RESUMO
The healthcare workers are considered as a high-risk group for infection with SARS-CoV-2, so they were included in the first stage of the National Plan for Vaccination against COVID-19 in Colombia. An ongoing prospective cohort study to evaluate immune response to vaccination included 490 workers from health institutions in Bogota, Colombia, vaccinated between March and June 2021 with BNT162b2 (Pfizer-BioNtech). Multiple samples were collected during a follow-up period of 6 months after immunization. We report cases of asymptomatic and symptomatic SARS-CoV-2 infections detected in this cohort. For each participant demographic data, vaccination dates, results for SARS-CoV-2 RT-PCR, and detection of antibody (IgG) tests during the follow-up period were collected. SARS-CoV-2 infection was detected in 38 (7.7 %) volunteers. Of these, 81.6% had a positive RT-PCR for SARS-CoV-2, and 18.4% were confirmed by detection of IgG anti-SARS-CoV-2 nucleoprotein; 76.3% of infections occurred after 7 days of second dose. A total of 57.9% of the cases were asymptomatic. No hospitalizations or deaths were registered. When infection occurred, 81.6% of infected participants had presence of IgG anti-S antibodies. In 12 samples in which genomic characterization was achieved, 83.4% corresponded to the variant Mu, 8.3% Gamma, and 8.3% Delta. All findings agree with other reports in different studies that show the benefit of COVID-19 vaccines, protecting specially against severe disease but not against infection or re-infection.
RESUMO
BackgroundGlobal surveillance programs for the virus that causes COVID-19 are showing the emergence of variants with mutations in the Spike protein, including the Mu variant, recently declared a Variant of Interest (VOI) by the World Health Organization. Genomic and laboratory surveillance is important in these types of variants because they may be more infectious or less susceptible to antiviral treatments and vaccine-induced antibodies. ObjectivesTo evaluate the sensitivity of the Mu variant (B.1.621) to neutralizing antibodies induced by the BNT162b2 vaccine. Study designThree of the most predominant SARS-CoV-2 variants in Colombia during the epidemiological peaks of 2021 were isolated. Microneutralization assays were performed by incubating 120 TCDI50 of each SARS-CoV-2 isolate with five 2-fold serial dilutions of sera from 14 BNT162b2 vaccinated volunteers. The MN50 titer was calculated by the Reed-Muench formula ResultsThe three isolated variants were Mu, a Variant of Interest (VOI), Gamma, a variant of concern (VOC), and B.1.111 that lacks genetic markers associated with greater virulence. At the end of August, the Mu and Gamma variants were widely distributed in Colombia. Mu was predominant (49%), followed by Gamma (25%). In contrast, B.1.111 became almost undetectable. The evaluation of neutralizing antibodies suggests that patients vaccinated with BNT162-2 generate neutralizing antibody titers against the Mu variant at significantly lower concentrations relative to B.1.111 and Gamma. ConclusionsThis study shows the importance of continuing with surveillance programs of emerging variants as well as the need to evaluate the neutralizing antibody response induced by other vaccines circulating in the country against Mu and other variants with high epidemiological impact. HighlightsO_LIMu and Gamma variants represented 49% and 25% of cases in Colombia by August 2021. C_LIO_LIIncreased proportion of SARS-COV-2 cases were mostly associated with Mu variant, despite being detected simultaneously with the VOC Gamma C_LIO_LIThe Mu variant remarkably escapes from neutralizing antibodies elicited by the BNT162b2-vaccine C_LIO_LILaboratory studies of neutralizing antibodies are useful to determine the efficacy of SARS-CoV-2 vaccines against VOC and VOI. C_LI