Pfizer and Astra Zenaca antibodies begin fading significantly beteen 21 and 41 days after fully dosed.
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01642-1/fulltext
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A significant trend of declining S-antibody levels was seen with time for both ChAdOx1 (p<0·001) and BNT162b2 (p<0·001; figure; appendix), with levels reducing by about five-fold for ChAdOx1, and by about two-fold for BNT162b2, between 21–41 days and 70 days or more after the second dose. This trend remained consistent when results were stratified by sex, age, and clinical vulnerability (appendix). For BNT162b2, S-antibody levels reduced from a median of 7506 U/mL (IQR 4925–11 950) at 21–41 days, to 3320 U/mL (1566–4433) at 70 or more days. For ChAdOx1, S-antibody levels reduced from a median of 1201 U/mL (IQR 609–1865) at 0–20 days to 190 U/mL (67–644) at 70 or more days.
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https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01642-1/fulltext
...
A significant trend of declining S-antibody levels was seen with time for both ChAdOx1 (p<0·001) and BNT162b2 (p<0·001; figure; appendix), with levels reducing by about five-fold for ChAdOx1, and by about two-fold for BNT162b2, between 21–41 days and 70 days or more after the second dose. This trend remained consistent when results were stratified by sex, age, and clinical vulnerability (appendix). For BNT162b2, S-antibody levels reduced from a median of 7506 U/mL (IQR 4925–11 950) at 21–41 days, to 3320 U/mL (1566–4433) at 70 or more days. For ChAdOx1, S-antibody levels reduced from a median of 1201 U/mL (IQR 609–1865) at 0–20 days to 190 U/mL (67–644) at 70 or more days.
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