Several people have asked about the risk haplotype in the post below. If you have been genotyped on Ancestry, 23andMe, and Family Tree DNA (unless you are on 23andMe after summer of 2017) there is one SNP in high LD with the causal variant you can look up. It’s rs10490770. The risk allele is C and non-risk allele T. If you download the raw data from any of these services you can find rs10490770 with a search, and look for your genotype (if by some chance it is a reverse strand, the risk allele may actually be G and the non-risk allele A).
What does risk vs. non-risk mean? You can read the original paper, Genomewide Association Study of Severe Covid-19 with Respiratory Failure. They say: “We identified a 3p21.31 gene cluster as a genetic susceptibility locus in patients with Covid-19 with respiratory failure and confirmed a potential involvement of the ABO blood-group system…”
It looks like in their sample CT = 1.75 times greater chance of severe respiratory problems, and CC = 3 times greater chance. The frequency is ~10% or less in Western Europeans, so very few people are CC (~1%). But in South Asians the risk allele is 30-40%, which means that 10-15% of people have the CC genotype!