The currently available kits measure a cocktail of antibodies against several viral Spyke (S) determinants, produced in COVID-19 patients after several days from the infection, and do not selectively discriminate the neutralizing antibodies that are capable to inhibit the infection of human cells, by blocking the interaction between the viral S protein and the human angiotensin-converting enzyme 2 receptor (hACE2). This evidence concerns the gene PROS1 and infection.