Thank you for your question! We are looking into it to answer. If anyone of the forum users is familiar with this topic, please share your knowledge. 

Trying to answer to your question, we can say that genetic epidemiology has made important contributions to medicine and public health. In your question, you mentioned "diseases related to COVID-19". In fact, COVID-19 is a respiratory illness caused by the new virus named SARS-CoV-2.

I have found these information on the topic at the following sources:

https://www.researchgate.net/publication/340394888_Genomic_Epidemiology_and_its_importance_in_the_study_of_the_COVID-19_pandemic

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7117787/

https://www.who.int/news-room/q-a-detail/q-a-coronaviruses

Ten Greek universities and research centres have started a new epidemiological research programme to trace the evolution of COVID-19 across the country. The researchers will look into extensive testing for the virus, antibody detection, viral genome sequencing, and analysis of the host genetics of coronavirus patients. The aim is to understand what makes some people more susceptible to developing severe symptoms. https://www.greeknewsagenda.gr/index.php/topics/business-r-d/7207-greek-scientific-and-research-community-join-forces-to-combat-covid-19