Since the emergence of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) in Wuhan in December 2019 and the global spread of the virus, the pandemic has greatly changed daily lives and social participation (1–3). To minimize new infections, all social events and contacts outside the household were restricted. The German population was asked to practice social distancing, to observe hygiene regulations and to wear a mask. There were several “lockdowns” in Germany, the first starting 22nd March 2020 for 3 weeks and the last one from 16th December 2020 for about 4 weeks (4). The population subsequently spent a larger part of the day at home with less contact to others (1). The above-mentioned circumstances could have a negative impact on social participation, which in turn is negatively associated with health status and quality of life (5, 6).

The impact of COVID-19 related lockdowns on lifestyle habits and behavioral risk factors cannot be ignored. Immunocompromised individuals as a vulnerable population are particularly at risk for severe COVID-19 and therefore also at a higher risk for psychological distress (7). Also non-pharmacological treatments for mental disorder such as enhancing exercise were restricted during the pandemic (8, 9). Nürnberger et al. reported that immunocompromised individuals as well as women in general have a high level of COVID-19 anxiety (10). For this reason, it is likely that these individuals follow measures more diligently compared to non-immunocompromised individuals or they take additional infection prevention measures even beyond the official requirements. Additionally, family and friends of such persons could be more careful in keeping their distance to avoid the risk of infecting vulnerable loved ones.

Stipulating infection prevention measures that require individuals to reduce social contacts create a difficult tradeoff between physical and mental health. Initial studies confirm this psychological burden (11, 12).

The COVID-19 vaccination is considered the most effective protective measure to prevent severe courses of COVID-19. Recommendations on the number and timing of vaccine doses changed frequently during the pandemic. At the beginning of our study, it was assumed that a basic vaccination was achieved 14 days after the second vaccination. All in Germany licensed COVID-19 vaccines are highly effective in protection against severe and lethal COVID-19 (13–16). At the time of the first vaccinations in 2021, it was assumed that social restrictions could be eased after achieving a high vaccination rate about 80% (17). Today, even higher vaccination rates and booster vaccinations are known to be necessary in presence of highly infective and partly immune-escape SARS-CoV-2 virus variants (18).

Vaccine efficacy in immunosuppressed people remains unclear (19, 20). Due to the new virus variants of concern, vaccine effectiveness has decreased even for immunocompetent persons, in particular against infection and any COVID-19 disease, whilst effectiveness against severe disease remains high (21, 22). Factors influencing social participation could be the number and type of immunosuppressive medications and comorbidities as well as self-perceived vulnerability for a severe COVID-19 course. Due to viral variants of concern, the difficult predictability of the individual case and studies with only small numbers of investigated cases, the vaccine effectiveness for immunocompromised persons remains not entirely clear. Nevertheless, vaccination status may change the perceived importance of safety behaviors and decrease the compliance with measures to limit the spread of the disease. Social participation could increase because of a sense of security, even though the actual level of protection remains uncertain.

Understanding the impact of vaccination on social participation and mental health during the pandemic period will lead to increased understanding of the impact of infection prevention measures upon everyday life and health. This knowledge can be used when planning further measures.

The main hypotheses tested in this study are:

The first participant was included on March 28, 2021. The last participant was included in May 20, 2021. No participant completed the survey during the period of national lockdown in Germany.

After applying the in- and exclusion criteria, 126 participants were included in the final analysis (see Figure 1). The mean difference between T0 and T1 was 81.6 days (SD: 22.5) and between T0 and T2, 236.5 days (SD: 27.7).

This study focuses on the change in social participation between three time points before a basic COVID-19 vaccination to 6 months after vaccination. About 60% of our participants had an increased social participation (i.e., experienced fewer limitations to social participation) at median about 10 IMET points and 40% had a decreased social participation 6 months after basic COVID-19 vaccination. Sociodemographic and medical factors (except hypertension) did not differ between these two subgroups. The results of this study support the hypothesis that a basic vaccination is associated with increased social participation. The reduction of limitations to social participation may motivate individuals to get vaccinated and consequently increase the vaccination rate. Between 1 and 6 months after the basic vaccination, the level of social participation remains stable. The domains “recreation and leisure,” “social activities,” and “close personal relationships” were mainly responsible for the reduction of limitations to social participation, whereby “social activities” was the area where limitations decreased most.

The courses of social participation were different within 6 months of basic vaccination. More than the half of the participants had a heterogeneous course. About one-fifth of the participants showed an increase of social participation over all three time points. Nearly one-quarter of all participants reported more limitations 1 month after a full vaccination and fewer limitations 5 months later. With regards to this up and down profile, it is important to note that the actual protection provided by the COVID-19 vaccination is still unclear for immunocompromised individuals in general and even more so on an individual level. A possible explanation for the reduction of limitations at T2 is the fact that participants of the CoCo immune study could see the results of their T1 antibody-test online about 4 weeks after T1. Therefore, at T2, the participants knew if they had developed antibodies against SARS-CoV-2. This may have decreased their sense of vulnerability and improved their social participation–although the study personnel emphasized that the development of antibodies is not synonymous with protection and all participants were advised to continue to observe safety measures. There was no association between social participation and a third vaccination, local COVID-19 incidence rates, or mental health. Those participants whose social participation levels were worse compared to pre-pandemic norm values before a basic COVID-19-vaccination improved more frequently than those whose social participation was better or at the norm.

Most studies investigating social participation among certain COVID-19 risk groups did so in a cross-sectional design at one time point (33–35). Mergel and Schützwohl also observed increased impairments in social participation by using the IMET questionnaire during the first year of the COVID-19 pandemic, when no COVID-19 vaccination was available (25). The median amount of change (10 points) is similar to the change in social participation in a study which investigated the impact of a rehabilitation on the social participation of people with chronic inflammatory bowel diseases (26).

This study did not indicate an association between the change in social participation and several sociodemographic factors. In other studies, the elderly are often described as a vulnerable group with less social participation and less mental health during the pandemic (36, 37). In our study, there was no significant impact of age on the change in social participation. This may be explained by the fact that this study only examined the changes of social participation and did not consider the baseline social participation level. Age-related differences may be masked by immunosuppressive medication, as a greater impact of this on social participation is possible.

Gender influenced participation in work life during the COVID-19-pandemic according to Flor et al. Women were more often affected by losing their jobs or dropping out of school (38). Another study found that living in small villages is negatively associated with social participation (39). These findings were not confirmed by our study of participants with a severe chronic illness and immunosuppressive treatment.

Hypertension was the only comorbidity that had a significant influence on the change in social participation. Participants with hypertension were more likely to experience more limitations to their social participation. Deng et al. observed that participants with hypertension had a nearly 4.5-fold higher risk of death when infected with SARS-CoV-2. It seems possible that participants with hypertension have a greater fear of a severe COVID-19 course and therefore restrict themselves to an above-average extent (40). However, the impact of hypertension on social participation or potential confounders need to be investigated further.

Our results do not prove the assumption that mental health is related with changes in social participation. In contrast to our findings, higher incidence rates of depressive symptoms were observed in older people with less social participation during the COVID-19 pandemic by Noguchi et al. (36). This difference can be explained by different participant groups and study settings. Other studies investigated the anxiety and depression levels at one timepoint after a COVID-19 vaccination that improved already after one vaccination dose (41).

Changes in social participation were not correlated to changes in COVID-19 incidence rates. One explanation for this lack of a pandemic-related effect could be that over the course of the pandemic, people got more familiar with digital communication and an accustomed to the pandemic realities (42). Becoming accustomed to the pandemic influences wellbeing and social participation as well (43). The temporary mitigation of the restrictions during the study period could have enabled participants to improve their social participation. Infections with the omicron variant lead to less severe courses of illness and less hospitalizations compared to earlier variants, and in general there were less severe or fatal cases than in the earlier days of the pandemic. Likely due to increasing vaccination levels. Therefore, the threat of a severe COVID-19 course during the omicron phase of the pandemic was likely perceived as lower than in the earlier measurements (44, 45). A common “pandemic fatigue” or getting more used to the situation could have influenced results at the follow-up timepoints.

The COVID-19-vaccination effectiveness in immunocompromised people depends on the underlying condition, immunosuppressant medication, and general health and is therefore variable (46). The currently prevailing omicron variant is less severe but still worrying and a threat to all individuals, especially for immunocompromised people. Loosening safety measures exposes to a high risk of infection (47).

This study has several limitations. Out of 272 recruited participants 126 were included in the final analysis. Due to the recruitment strategy and the loss-to-follow-up the sample of this study is not representative for all immunocompromised people in Germany. We were unable to reach all study participants in our telephone follow-up to gather the information about the third vaccine dose. Also, our sample was recruited as a non-random convenience sample which could lead to a selection bias. However, the CoCo Immune Study represents a true-to-life cross-section of primary care reality.

There is no control group of immunosuppressed individuals who refused COVID vaccination, nor a healthy control group. Such a control group would increase the validity of our results regarding the influence of the COVID-19 vaccination on social participation in immunocompromised people and helped to differentiate disease specific effects from generic phenomena. However, our ethics committee advised against requesting people at high risk for a severe COVID-19 course to stay unvaccinated for 6 months due to the health risks for both participants themselves and others. Sociodemographic and disease-related factors were collected only with the baseline questionnaire. Therefore, the underlying different chronic diseases of the participants may have worsened over the study due to normal chronic disease progression.

There are several factors beside the COVID-19 vaccination that could have confounded our results. The pandemic situation with its measures and restrictions is very quickly changing. The incidence rates of one county may not be sufficiently correlated to the whole pandemic situation. Since the participants’ exact place of residence is unknown due to data protection measures, it was impossible to pinpoint the exact local COVID incidence rate for each participants’ residential community. Even so, this study is located in the county of Göttingen and most participants come from the greater Göttingen region. The incidence rates in Göttingen, which were similar to the overall incidence rates in Germany though on a usually somewhat lower level. Limitations to social participation could be influenced by changing seasons. Colder outdoor temperatures lead to a higher incidence of contagious diseases other than COVID-19, for which immunosuppressive people are at a high risk. Therefore, perceived social participation could be influenced by the observational timepoint in our study. Due to the long duration of this study, this bias could be minimized. The IMET scale reflects the participants’ perceived impairments and not their actual social activities (i.e., how limited the participant feels but not the number of social interactions themselves). The questionnaire was not developed to reflect social participation during a pandemic situation. An improved questionnaire which takes particular pandemic situations into account may lead to more valid results.

One month after basic COVID-19 vaccination, social participation increased and then stayed stable for the next 5 months. Social activities, recreation and leisure, and close personal relationships were mainly responsible for changes in social participation following COVID-19 vaccination. Our sample shows a high variability between the individual participants. The protection expected of a COVID-19 vaccination is likely to have increased social participation levels. On the one hand, individual vaccine effectiveness in this particular group is quite unpredictable, and increased social participation comes with a higher risk of infection for immunocompromised individuals, for example, due to less safety behavior. On the other hand, improved social participation may be a convincing argument to motivate immunocompromised people to get vaccinated. These results highlight the heterogeneity of changes in social participation in a homogeneous group during a similar time period. In addition, other factors that might influence social participation need to be investigated in order to target vulnerable groups and plan interventions. Therefore, studies with larger sample sizes or qualitative studies might be useful.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by the Institutional Review Board of Hannover Medical School (9948_BO_K_2021) and University Medical Center Göttingen (29/3/21). The patients/participants provided their written informed consent to participate in this study.

GH and FM: conceptualization. DS and GH: methodology and writing – original draft preparation. DS: formal analysis and visualization. GH, SH, and FM: investigation. SH, FM, MM, EH, FK, JN, KV, and MM: writing – review and editing. FM, SH, and EH: funding acquisition. All authors have read and agreed to the published version of the manuscript.