Are some covid-19 positive patients truly asymptomatic? Were the asymptomatic patients tested by nose swab or PCR? PCR testing showing fragments of the virus does not necessarily indicate the patient is currently transmitting the virus, because transmission requires the virus be enclosed in a membrane. Fragments of the virus may indicate past infection, and can be a sign of immunity. It is unclear if a positive PCR test in an asymptomatic person proves the person can transmit covid-19 to others.
Any of the following may be true: the covid-19 patient was truly asymptomatic; the patient had symptoms and assumed it was nothing, allergies or some other medical problem, like bad food, and recovered; the patient was previously symptomatic but did not recall the illness or did not relate the prior illness to the positive test; the patient was recently ill with another related virus that provided cross-reactivity and full or partial protection from covid-19; the patient took medications for other reasons that helped protect against the virus; the patient was vaccinated against other pathogens and the vaccination provided full or partial protection; the patient was pre-symptomatic and became symptomatic days later.
Obtaining a more detailed history from asymptomatic or mildly symptomatic patients, including the type of testing done; and a history of any prior illnesses, vaccinations, medications taken for chronic illness, and any medications taken for prior acute illnesses or symptoms, may help us understand why some patients have mild or no symptoms, and aid in the fight against covid-19.
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