “at the earliest six months after completion of the basic immunization,” said the Stiko. The statement suggests that the Stiko could recommend the booster to everyone shortly. At the moment, however, this is not the case.
for which groups the Stiko currently recommends the booster.
From a scientific point of view, what speaks in favor of the booster? How much can the third-party vaccinations curb the infection rate? And how do you strengthen the protection against severe disease? There are already data and findings from studies on all of these questions. An overview.
Why is a booster needed at all?
It is already known that the immune protection decreases over time after vaccination. The result can be so-called breakthrough infections – i.e. diseases with the coronavirus despite a full vaccination. Of more than 3.4 million electronic medical records, it showed that the protection against infection of Covid-19 vaccinated persons (Biontech / Pfizer) against the virus variant Delta fell from 93 percent to 53 percent over the course of five months. This is a clear decline, but the almost 53 percent protection is still an acceptable value – compared to the zero percent that non-recovered unvaccinated people have.
There are essentially two reasons for the effect: On the one hand, there is the already mentioned vaccination effect, which decreases over time. But the highly contagious virus variant Delta also plays a role. It can also infect people who have been vaccinated and potentially become carriers – albeit much less often than those who have not been vaccinated.
The good news is that such breakthrough infections are usually mild, as the study from the USA showed. At 93 percent, the protection rate against severe courses with hospitalization remained very high over a period of six months.
If the protection against severe gradients is good – why do you need the booster?
As is so often the case in medicine, general statements do not apply to every single person. In relation to vaccines, this means: Although the corona vaccines protect the majority of people very reliably from severe Covid-19 courses, there are groups of people who benefit less.
It is already known that the immune response of certain people after a first completed series of corona vaccinations can be weaker than that of other people. So-called “low responders”, for example, produce fewer antibodies than most other people and are therefore less able to bind the virus. Who belongs to this group of people: They are mainly people with autoimmune diseases, certain types of cancer, the elderly as well as patients who have received a donor organ and therefore take drugs that suppress the immune system. For many of these people, Stiko recommends a booster vaccination, including people over 70 years of age.
But what about the younger ones? In principle, they have a lower risk of becoming seriously ill because of their age alone. The basic immunization also protects them. For them, the “infection epidemiological reasons” to which the Stiko refers in the above-mentioned communication predominantly come into play. This means: A booster vaccination not only strengthens the immune response in older people, but also in younger people. As a result, vaccination breakthroughs are less common. If a sufficiently large number of younger and middle-aged people are third-vaccinated, this has an impact on the infection process.
How much the booster can reduce the number of so-called breakthrough infections was recently shown with more than 10,000 participants, in which data from people who had been vaccinated twice were compared with those of people who had been vaccinated three times. The mean time since the last vaccination was eleven months for all persons. One group was given a booster, the other an ineffective placebo. In the following two and a half months, five people in the booster group fell ill with Covid-19. There were 109 cases in the double vaccine group. This corresponds to a booster effectiveness of 95.6 percent.
Are there any other data on the booster?
Yes there is. First and foremost from Israel, a country that started the vaccination campaign very early and has therefore been “boosting” it for a few months – even for younger generations. The journal “The Lancet” recently published a study by researchers at the “Clalit Research Institute” in Tel Aviv, which suggests that the booster also increases protection against severe disease and deaths – a kind of additional protective screen. () However, it is unclear how long this will last – the follow-up period in the study was quite short with an average of two weeks.
There is also evidence that the successful booster vaccination campaign in Israel has helped break the fourth wave of infections in the country. It is questionable, however, whether a similarly strong effect could also be observed in Germany, which above all
What follows from this?
Elderly and risk groups can use a booster to further reduce their risk of serious illness and hospital admissions. The booster is particularly useful for them because they were usually vaccinated a long time ago and many people in the original priority group 1 should be among the so-called “low responders”.
For younger, healthy people, the transmission protection through the booster is in the foreground: People who have received a third vaccination are once again less likely to be infected with the coronavirus, which can prevent the virus from being passed on and offers additional protection for vulnerable groups.
Experts such as Stiko boss Thomas Mertens are urging to prioritize booster vaccinations as well. First of all, it should be the turn of those who benefit greatly and who have been vaccinated longest, risk groups and the elderly. There is also a spotlight on the so-called vaccination gap, i.e. the group of those millions of people who are still without any protection. The closing of the vaccination gap has “top priority” given the current figures, the virologist Christian Drosten wrote on Twitter last week.
Jan Fuhrmann, an expert in mathematical epidemiology at Heidelberg University, explained why this is so important to the DPA news agency: Overall, the difference between the risk of a severe course between completely vaccinated and unvaccinated people is greater than that between people with and without a booster vaccination.
Source From: Stern
