Pandemic Preparedness: The Importance of Adequate Immune Fitness

Abstract

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.

Keywords: COVID-19; SARS-CoV-2; age; immune fitness; pandemic preparedness; sex; underlying disease.

Figure 1

Relationship between immune fitness and the number and severity of COVID-19 symptoms for participants that tested positive for SARS-CoV-2. Shown is the relationship between the number of COVID-19 symptoms and immune fitness (2019) (A) and immune when tested for SARS-CoV-2 (B), and the relationship between the severity of COVID-19 symptoms and immune fitness (2019) (C) and immune fitness when tested for SARS-CoV-2 (D). The red lines represent the Spearman’s correlations. Correlations are considered significant if p < 0.05. Abbreviations: COVID-19 = coronavirus disease 2019; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2.