It can happen that people become infected with the coronavirus despite having been vaccinated twice. But that is not a reason to doubt the benefit of the vaccinations.
Over half of the population in Germany – exactly 52.6 percent – is considered to be fully vaccinated. You have now received all the necessary vaccine doses that are intended for the respective vaccine – two in the case of Biontech / Pfizer, Moderna and Astrazeneca and one for the single-use vaccine from Johnson & Johnson. “All available Covid-19 vaccines protect well against infection with the Sars-CoV-2 coronavirus and are highly effective against severe courses (…)”, writes the Federal Center for Health Education (BZgA).
Recently, however, there have been reports of people who have contracted the coronavirus despite having been fully vaccinated. Medical professionals refer to such cases as vaccination breakthroughs. They are not surprising. Already in the approval studies of the vaccines it became apparent that the vaccinations protect against corona diseases very well, but not 100 percent. () Vaccination breakthroughs also do not mean that the vaccinations are not working – or that vaccinated and unvaccinated people have the same risk of disease.
However, breakthroughs in vaccination should be closely monitored and investigated. For example, it can be determined for which groups of people the vaccination may protect less well or whether certain virus variants lead to vaccination breakthroughs more often. This is already known about cases in which people were infected despite double vaccinations:
What is a vaccination breakthrough?
The Robert Koch Institute (RKI) evaluates corona infections as vaccination breakthroughs if they occur in fully vaccinated people and are accompanied by symptoms. People are fully vaccinated around two weeks after the second dose – i.e. on the 15th day. The pathogen must be proven beyond doubt, for example with a PCR test.
How common are vaccination breakthroughs?
The RKI has been listing the individual vaccines since February 1, 2021: 5,766 after a completed vaccination series with Biontech / Pfizer, 214 with Moderna, 331 with Astrazeneca and 601 with Johnson & Johnson. The Biontech / Pfizer vaccine forms the backbone of the vaccination campaign and has been by far the most widely used. Vaccination breakthroughs are also observed correspondingly more frequently.
The data show how rare vaccination breakthroughs are. By July 29, 2021, just over 40 million people in Germany had received a second vaccination. The 7229 vaccination breakthroughs reported correspond to a share of 0.02 percent. But that doesn’t mean that the vaccines are 99.98 percent effective, see below.
How well do the vaccines protect against corona diseases?
Vaccines reduce the risk of developing corona. The effectiveness of the vaccines is recorded, for example, in approval studies, but can also be monitored and estimated beyond this. To do this, the proportion of fully vaccinated people among Covid-19 cases is compared with the proportion of fully vaccinated people in the population.
According to the RKI, the effectiveness is currently estimated at around 88 percent (age group 18-59) or 87 percent (age group 60+). “The number of vaccination breakthroughs as well as the effectiveness of the vaccines used, estimated according to the screening method, confirm the high effectiveness from the clinical studies,” writes the RKI.
However, the institute also points out possible distortions and data gaps. The number of vaccinated Covid-19 cases is “probably” under-recorded.
Is it surprising that there are vaccination breakthroughs?
No. It was known that there would be vaccination breakthroughs since the results of the approval studies became known. In the final study phase III, for example, the vaccine from Biontech / Pfizer showed an effectiveness of 95 percent against original corona variants. The value says that the likelihood of contracting Covid-19 is 95 percent lower for vaccinated people than for unvaccinated people. However, the effectiveness is not 100 percent. So there were people who became infected and fell ill, despite the high level of effectiveness.
What reasons for vaccination breakthroughs are being discussed?
that not all people benefit equally from the protection of full vaccination. In some groups of people, especially the elderly, the immune system is likely to be less responsive to the vaccine and make fewer antibodies. There are also drugs that inhibit the immune system. It affects people with autoimmune diseases, cancer patients and people who have received an organ donation.
Virus mutations are another influencing factor. The delta variant seems to be able to escape immune protection a little better than earlier variants.
There are also indications that the vaccination protection could decrease over time. Example: Israel. The country had already started a large-scale vaccination campaign at the end of 2020. More recent data from the Israeli Ministry of Health showed that the protective effect among vaccinated people had recently decreased significantly.
Certain risk groups and people aged 60 and over are already receiving booster vaccinations in Israel. This will also be the case in Germany from September: the very old, those in need of care and people with a weakened immune system can then receive another injection. However, the Standing Vaccination Commission (Stiko) has not yet made a recommendation.
How are vaccination rates and vaccination breakthroughs related?
There is also a connection between the vaccination quota and the number of vaccination breakthroughs, which at first appears paradoxical: if the number of people who are vaccinated against corona increases, the number of vaccination breakthroughs also increases. But that does not mean that the vaccines automatically protect less.
What is known about breakthrough vaccination disease severity?
Of the 7229 known vaccine breakthroughs in Germany, 757 patients were admitted to hospital, according to the RKI. This corresponds to a hospitalization rate of almost 10.5 percent. (Mind you: For people who became infected and fell ill despite having been vaccinated completely!) The majority of people who were seriously ill despite having been vaccinated twice were at least 60 years of age or older.
Difficult courses in vaccination breakthroughs develop primarily people with pre-existing illnesses, researchers evaluated the data of 152 patients who were infected with the coronavirus despite having been vaccinated twice and had to be treated in a hospital. The mean age (median) was around 71 years – this means that half of the patients were younger, the other half older.
The vast majority of patients suffered from other illnesses. High blood pressure was observed most frequently (71 percent), followed by diabetes (48 percent), heart failure (27 percent), chronic kidney and lung diseases (24 percent each), cancer (24 percent) and dementia (19 percent). 40 percent of the patients also took drugs that suppressed their immune system.
Only six of the 152 patients were healthy apart from their acute corona disease.
that the mortality rate among fully vaccinated people with breakthroughs is about 50 percent lower than that of unvaccinated people. However, the results of the study have yet to be examined.
Reports of a CDC speech made headlines last week. It was about new findings on the virus variant Delta. It said, among other things, people with Delta vaccine breakthroughs may be just as contagious as those who were not infected. Does that call into question the usefulness of the vaccinations?
No. “The data clearly show that vaccination protects against illness, hospitalization and death from Covid-19,” writes immunologist Carsten Watzl about the lecture
In an outbreak, it was observed that infected people who were vaccinated – i.e. those with breakthroughs in the vaccination – carried just as much virus as those who were not vaccinated. If this is confirmed, vaccinated people who become infected with Delta could possibly pass the virus on in the same way as unvaccinated people, said Watzl. “But those who have been vaccinated are infected less often and of course it still makes a difference whether my counterpart is protected by a vaccination or not.”
One day after the information from the CDC lecture became known, it also appeared that people with breakthroughs in vaccination fight the virus faster and are therefore possibly less contagious. However, the results of the study have not yet been verified by independent experts.
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