Covid-19 is still having a devastating effect on many countries and economies worldwide and has brought to light the impact of diseases that affect some people in worse ways than others. With SARS-CoV-2, ethnicity, gender, age, and underlying health conditions all play a part in disease severity and mortality, but there is mounting evidence to suggest that the status of the immune system early after infection can be predictive of those who go on to have the worst symptoms. The scale and threat of the pandemic has led to the need for rapid analysis of the disease – because the better we understand it, the more easily we can help healthcare professionals to make critical personalised treatment decisions. Advanced technologies such as artificial intelligence and machine learning are playing a large role in this process, and with other diseases, too, accelerating scientific research to enable major breakthroughs.