COVID-19 presentation varies widely between individuals, ranging from asymptomatic to life-threatening infection. Several host and viral factors have been shown to influence disease penetrance and severity. In addition, the infectious dose has also been speculated to have a role. Dabisch et al. show in a SARS-CoV-2 challenge study of 16 cynomolgus macaques that the infectious dose indeed influences symptom development and seroconversion. They used aerosolized virus at different concentrations and found that low doses could lead to seroconversion and virus replication in the respiratory tract without symptom development, such as fever, whereas higher doses produced fever, which suggest that low infectious doses might be associated with asymptomatic infection.