"Extremely rare" among those with suppressed immune system ONLY, not for rest of the world. You are out of that count and for you, 3 months test is final and conclusive
Extremely rare....In the sense is that possible???
Normally within 4 to 6 weeks, antibodies are formed, however for a test to said to be conclusive, 3 months time is enough where almost everyone with normal immune system, develops detectable amount of antibodies. Those with suppressed immune system due to meds, (chemotherapy for instance), this period is 6 months. 10 months time is extremely rare and not heard of