November 10, 2026, 7:01 pm | Read time: 6 minutes
The COVID-19 pandemic is “over.” Yet, for many people, the immense stress they felt back then still lingers. Those were years filled with worries, sometimes sheer fear, marked by isolation and restrictions whose extent is hard to imagine today. Such stress likely doesn’t pass without a trace. It’s hardly surprising, then, that this has apparently manifested on a biological level, as the results of a new German long-term study show. According to the study, certain biological aging processes accelerated during the pandemic in both children and adolescents as well as adults, with the connections being particularly noticeable in one of the groups.
That COVID-19 illnesses can affect physical condition has already been studied. FITBOOK reported in 2021 on several studies suggesting that the fitness of even relatively young people can drop to a level more typical of seniors following an infection.1
But even without an infection, the pandemic posed a significant psychological burden for many people, the authors of the current study write in their introduction.2 Psychosocial stress is considered a major risk factor for various age-related diseases. Previous studies also suggested that social isolation and psychological stress can be linked to accelerated biological aging.3
Details of the Study
The researchers explored whether the pandemic could have influenced biological aging processes. They were also interested in the possible impact of perceived stress, external pandemic conditions, and pre-existing health risk factors.
The study was a prospective longitudinal study. Participants were examined at multiple points in time to capture and compare individual changes over a longer period.
The data was based on the “TwinLife Epigenetic Change Satellite” (TECS) subproject of the German TwinLife project, a long-term study with twin families to research social inequality.4,5 The subproject examined, among other things, epigenetic changes related to the COVID-19 pandemic.
Saliva Sampling at the Start and During the Pandemic
A total of 1,028 participants were included in the analysis, including 359 children, 385 adolescents, and 284 adults. Saliva samples were taken from all of them before the first COVID-19 containment measures in Germany—that is, before March 2020. At this first examination, the average age of the children was 9.51 years, the adolescents were 15.47 years old, and the adults had an average age of 24.28 years. A second sample collection took place between September 2021 and May 2022. There was a time gap of 1.5 to 3 years between the measurements.
The researchers examined the saliva samples for DNA methylation, which refers to chemical markings on DNA that can influence the activity of certain genes without changing the DNA sequence itself. Four different epigenetic clocks were used: Horvath, PedBE, GrimAge2, and DunedinPACE. The first three measure the epigenetic age and its deviation from chronological age. DunedinPACE, on the other hand, measures the speed of biological aging processes, with a value of 1 representing an aging rate that corresponds to the chronological aging process.
External Stress Factors Considered
The researchers also considered objective stress factors in their analysis, including regional infection rates and the severity of government restrictions. Subjective factors such as personal feelings of threat and perceived pandemic stress were also included, as well as the general physical health of the participants, any psychological issues, and socioeconomic characteristics.
For statistical analysis, the researchers used linear mixed models. These took into account repeated measurements and the familial or genetic relationships of the participants.
Results: COVID-19 Accelerated Biological Aging
During the pandemic, three of the four examined epigenetic aging markers significantly increased, the study showed. Three of the four measurement methods (PedBE, GrimAge2, and DunedinPACE) indicated accelerated biological aging, while the fourth method showed no statistically significant change.
This result was evident in the combined analysis of all participants. The observations held even after the researchers accounted for potential influencing factors such as the participants’ body mass index (BMI) and reported smoking exposure.
However, differences were observed between the various age groups. For children, only one value significantly increased. Adolescents showed signs of accelerated biological aging in three of the four measurement methods. For adults, this was only detectable in two of the methods.
Key Influences: Subjective Stress and Predispositions
The authors found a particular connection among adolescents between the subjective stress felt during the pandemic—such as separation from important contacts and restrictions on personal freedoms—and biological aging. The more intense the stress was perceived during the third lockdown, the more pronounced the increase in measured aging speed was in this group of participants.
Physical health factors were also linked to the measured changes in aging markers. For instance, increased smoking exposure was associated with greater changes in biological aging markers. The same was true for a higher body mass index (BMI) and certain DNA-based markers that indicate a molecular predisposition to obesity. Additionally, the socioeconomic status of the parents played a role: The lower it was, the more the biological aging processes accelerated in the affected adolescents.
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Significance of the Results
Extraordinary societal stresses like the COVID-19 pandemic can apparently be associated with measurable changes in biological aging processes. This is what the researchers conclude from their observations. The study’s results also emphasize that biological aging is linked to various physical and psychosocial factors.
The findings are remarkable and potentially relevant for health research, as the authors explain. Epigenetic clocks could help make early biological changes visible, ideally before any potential health consequences appear.
However, it is still unclear whether the observed “COVID-19 changes” will have long-term health consequences. The study also cannot answer whether they can be reversed through certain lifestyle measures.
Limitations
In general, the study cannot prove a causal link between COVID-19 and accelerated biological aging. Among other things, the study lacked a comparable control group that was examined during the same period without the societal changes of the pandemic.
Another limitation is that the sample consisted mainly of young and healthy individuals. Therefore, the results cannot be easily generalized to other population groups. Additionally, only samples from two measurement points were available, so the researchers could not capture fluctuations or nonlinear changes in aging.
Regarding the measurement methods themselves, it should be noted that the epigenetic clocks used differ in their calculation and sensitivity to environmental influences. GrimAge2 and DunedinPACE, for example, were originally developed with blood samples from adults, but the study examined saliva samples from children and adolescents as well. In the future, age- and tissue-specific methods might provide more accurate results.
Furthermore, the assessment of pandemic stress was rather limited. Especially since the subjective stress experienced depends on individual factors, such as mental health and social environment. Neither regional infection rates nor government restrictions showed a consistent connection with the biological changes.
The results remained consistent even after households with a reported COVID-19 infection were excluded from the analysis. Nevertheless, the authors cannot completely rule out a possible influence of viral infections on the results.