SARS-COV-2 VARIANT SURVEILLANCE DURING THE SECOND WAVE IN ARGENTINA REFLECTS THE SOUTH AMERICA SCENARIO: HIGH PREVALENCE OF GAMMA AND LAMBDA

TORRES C (AUTORA PARA CORRESPONDENCIA); MOJSIEJCZUK L; ACUÑA D; ALEXAY S; AMADIO A; AULICINO P; DEBAT H; DUS SANTOS MJ; FAY F; FERNÁNDEZ F; GIRI A; GISMONDI MI; GOYA S; KÖNIG G; LUCERO H; NABAES JODAR M; PIANCIOLA L; SUÁREZ A; TITTARELLI E; ZUNINO S; PROYECTO PAIS; MISTCHENKO A; VALINOTTO L; VIEGAS M

Conferencia; ISIRV-WHO Virtual Conference, COVID-19, Influenza and RSV: Surveillance-Informed Prevention and Treatment; 2021

BackgroundThe emergence of SARS-CoV-2 variants with concerning characteristics to public health has attracted the attention of the scientific community and governments both regionally and globally since the end of 2020. MethodsMolecular surveillance of SARS-CoV-2 variants in Argentina was performed on a total of 4368 samples from the capital city and nine provinces, during 47 epidemiological weeks (EW) that covered the end of the first wave and the complete second wave of the COVID-19 pandemic in the country (EW 44/2020 to EW 37/2021). The surveillance strategy was mainly based on Sanger sequencing of a Spike coding region that allows the simultaneous identification of signature mutations associated with worldwide circulating variants. In addition, whole SARS-CoV-2 genome sequences were obtained from 542 samples. Results The main variants found were Gamma and Lambda and to a lesser extent, Alpha, Zeta, Epsilon, and more recently, Delta and Mu. Whereas Gamma dominated in different regions of the country, both Gamma and Lambda prevailed in the most populated area, the metropolitan region of Buenos Aires (MABA), although showing a heterogeneous distribution along this region. The major lineages that circulated on the first wave at the beginning of the studied period were almost completely replaced by worldwide and regional emergent variants in a term of few weeks. Al the end of the second wave, Delta and Mu started to be detected in local transmission cases. ConclusionsAt the international level, the current situation of variants reflects the sustained advance of the Delta, driving new waves in much of the globe. On the other hand, South America, which exhibits an exceptional landscape of variants dominated by the regionally emerged Gamma and Lambda begins to face Delta´s entry into a dynamic equilibrium of tension between viral evolution, immunity of the population associated with the second wave, and the asymmetry of vaccination campaigns and regional health policies. This cost-effective surveillance protocol allowed for a rapid response in a resource-limited access scenario, added information on the expansion of the Lambda variant in South America and contributed to the implementation of public health measures to control the disease spread in Argentina.