Velandy Manohar, MD.,
Distinguished Life Fellow, Am. Psychiatric Association
Med. Dir. CT Aware Recovery Care.
The decline of anti-RBD antibodies three months after the second dose of BNT162b2 is of concern because it raises the possibility of a short-lived humoral immunity after vaccination. Booster doses of BNT162b2 might be required to maintain high titers of anti-RBD antibodies over time.
Conclusion: Our data showed differences between the antibody responses raised after the first and second BNT162b2 vaccination, in particular lower frequencies of neutralizing antibodies in the elderly group. This suggests that this population needs to be closely monitored and may require earlier revaccination or/and an increased vaccine dose to ensure stronger long lasting immunity and protection against infection.
The durability of circulating neutralizing antibody (nAb) responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and their boosting by vaccination remains to be defined. We show that outpatient and hospitalized SARS-CoV-2 seropositive individuals mount a robust neutralizing antibody (nAb) response that peaks at days 23 and 27 post-symptom onset, respectively. Although nAb titers remained higher in hospitalized patients, both study groups showed long-lasting nAb responses that can persist for up to 12 months after natural infection. These nAb responses in previously seropositive individuals can be significantly boosted through immunization with two doses of the CoronaVac (Sinovac) or one dose of the BNT162b2 (BioNTech/Pfizer) vaccines, suggesting a substantial induction of B cell memory responses. Noteworthy, three obese previously seropositive individuals failed to mount a booster response upon vaccination, warranting further studies in this population. Immunization of naïve individuals with two doses of the CoronaVac vaccine or one dose of the BNT162b2 vaccine elicited similar levels of nAbs compared to seropositive individuals 4.2 to 13.3 months post-infection with SARS-CoV-2. Thus, this preliminary evidence suggests that both, seropositive and naïve individuals, require two doses of CoronaVac to ensure the induction of robust nAb titers
Nov 20 2021 [ Booster have a key role in augmenting and sustaining immune response to SARS CoV-2}
Two-dose messenger RNA vaccines (BNT162b2/Pfizer and mRNA-1273/Moderna) against SARS-CoV-2 were rolled out in the US in December 2020, and provide protection against hospitalization and death from COVID-19 for at least six months. Breakthrough infections have increased with waning immunity and the spread of the B.1.617.2 (Delta) variant in summer 2021, prompting approval of boosters for all adults over 18.
We measured anti-receptor binding domain (RBD) IgG and surrogate virus neutralization of the interaction between SARS-CoV-2 spike protein and the human angiotensin-converting enzyme (ACE2) receptor, before and after boosters in N=33 healthy adults. We document large antibody responses 6-10 days after booster, with antibody levels that exceed levels documented after natural infection with COVID-19, after two doses of vaccine, or after both natural infection and vaccination.
Surrogate neutralization of B.1.617.2 is high but reduced in comparison with wild-type SARS-CoV-2. These data support the use of boosters to prevent breakthrough infections and suggest that antibody-mediated immunity may last longer than after the second vaccine dose.