RESUMEN
Background: We tested the antibody response to SARS-CoV-2 vaccination in individuals with and without previous infection that received different vaccination strategies. Methods: We recruited 203 volunteers. Individuals who have had SARS-CoV-2 infection during the six months preceding vaccination received one dose (group 1), the others received two (group 2). After 3 months, 98 subjects received a booster dose. Anti-SARS-CoV-2 Spike RBD IgG were tested in all subjects before vaccination (T0), and at 15 (T15), 90 (T90), 180 (T180) and 360 (T360) days after second or single dose; additionally, in group 2, IgG were tested 10 days after the vaccination (T10). Results: The difference of IgG concentration between the groups was statistically significant (p<0.05) at T0, T15 and T90, but not at T180 (p=0.713) and T360 (p=0.069). At T0 and T90 the antibody titre was higher in group 1, but it dropped in all volunteers 90 days after vaccination. Most of infections after vaccination occurred between T90 and T180. Conclusions: Antibody titre is significantly associated with a previous SARS-CoV-2 infection. Probability of contracting the infection increases after three months from primary vaccination, even among who had a previous infection, confirming the efficacy of vaccination as a preventive measure against SARS-CoV-2 infections and the need of booster administrations.
RESUMEN
BACKGROUND: Although more than a year has passed since the start of the pandemic, SARS-CoV-2 infection still represents a major challenge for public health all over the world due to viral genome capability of gaining rapid mutations. Whole-genome sequencing (WGS) is the gold standard for variant identification, but it is time consuming and relatively expensive. For this reason, assays targeting multiple regions of the SARS-CoV-2 genome may be useful for a rapid traceability of either known or new variants, anyway, not all the manufacturers are able to sustain the rapid development of variants. OBJECTIVE: We tested forty nasopharyngeal swabs, resulted positive for the presence of SARS-CoV-2 RNA at low cycle threshold (CT < 25), with SARS-CoV-2 Variants ELITe MGB® Kit, which was designed to identify Nigerian variant, possible UK variant and South African or Brazilian variant. RESULTS: During the analysis, we noted an atypical melting curve, different from the other variants recognizable by the kit. The subsequent WGS reported this variant as Kappa, so we assess the possibility of "suspecting" the presence of a Kappa variant using SARS-CoV-2 Variants ELITe MGB® Kit. CONCLUSIONS: Rapid variant screening followed by WGS offers the opportunity to study mutation dynamics and quickly identify possible variants of interest (VOI) and/or variants of concern (VOC), which is crucial in virus spreading control. Furthermore, an accurate analysis of the melting peak could be useful to suspect the presence of new variants.
