Does measuring how much virus there is in a nasal swab help determine how infectious to others they may be? Elizabeth Tracey reports


Shedding virus is the term used to describe the state of being infectious to others, and with Covid-19 there’s a lot about this state we still don’t know. Anna Durbin, an infectious disease expert at Johns Hopkins, says the picture is even more complicated when someone who is vaccinated becomes infected.

Durbin: This is viral load by PCR and we don’t know how much of it is infectious. So that’s my first caveat. We could be measuring dead virus or virus bound to antibody but by and large the more virus you have the more likely you are to transmit, the more likely you are to be symptomatic which can lead to cough and other things that also improve transmission. And generally it could be also that you harbor the virus longer so I think there are several different factors and included in that is behavioral.  :31

Durbin says it is known that people who’ve been vaccinated generally experience less severe cases of Covid-19 but that they can infect others, but how long that period lasts is still being investigated, so for now, masks and physical distancing remain good ideas. At Johns Hopkins, I’m Elizabeth Tracey.