A new study warns that around 40–45% of people who contract SARS-CoV-2 most likely remain symptom-free. Such cases may contribute to the “silent spread” of the virus. Moreover, even asymptomatic people may experience long-term respiratory issues, the study authors caution. In considering the spread dynamics of the new coronavirus — or SARS-CoV-2 — researchers, and health authorities have been pondering the importance of “silent” transmission. This concept says that people who may have contracted the virus but who do not experience any symptoms could unwittingly contribute to the spread by not realizing they are carriers. It remains unclear just what the likelihood is of asymptomatic transmission. Recently, Dr. Maria Van Kerkhove, Head of Emerging Diseases and Zoonosis at the World Health Organization (WHO), said that this form of transmission was “rare,” though later, she and her colleagues revised that statement in a Q&A session. Now, a new study from the Scripps Research Translational Institute in La Jolla, CA, emphasizes just how many cases of SARS-CoV-2 infection are asymptomatic. Another issue that the researchers draw attention to in their review is the impact of the new coronavirus on the health of asymptomatic individuals. Looking at CT scan results for a cohort of 76 asymptomatic individuals who were present on the Diamond Princess cruise ship, they found that 54% of these individuals presented subclinical lung abnormalities. In their paper, the authors qualify this finding as “disturbing,” as it suggests that even in those who experience no symptoms of infection, the new coronavirus may be causing harm, possibly affecting normal lung function.