Recovered patients can become infected again?

Hi all,

I recently saw a video interviewing Dr. Kim Woo-Joo, an infectious disease specialist at Korea University. In the interview, the doctor mentions that there some cases where recovered patients become “re-activated” or infected again. Note, I don’t have any numbers, and it may be a small percentage

The title of the video is " You Need To Listen To This Leading COVID-19 Expert From South Korea | ASIAN BOSS" on youtube. The doctor makes the comment at about 8:01 .

I haven’t heard of this “re-activation” before. Has anyone?
Also, the doctor mentions masks are effective.

I have and, at the moment and to the best of my understanding, there is a strong suspicion that it is only due to unreliable tests

But the absence/presence of similar cases in other countries using different tests (europe or US) should help validate/unvalidate this hypothesis.


Ah, I see. I assumed that all tests were very reliable. Thanks.