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Reinfection, Reactivation, and Relapses — What we Know and Don’t Know About COVID Immunity
The World Health Organization has cautioned us that there’s “no evidence” of immunity after catching COVID, whilst scientists have found “good neutralizing antibodies” in the blood of survivors. Many people were alarmed by the report of sailors from an aircraft carrier apparently catching COVID-19 twice in quick succession. The fear is obvious. If nobody gets immunity then there can’t be a vaccine and we can never beat this thing.
So, let’s unpack this some and talk a bit about immunity, reinfection, and relapses.
How Do We Get Immunity?
Our bodies have two levels of immune system. The first level is the innate immune system. This identifies intruders and fights a holding action while the second level, the adaptive immune system, prepares its weapons.
In some cases the innate immune system may defeat a virus before the adaptive immune system really gets into gear. This can result in not developing immunity, and sometimes happens with colds. If you get a very mild cold, give it to a coworker, then get it back from them, likely your adaptive immune system never woke up.
When your adaptive immune system wakes up, cells called B lymphocytes start to experiment with antibodies…