Not only that, J&J is also doing a trial for 2nd shot, as well as some places such as UK ended up doing Pfizer/Moderna with one shot only with delayed 2nd shot

Not only that, J&J is also doing a trial for 2nd shot, as well as some places such as UK ended up doing Pfizer/Moderna with one shot only with delayed 2nd shot (3-4 months later). So we'll see how that works out, there may be the possibility of getting a 2nd shot of J&J later down the line to increase your immunity. I believe Pfizer has even started doing 3rd shot boosters for very early phase 1-2 people from last year.