So what is rebound C19 and how often does it happen?
Definition: The recurrence of C19 symptoms (or a new positive test) 2 to 8 days after testing negative from the first round of C19 infection.
How often does it happen? Well the answer is not as clear as we’d like for right now! After looking through the literature that has measured and quantified rebound, these are my general takeaways.
1. Not all rebound cases are symptomatic (you can have a new positive test but not show symptoms).
2. Rebound occurs not only in those who take Paxlovid, but also in those who do not.
3. The likelihood of rebound appears to be slightly higher after taking Paxlovid. How much higher? Too much ambiguity in the data to say right now.
4. The immune response in patients who took Paxlovid and rebounded appears to be just as good if not better than those who didn’t rebound, suggesting that the rebound isn’t happening because the course of treatment is too short.
I wish there was a clearer answer around the mechanism of action and rates of rebound but for now we will have to wait for more data!
Importantly, if you become symptomatic a few days after getting over a C19 infection, take a test to check for rebound. If you are going to be around really vulnerable individuals, consider taking a test before seeing them even if you are asymptomatic and just got over your initial infection.