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Corona vaccination in Markkleeberg, Saxony
Photo: Jens Schlueter/Getty Images
Anyone who has been vaccinated three times against Corona is initially very effectively protected against becoming seriously ill with Covid-19.
However, this immunity wears off after just three months, as a study in the journal The Lancet Respiratory Medicine suggests.
The work, funded by pharmaceutical company Pfizer, evaluated the effectiveness of the Pfizer/Biontech vaccine against the delta and omicron variants in Southern California.
The research team analyzed data from 11,123 emergency room visits and hospital admissions for an acute respiratory infection between early December 2021 and early February 2022, for which either a positive Sars-CoV-2 test was available or a corona infection was ruled out by testing.
All of the data came from patients who visited a clinic during the study period.
In the case of a corona infection, they differentiated between the omicron and delta variants, partly on the basis of precise virus analyzes and partly simply on the basis of the time of infection, because omicron quickly replaced delta in the USA as well.
In addition to 2838 cases of delta infections, there were 4523 omicron infections, the remaining 3762 cases were patients with an acute respiratory infection that was demonstrably not caused by corona.
5165 were not vaccinated against Covid-19, 3981 were double vaccinated, 1977 were triple vaccinated.
The results initially confirmed what was previously known: that the third vaccination increases protection and that the vaccinations against Delta protect more reliably than against Omicron.
It also shows that the protection weakens after three months, although the amount of data here is so small that the researchers themselves point this out several times in the study.
In the first three months after the third vaccination, the protection against hospitalization because of a delta infection was in the range of 83 to 93 percent, after these three months the effectiveness was only 40 to 86 percent.
Protection against Omicron was similarly high in the first three months at 80 to 89 percent, then subsequently dropped to 28 to 71 percent.
"Covid-19 booster shots with Pfizer/Biontech significantly improve protection against omicrons, although after three months this protection appears to diminish against visits to the emergency room and even against hospitalization," says the study's lead author, epidemiologist Sara Tartof of the Kaiser Permanente Health Consortium , according to the announcement.
In the study, which was financed by the manufacturer as mentioned at the beginning, the team writes that although more data is needed to find out how large this effect actually is, the result suggests that further vaccine doses may be necessary in the future.
The study cannot provide some information, which could, however, distort the result.
Two points: On the one hand, previous corona infections of the participants were only known if they were tested by the clinic operator.
On the other hand, the researchers only analyzed cases in which people went to the hospital because of an acute respiratory infection, but it is still conceivable that some cases were not because of a corona infection, but only in the hospital.
Second booster initially only from 70 and with certain diseases
In Germany, the Standing Vaccination Commission currently recommends a second booster for people over the age of 70 and people with certain previous illnesses.
Federal Health Minister Karl Lauterbach (SPD) recently campaigned in Brussels for a fourth vaccination for everyone over 60 years of age.
At the beginning of April, the EU drug authority Ema declared that a fourth dose for all citizens is currently not necessary.
However, it could be useful for people aged 80 and over given the higher risk of severe Covid 19 disease.
On the other hand, experts recently confirmed in a video link that young, healthy people do not need a second booster vaccination: The drop in antibody levels after an infection or vaccination is “a completely normal process,” said the scientific director of the German Rheumatism Research Center Berlin, Andreas broken wheel.
There is then less mass, but the quality of the antibodies increases - "and quite drastically".
This very important process, the so-called affinity maturation, lasts about half a year and cannot be shortened: Against this background, anyone who is now considering a second booster can “wait until autumn” so as not to interrupt this process.
wbr/dpa