Re: Covid-19: Why Germany’s case fatality rate seems so low: Is nutrition another possibility
We read with interest the Global Health feature “Covid-19: Why German case fatality seems so low” as compared to most of the other European countries (1). The author proposed several explanations including an early and large testing of the population. Most current debates focus on the differences among countries, but little attention has been given to regional differences.
We used Worldometer to assess death rates as this tool provides detailed information on deaths at the regional level (https://www.worldometers.info/coronavirus/country/germany/). The current death rate per million people in Europe shows different trends. Germany has a low death rate (48 deaths, April 17, 2020), but Austria (46), the Czech Republic (18), Poland (8), Slovakia (1), the Baltic States (from 2 to 27) and Finland (14) have similar or lower rates. On the other hand, Belgium (479), France (275), Italy (367), Spain (423) and the UK (202) have far higher rates. The low-rate countries have used different quarantine and/or confinement methods and none have performed as many early tests as Germany. Thus, although the German approach is very important, other factors may also be significant.
Large differences exist when assessing death rates within a country. In Germany, Bavaria started the earliest tests but was and still is the most affected region. Death rates per million range from 8 in Mecklenburg-Vorpommern to 87 in Bavaria. In Switzerland, the French and Italian speaking cantons have a far higher death rate than the German-speaking ones (Office fédéral de la santé publique, Switzerland, https://www.bag.admin.ch/bag/fr/home.html). In high-rate countries such as Spain, large variations also exist within the country, but the numbers range from 50 in Ceuta to over 1,000 in Madrid.
Most diseases exhibit large geographical variations which frequently remain unexplained despite abundant research (2). Covid-19 will not be an exception. Though the more relevant factors are likely to be seasonal variations, the immunity, cross-immunity and the intensity and timing of measures (3), other factors like environment or nutrition should not be overlooked.
Germany, Austria, the Czech Republic, Poland, Slovakia, the Baltic States and German-speaking Swiss cantons exhibit lower Covid-19 mortality rates than France, Italy, Spain, and the French and Italian speaking Swiss cantons. Obesity, a risk factor of mortality in Covid-19, suggests the importance of nutrition. Diet differs considerably between low or high mortality countries. Nutrition may therefore play a role in the immune defense against Covid-19 and may explain some differences seen in Covid-19 across Europe. A Mediterranean diet more common in Italy, France and Spain does not appear to be protective. Foods with potent antioxidant or anti angiotensin-converting enzyme activity - like uncooked or fermented cabbage (4-6) - are largely consumed in countries like the low death rate European countries, Korea and Taiwan, and might be considered in the low prevalence of deaths.
Understanding the within and between country differences in Covid-19 will be of paramount importance in understanding Covid-19 risk and protective factors, and will eventually help to control the epidemics.
Jean Bousquet, MD, Charité, Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Comprehensive Allergy Center, Department of Dermatology and Allergy, Berlin, Germany and MACVIA-France, Montpellier, France
Wienia Czarlewski, MD, Medical Consulting Czarlewski, Levallois, and MASK-air, Montpellier France
Hubert Blain, MD, Pole Gérontologie, University Hospital, Montpellier University, MUSE, Montpellier
Torsten Zuberbier, MD, Charité, Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Comprehensive Allergy Center, Department of Dermatology and Allergy, Berlin, Germany
Josep M Anto, MD, ISGlobAL, Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain. Universitat Pompeu Fabra (UPF), Barcelona, Spain and CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
None of the authors have any conflict of interest to declare
1. Stafford N. Covid-19: Why Germany's case fatality rate seems so low. BMJ. 2020;369:m1395.
2. Sunyer J, Jarvis D, Pekkanen J, Chinn S, Janson C, Leynaert B, et al. Geographic variations in the effect of atopy on asthma in the European Community Respiratory Health Study. J Allergy Clin Immunol. 2004;114(5):1033-9.
3. Kissler SM, Tedijanto C, Goldstein E, Grad YH, Lipsitch M. Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period. Science. 2020.
4. Dang Y, Zhou T, Hao L, Cao J, Sun Y, Pan D. In Vitro and in Vivo Studies on the Angiotensin-Converting Enzyme Inhibitory Activity Peptides Isolated from Broccoli Protein Hydrolysate. J Agric Food Chem. 2019;67(24):6757-64.
5. Gharehbeglou P, Jafari SM. Antioxidant Components of Brassica Vegetables Including Turnip and the Influence of Processing and Storage on their Anti-oxidative Properties. Curr Med Chem. 2019;26(24):4559-72.
6. Patra JK, Das G, Paramithiotis S, Shin HS. Kimchi and Other Widely Consumed Traditional Fermented Foods of Korea: A Review. Front Microbiol. 2016;7:1493.
Competing interests: No competing interests