Platelets are the major blood component bridging immunity and thrombosis. Abundant in the circulation, platelets encounter pathogens at a higher rate than any circulating leukocyte. Viral particles of various blood-borne pathogens such as HIV,¹ dengue,² or even respiratory viruses such as influenza³ are found inside human platelets. Viral infections with these viruses,⁴ as well as the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), can lead to thrombocytopenia⁵ along with thrombotic complications^6–8 in patients. The presence of internalized viral particles, thrombocytopenia, and thrombosis implicates platelets as active participants in immunity during viral infections.