Waning of IgG, total and neutralizing antibodies 6 months post-vaccination with BNT162b2 in healthcare workers

Abstract

Data about the duration of humoral response following COVID-19 vaccines are mandatory to establish appropriate population vaccination strategy. This study reports on the antibody decline observed in a population of COVID-19 naïve and COVID-19 positive individuals having received the two dose regimen of the BNT162b2 vaccine. Six months after vaccination, a significant antibody decline was observed in both COVID-19 naïve and positive individuals. The estimated half-life of total and IgG antibodies differs and ranges from several months for total antibodies to only several weeks for IgG antibodies, explaining the significant proportions of participants with non-detectable levels of neutralizing antibodies at 6 months. Whether this decrease correlates with an equivalent drop in the clinical effectiveness against the virus will require appropriate clinical studies. Nevertheless, these data are already important to support the decision-making on the potential use of a booster dose.

Total anti-SARS-CoV-2 antibodies measured 6 months after Pfizer-BioNTech COVID-19 vaccination in healthcare workers

“…The preliminary results of this ad-interim analysis of anti-SARS-CoV-2 humoral immunity in healthcare workers who received a complete (2-dose) cycle of Pfizer-BioNTech COVID-19 vaccination reveal that a gradual decline of total anti-SARS-CoV-2 antibodies (and hence of neutralizing potential) has occ urred 6 months after vaccination, though the antibodies values have remained still considerably higher than the method-dependent cut-off and no seronegativization seems to have occurred in either baseline seronegative or seropositive subjects. These results compared rather well with other preliminary data made available by Bayart and colleagues [6] , who also showed that the decay of anti-SARS-CoV-2 RBD total antibodies after 6 months from Pfizer-BioNTech COVID-19 vaccine administration was around 55% in seronegative healthcare workers, thus nearly identical to the 57% decrease that we found in our cohort over an identical period of monitoring. Although better medium-term response would have been theoretically expected in subjects with double immunization (i.e., SARS-CoV-2 infection followed by full vaccination), we instead found that total anti-SARS-CoV-2 antibodies reduction appeared larger in baseline seropositive than seronegative recipients (i.e., 74% vs. 52%) ( Figure 2 ).…”

Waning immune responses against SARS-CoV-2 variants of concern among vaccinees in Hong Kong

“…Moreover, our findings on waning NAb responses to wildtype virus among BNT162b2-vaccinees are consistent to several studies published recently. 19,27,31,32 Importantly, against the global panel of VOCs, NAb response rates and titers among Corona-Vac-vaccinees were not only significantly lower but also disappeared more dramatically just three months after the vaccinations as compared with BNT162b2-vaccinees. CoronaVac-vaccinees also exhibited lower neutralization potency index and waning spike-specific IFN- (i) and spike-specific IFN-g + CD4 + (j) or CD8 + T cells (k) to IC 50 against wild type (WT) as well as spike-specific IFN-g + CD4 + and CD8 + T cells (l) .…”

Past COVID-19 and immunosuppressive regimens affect the long-term response to anti-SARS-CoV-2 vaccination in liver transplant recipients

“…Our findings could be considered unexpected, since the effect of immunosuppressive therapies could reduce antibody response duration over time more rapidly compared to immunocompetent patients. In a recent report conducted in healthcare professionals, six months after a full course of BNT162b2 vaccine, antibody titer decline was observed in approximately 89.6% of cases, and approximately 45% of them became seronegative 23 . However, the peak response in these patients was reached 1 month after the second vaccine dose, which was earlier than what we observed in our series.…”