RESUMEN
Emerging SARS-CoV-2 strains continue to generate difficulties for authorities and health care professionals worldwide due to enhanced transmissibility and/or immune response evasion. The appearance of the Alpha and Delta strains has been associated with substantial increases in the number of COVID-19 cases and associated deaths. Whole Genome Sequencing (WGS) continues to be the gold standard for molecular surveillance of the pandemics but other assays such as mutation genotyping can be used to reduce costs and allocated time. This study investigates the efficiency of mutation screening tests compared to WGS and their predictive value to anticipate future waves. A very high degree of fidelity for this type of assay was found, regardless of the method used. The positive predictive value (PPV) of 4/5 markers was over 95% for the detection of Alpha and Delta variants. By estimating the prevalence of the Alpha and Delta strains using genotyping assays and fitting the data to a mathematical model, a five week period between the point of exponential growth of variant prevalence and a drastic increase in case numbers was found. For that reason, raising awareness about the efficacy of mutation screening could help authorities adopt better measures in the future.
RESUMEN
New SARS-CoV-2 variants are constantly emerging and putting a strain on public health systems by spreading faster and potentially evading immune protection through vaccination. One of these strains is the B.1.1.7 variant that has initially been described in the United Kingdom and has subsequently spread to several countries. Monitoring the amplification of the S gene-a major hotspot for molecular evolution-by reverse transcription polymerase chain reaction (RT-PCR) allows rapidly screening for such variants. This report describes the detection of sequence variants in Romania by using this strategy followed by next-generation sequencing of the entire genome for confirmation and further characterization. One B.1.1.7 and three B.1.258 sequences were confirmed. Each of these strains presented additional mutations with possible impact on the replicative capacity. Public health strategies should be devised to ensure molecular monitoring of SARS-CoV-2 evolution during the pandemic and allow adequate and rapid reaction.
