Scientists have identified four types of reactions to COVID-19 vaccines and a risk group
Kyiv • UNN
Japanese scientists have identified four types of the body's reaction to COVID-19 vaccines using artificial intelligence. The study showed that people with high initial antibody levels that rapidly decline are at the highest risk of infection.
Scientists have identified four types of body reactions to COVID-19 vaccines and identified the group at highest risk of infection. This is reported by Medical Xpress, writes UNN.
Details
The new study was published in the journal Science Translational Medicine.
At Nagoya University in Japan, 2526 vaccinated individuals were observed for 18 months. Using artificial intelligence, researchers developed a mathematical system to classify immune responses and, for the first time, systematically identified a group with a "rapid decline."
Researchers found that the immune response can be divided into four distinct types:
- some people maintained high antibody levels for a long time (sustained responders);
- in others, it started high but quickly declined (rapid decline responders);
- a third group produced few antibodies, the level of which also rapidly decreased (vulnerable responders);
- and others showed an intermediate state (intermediate responders).
According to the head of the study, Professor Shingo Iwami, the results for the "rapid decline" group were unexpected.
Despite an impressive initial immune response, they (the rapid decline group - ed.) contracted COVID-19 faster than other groups, while those with a sustained immune response remained protected for longer. Single blood tests for IgG antibodies, the type of antibodies we used for classification, could not detect this risk. Only by tracking changes over months did we see a pattern.
As reported, people in the group who initially had the highest antibody levels, but whose levels declined faster, became infected earlier. People with lower levels of IgA(S) antibodies in their blood, which protect the nose and throat, were also at higher risk. The results show that monitoring changes in antibody levels over time can help identify people at increased risk of infection.
Overall, after revaccination, 29% of participants were in the sustained response group, 28% in the vulnerable category, 19% in the rapid decline group, and the rest showed intermediate results. At the same time, the frequency of breakthrough infections ranged from 5.2% among sustained responders to 6% among vulnerable and "rapidly declining" individuals.
For the first time, we were able to clearly group people by their response to COVID-19 vaccines. Identifying the pattern of rapid decline is particularly important - it helps explain why some people may need revaccination earlier than others.
He also added that this could potentially contribute to better, more personalized vaccination strategies. However, whether antibody testing can be widely used depends on cost, accuracy, and whether the benefits are worthwhile compared to current strategies. Further research is needed.
Recall
In September, the number of COVID-19 cases in Ukraine is increasing; 10,622 cases were recorded in the 35th week of 2025. Local authorities are making decisions on anti-epidemic measures, including mask mandates.
Last week, Ukraine registered 14,926 cases of COVID-19, which is 3.5% more than the previous week. 19 deaths were recorded, with fewer cases in the four weeks of 2025 than in the same period last year.