Conozca aspectos claves en la obtención del Plasma Rico en Plaquetas
Poner fin a las desigualdades es poner fin al sida y a las pandemias
DETALLES DEL ADJUNTO Miguel_German_Rueda_Biotest_1


Original article published in: medrxiv.org

Link: https://www.medrxiv.org/content/10.1101/2021.11.19.21266552v1

Co authors: Diego A. Álvarez-Díaz, Ana Luisa Muñoz, Pilar Tavera-Rodríguez, María T. Herrera-Sepúlveda, Hector Alejandro Ruiz-Moreno, Katherine Laiton-Donato, Carlos Franco-Muñoz, Dioselina Pelaez-Carvajal, Diego Cuellar, Alejandra M. Muñoz-Ramirez, Marisol Galindo, Edgar J. Arias-Ramirez, Marcela Mercado-Reyes

doi: https://doi.org/10.1101/2021.11.19.21266552

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Background Global 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.

Objectives To evaluate the sensitivity of the Mu variant (B.1.621) to neutralizing antibodies induced by the BNT162b2 vaccine.

Study design Three 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

Results The 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.

Conclusions This 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.


  • Mu and Gamma variants represented 49% and 25% of cases in Colombia by August 2021.
  • Increased proportion of SARS-COV-2 cases were mostly associated with Mu variant, despite being detected simultaneously with the VOC Gamma
  • The Mu variant remarkably escapes from neutralizing antibodies elicited by the BNT162b2-vaccine
  • Laboratory studies of neutralizing antibodies are useful to determine the efficacy of SARS-CoV-2 vaccines against VOC and VOI.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This work was funded by the Instituto Nacional de Salud project code CEMIN-04-2021 and Sistema General de Regalias (SGR) project code BPIN 2020000100151.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.


The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study protocol was approved by the Ethics Committee of the Colombian National Health Institute, (CEMIN)-04-2021, carried out in accordance with the Declaration of Helsinki. All subjects enrolled in this research responded voluntarily to an informed consent formulary.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.


I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).


I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.


Paper in collection COVID-19 SARS-CoV-2 preprints from medRxiv and bioRxiv


The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license.

Dra. Ana Luisa Muñoz – Directora Laboratorio de Investigación Hemolife.

Dr. Miguel Germán Rueda – CEO Hemolife

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