Project description:BackgroundThe emergence of the new SARS-CoV-2 Omicron variant, which is known to have a large number of mutations when compared to other variants, brought to light the concern about vaccine escape, especially from the neutralization by antibodies induced by vaccination.MethodsBased on viral microneutralization assays, we evaluated in 90 individuals the impact on antibody neutralization induction, against Omicron variant, by a booster dose of BNT162b2 mRNA vaccine after the CoronaVac primary vaccination scheme.ResultsHere we show that the percentage of seroconverted individuals 30 and 60 days after CoronaVac scheme was 16.6% and 10%, respectively. After booster dose administration, the seroconvertion rate increased to 76.6%. The neutralization mean titer against Omicron in the CoronaVac protocol decreased over time, but after the booster dose, the mean titer increased 43.1 times.ConclusionsThese results indicate a positive impact of this vaccine combination in the serological immune response against SARS-CoV-2 Omicron variant.
Project description:To raise awareness about preventive measures in COVID-19 pandemic, even though fully vaccinated. Although recent trials showed high efficacy of vaccines in preventing symptomatic infections, there are some individuals experiencing symptomatic SARS-CoV-2 infection. In this case report, a fully vaccinated young dental practitioner experienced symptomatic SARS-CoV-2 infection 55 days postvaccination with BNT162b2 Pfizer vaccine with evident ageusia. Diagnostic swabs were performed and used for viral genome sequencing. The patient fully recovered 15 days after diagnosis. Loss of smell and taste, together with nasal congestion were the main reported symptoms. The use of personal protective equipment prevented spread of infection in patients and co-workers. With the increase of people being fully vaccinated, it is still necessary to follow infection preventive protocols by correctly applying personal protective equipment. Although high efficacy has been proved, some individuals may still be vulnerable to symptomatic infection and new guidelines and markers should be adopted and investigated to find out patients for whom vaccination may not determine full immunization.
Project description:The response of the adaptive immune system is augmented by multimeric presentation of a specific antigen, resembling viral particles. Several vaccines have been designed based on natural or designed protein scaffolds, which exhibited a potent adaptive immune response to antigens; however, antibodies are also generated against the scaffold, which may impair subsequent vaccination. In order to compare polypeptide scaffolds of different size and oligomerization state with respect to their efficiency, including anti-scaffold immunity, we compared several strategies of presentation of the RBD domain of the SARS-CoV-2 spike protein, an antigen aiming to generate neutralizing antibodies. A comparison of several genetic fusions of RBD to different nanoscaffolding domains (foldon, ferritin, lumazine synthase, and β-annulus peptide) delivered as DNA plasmids demonstrated a strongly augmented immune response, with high titers of neutralizing antibodies and a robust T-cell response in mice. Antibody titers and virus neutralization were most potently enhanced by fusion to the small β-annulus peptide scaffold, which itself triggered a minimal response in contrast to larger scaffolds. The β-annulus fused RBD protein increased residence in lymph nodes and triggered the most potent viral neutralization in immunization by a recombinant protein. Results of the study support the use of a nanoscaffolding platform using the β-annulus peptide for vaccine design.
Project description:A low anti-spike antibody response of 28.6% was observed 28 days after BNT162b2 vaccine second dose among 133 solid organ transplant-recipients without previous COVID-19. No serious adverse events were recorded. Four severe COVID-19 cases were reported between or after the two doses. Our data suggests to change the vaccine strategy.
Project description:BackgroundCoronavirus disease 2019 (COVID-19) is associated with increased morbidity and mortality in older adults. Although the advent of the first vaccines has significantly reduced these rates, data on older adults in clinical trials are scarce.ObjectivesWe quantified and compared the humoral response in individuals with vs. without pre-existing seropositivity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in a cohort of 69 patients living in a nursing home and who had received the recommended two doses of the Comirnaty (Pfizer-BioNTech®) vaccine.ResultsAll 69 patients (100%) tested positive for antibodies against SARS-CoV-2 at 2 months post-vaccination. Residents with a pre-vaccination infection had significantly higher titers of anti-spike 1 IgG than those with no prior infection (median [interquartile range]: 55,726 [14463-78852] vs. 1314 [272-1249] arbitrary units, respectively; p < 0.001). The same result was observed for neutralizing antibodies titers (704 [320-1280] vs. 47 [20-40] respectively; p < 0.001). Between the pre-vaccination and post-vaccination periods, for IgG and neutralizing antibodies, we observed a 49 and 8-fold increase respectively. In comparison to the wild-type Receptor Binding Domain (RBD), the binding capacity of these vaccine sera was significantly decreased on the B.1.351 and P.1 variants RBD but not decreased with respect to the B.1.1.7 RBD. Although all nursing home residents developed a humoral response following Comirnaty vaccine, its intensity appeared to depend on the pre-vaccination serological status.ConclusionOur results raise the question of how many doses of vaccine should be administered in older and how long the protection will be effective.