Frankfurt Not only a lack of willingness to vaccinate, but also the declining effect of the leading Covid vaccines is likely to play a significant role in the current increase in infection rates.
Infection data as well as various analyzes and clinical studies mean that the protective effect of the vaccine decreases significantly over time, with considerable differences between the individual vaccines becoming apparent.
Overall, the pressure for booster vaccinations continues to increase. Experts from the vaccine manufacturers meanwhile do not rule out that such booster vaccinations could be necessary on an annual basis.
On the one hand, there is the general infection rate: a number of countries continue to have high and in some cases rising infection rates despite high vaccination rates. In Germany, for example, the number of people actively infected is currently 205,000, a third above the previous year’s level. At around 355,000 in the last 30 days, the number of new infections is around 50 percent higher than in October 2020, the number of covid-associated deaths was around 2100, around twice as high as in the same period of the previous year.
In contrast, the number of intensive care patients, currently around 1,800, is still slightly below the previous year’s figure. This corresponds to a share of almost 0.9 percent of all currently infected, compared to 1.23 percent a year ago. It will now be interesting to see how the numbers develop over the next few months. Last autumn, the proportion of intensive care patients in the total number of Covid infected people rose from 1.2 to 2.3 percent from the end of October to February.
Vaccination breakthroughs are increasing
The number of vaccination breakthroughs, i.e. the number of symptomatic Covid infections in fully vaccinated people, has so far been limited overall, but is increasing significantly. Of the almost 1.1 million symptomatic Covid cases since the fifth calendar week, i.e. since the completion of the first complete vaccinations, according to the latest data from the RKI, almost eleven percent were fully vaccinated.
In the last four weeks alone, however, the proportion was around 36 percent. In people over 60 years of age, who tended to be vaccinated earlier than younger people, 59 percent of the new cases of infection were recently in those who were fully vaccinated.
The trend for hospitalizations and deaths is similar. Overall, only around eight percent of hospital treatments and covid-related deaths have been due to breakthroughs since the beginning of February. In the last four weeks alone, the proportion of vaccine breakthroughs in deaths was around 40 percent and in the age group over 60 years even 45 percent.
The increase is partly due to the fact that the proportion of people who have been vaccinated has risen continuously over the past few months. In addition, a weakening effect of the vaccines is likely to play a role. The RKI estimates the effectiveness of the vaccine for the last four weeks at 75 percent for 18 to 59 year olds and 73 percent for people aged 60 and over as high.
At the beginning of September, however, the institute had rated the effectiveness about ten percentage points higher. The protective effect against intensive treatments then decreased from 94 to 91 percent in those over 60 years of age.
The moderna vaccine tends to keep its effectiveness longer and better than the vaccines from Biontech, Astra-Zeneca and Johnson & Johnson (see graphic)
Clinical studies
In the meantime, several clinical studies have also given a clear indication of the diminishing effectiveness of the vaccine. In September, Moderna published comparative data of two groups who were vaccinated in July to October compared to the study participants who had originally received placebo and who were only subsequently vaccinated from December to March 2021.
There were 88 breakthrough infections in the group vaccinated more recently, compared to 162 in the group vaccinated between July and October. According to Moderna, a ratio of 49 to 77 cases is calculated per 1000 person-years. The incidence in the group vaccinated later was thus 36 percent lower in the group that was vaccinated earlier.
An even clearer indication of a decreasing effect emerges from the data that Biontech and Pfizer presented a few days ago for their study with a booster vaccination.
This included around 10,000 people who had been vaccinated twice on average around eleven months earlier. Half received a third vaccination with the standard dose of 30 micrograms mRNA vaccine.
In the observation period of two and a half months from one week after this booster vaccination, according to Biontech, only five cases of infection occurred in the group of those additionally vaccinated, compared to 109 in the group that was only vaccinated twice.
However, this also means that the infection rate for people who have only been vaccinated twice – with 109 cases in around 5,000 participants – in the period from eleven months after the vaccination is apparently much higher than in the first months after the vaccination.
In the primary clinical study, the results of which Biontech and Pfizer presented a year ago, only eight infections occurred in a good 18,000 people who had been vaccinated during the observation period of up to three and a half months after the second vaccination.
The infection rate now observed in the booster study in those who were only twice vaccinated corresponds to a weekly incidence of around 220 infections per 100,000 people and is thus almost at the level of the general infection rate in the USA, where the study was mainly carried out.
Real-world analysis
A number of real-world analyzes also clearly indicate a trend towards decreasing effectiveness. A study from Israel published a few days ago in the New England Journal of Medicine (NEJM) came to the conclusion that a few months after the vaccination, the immune protection against the delta variant decreased in all age groups. The analysis included data from 4.8 million people vaccinated with Biontech and all cases of infection registered between July 11 and 31.
The infection rate in people who were vaccinated in January was three to four times higher than in people who received their vaccination in May, depending on the age group. According to the study’s authors, there is a clear increase in infection rates depending on the time interval between vaccination.
The rate of serious Covid illnesses in those over 60 was 0.12 cases per 1,000 people who were vaccinated in May, compared to 0.34 cases per 1,000 people who had received their vaccination four months earlier. Real-world analyzes from the USA and Great Britain had previously shown similar results.
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