This article provides an overview of the design and methodology of the “Corona lockdown: how fit are you?” (CLOFIT) study, including the questionnaires and scales that were included in the online survey. The aim of the CLOFIT study was to investigate the psychosocial and health consequences of the coronavirus disease 2019 (COVID-19) pandemic in the Netherlands. The survey was conducted among the Dutch population to collect data on immune fitness and the psychological and health consequences of the 2019 coronavirus disease (COVID-19) pandemic lockdown in the Netherlands. The CLOFIT dataset contains measures from N = 1910 participants and is broadly representative of the Dutch general population. The dataset represents both sexes, a range of ages including the elderly, different education levels, and ethnic backgrounds. The cohort also includes people with a diverse health status and range of medication use.

The 2019 coronavirus infectious disease (COVID-19) is caused by infection with the new severe acute respiratory syndrome coronavirus (SARS-CoV-2). Currently, the treatment options for COVID-19 are limited. The purpose of the experiments presented here was to investigate the effectiveness of ketotifen, naproxen and indomethacin, alone or in combination, in reducing SARS-CoV-2 replication. In addition, the cytotoxicity of the drugs was evaluated. The findings showed that the combination of ketotifen with indomethacin (SJP-002C) or naproxen both reduce viral yield. Compared to ketotifen alone (60% inhibition at EC50), an increase in percentage inhibition of SARS-CoV-2 to 79%, 83% and 93% was found when co-administered with 25, 50 and 100 μM indomethacin, respectively. Compared to ketotifen alone, an increase in percentage inhibition of SARS-CoV-2 to 68%, 68% and 92% was found when co-administered with 25, 50 and 100 μM naproxen, respectively. For both drug combinations the observations suggest an additive or synergistic effect, compared to administering the drugs alone. No cytotoxic effects were observed for the administered dosages of ketotifen, naproxen, and indomethacin. Further research is warranted to investigate the efficacy of the combination of ketotifen with indomethacin (SJP-002C) or naproxen in the treatment of SARS-CoV-2 infection in humans.

Pandemic preparedness is an important issue in relation to future pandemics. The two studies described here aimed to identify factors predicting the presence and severity of coronavirus disease 2019 (COVID-19) symptoms. The CLOFIT study comprised an online survey among the Dutch population (n = 1415). Perceived immune fitness before the pandemic (2019) and during the first lockdown period (15 March–11 May 2020) and the number and severity of COVID-19 symptoms were assessed. The COTEST study, conducted between December 2020 and June 2021, replicated the CLOFIT study in n = 925 participants who were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Dutch commercial test locations. The CLOFIT study revealed that immune fitness before the pandemic was the greatest predictor of the number and severity of COVID-19 symptoms (20.1% and 19.8%, respectively). Other significant predictors included immune fitness during the lockdown (5.5% and 7.1%, respectively), and having underlying diseases (0.4% and 0.5%, respectively). In the COTEST study, for those who tested positive for SARS-CoV-2, immune fitness before the pandemic was the single predictor of the number (27.2%) and severity (33.1%) of COVID-19 symptoms during the pandemic. In conclusion, for those who tested positive for SARS-CoV-2, immune fitness before the pandemic was the strongest predictor of the number and severity of COVID-19 symptoms during the pandemic. Therefore, the development of strategies to maintain an adequate immune fitness must be regarded as an essential component of pandemic preparedness.

Purpose The aim of this study was to evaluate whether or not living alone or together throughout the lockdown had an impact on mood, perceived immune fitness, as well as the presence and severity of COVID-19 symptoms. Methods N = 505 participants completed an online survey, which included questions on living situations, as well as mood, perceived immune fitness and COVID-19 symptom presence and severity. These factors were assessed retrospectively for the time periods before and during the COVID-19 pandemic. Results An overall decrease in mood was observed for both those living alone and together during the lockdown period. However, significantly larger increases in feelings of loneliness were observed for the group living alone. Furthermore, both groups reported decreases in perceived immune fitness, whereas only the group living alone reported a significant increase in COVID-19 symptom presence and severity. Moreover, significant correlations were found between perceived immune fitness, anxiety, and loneliness. These correlations were strongest in the group living alone. Lastly, positive correlations were found between perceived immune fitness and mood outcomes with being active, optimistic and the ability to cope with stress. Increased optimism, being more active and the adequate ability to cope with stress were associated with a reduced negative impact on perceived immune fitness. Conclusion The first COVID-19 lockdown period in the Netherlands was a challenging period for both people who lived alone and those living together, resulting in decreases in mood and poorer perceived immune fitness. Those living alone were, however, more heavily impacted by the lockdown restrictions. This was further reflected by the increased presence and severity of COVID-19 symptoms in people who lived alone during the first COVID-19 lockdown in The Netherlands.

Recently, a study was conducted in the Netherlands to evaluate the impact of the coronavirus disease (COVID-19) pandemic and its associated lockdown periods on academic functioning, mood, and health correlates, such as alcohol consumption. The Dutch study revealed that lockdowns were associated with significantly poorer mood and reductions in perceived immune fitness. Overall, a reduction in alcohol consumption during lockdown periods was shown. Academic functioning in terms of self-reported performance was unaffected. However, a significant reduction in interactions with other students and teachers was reported. However, there was considerable variability among students; both increases and reductions in alcohol consumption were reported, as well as both improvements and poorer academic functioning during periods of lockdown. The aim of the current online study was to replicate these findings in Germany. To achieve this, a slightly modified version of the survey was administered among young adults (aged 18 to 35 years old) in Germany. The survey assessed possible changes in self-reported academic functioning, mood, and health correlates, such as smoking and alcohol consumption, perceived immune functioning, and sleep quality during periods of lockdown as compared to periods with no lockdowns. Retrospective assessments were made for five periods, including (1) ‘BP’ (the period before the COVID-19 pandemic), (2) ‘L1’ (the first lockdown period, March–May 2020), (3) ‘NL1’ (the first no-lockdown period, summer 2020), (4) ‘L2’ (the second lockdown, November 2020 to May 2021), and (5) ‘NL2’ (the second no-lockdown period, summer 2021). This article describes the content of the survey and the corresponding dataset. The survey was completed by 371 participants.