RESUMEN
Studies about the evolution of SARS-CoV-2 lineages in different backgrounds such as naive populations, are still scarce, especially from South America. The aim of this work was to study the introduction and diversification pattern of SARS-CoV-2 during the first year of the COVID-19 pandemic in the Northwestern Argentina (NWA) region and to analyze the evolutionary dynamics of the main lineages found. In this study, we analyzed a total of 260 SARS-CoV-2 whole-genome sequences from Argentina, belonging to the Provinces of Jujuy, Salta and Tucuman, from March 31st, 2020, to May 22nd, 2021, which covered the full first wave and the early second wave of the COVID-19 pandemic in Argentina. In the first wave, eight lineages were identified: B.1.499 (76.9%), followed by N.5 (10.2%), B.1.1.274 (3.7%), B.1.1.348 (3.7%), B.1 (2.8%), B.1.600 (0.9%), B.1.1.33 (0.9%) and N.3 (0.9%). During the early second wave, the first-wave lineages were displaced by the introduction of variants of concern (VOC) (Alpha, Gamma), or variants of interest (VOI) (Lambda, Zeta, Epsilon) and other lineages with more limited distribution. Phylodynamic analyses of the B.1.499 and N.5, the two most prevalent lineages in NWA, revealed that the substitution rate of lineage N.5 (7.9 x 10-4 substitutions per site per year, s/s/y) was a [~]40% faster than that of lineage B.1.499 (5.9 x 10-4 s/s/y), although both are in the same order of magnitude than other non-VOC lineages. No mutations associated with a biological characteristic of importance were observed as signatures markers of the phylogenetic groups established in Northwestern Argentina, however, single sequences in non-VOC lineages did present mutations of biological importance or associated with VOCs as sporadic events, showing that many of these mutations could emerge from circulation in the general population. This study contributed to the knowledge about the evolution of SARS-CoV-2 in a pre-vaccination and without post-exposure immunization period.
RESUMEN
We hypothesized that in individuals with previous SARS-CoV-2 infection, the first vaccine dose would work as a booster, eliciting a faster and more intense immune response. We herein describe antibody responses to the first and second doses of Gam-COVID-Vac (SPUTNIK V) vaccine in health personnel of Tucuman, Argentina, with previous COVID-19 and compared it with uninfected personnel. Individuals with anti-SARS-CoV-2 titers at baseline showed significantly higher responses to the first dose than people with no prior history of disease (p <0.0001), with titers higher to those registered after the second dose in the control group, representing a clear secondary antibody response. This suggests that a single dose of SPUTNIK V for people with previous SARS-CoV-2 infection could contribute to a better use of available doses. One-Sentence SummaryFirst vaccine dose in subjects with prior COVID19 elicits a higher antibody response than two doses in uninfected individuals
RESUMEN
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) first reported in Wuhan has caused a global pandemic with dramatic health and socioeconomic consequences. The Coronavirus Disease 2019 (COVID-19) associated represents a challenge for health systems that had to quickly respond developing new diagnostic and therapeutic strategies. In the present work, we developed an "In House" ELISA with high sensitivity (92.2 %), specificity (100%) and precision (93.9%), with an area under the ROC curve (AUC) of 0.991, rendering the assay as an excellent serological test to correctly discriminate between SARS-COv-2 infected and non-infected individuals and study population seroprevalence. Among 758 patients evaluated for SARS-CoV-2 diagnosis in the province of Tucuman, Argentina, we found a Pearson correlation coefficient of 0.5048 between antibodies elicited against the RBD and the nucleocapsid (N) antigen. Additionally, 33.6% of individuals diagnosed with COVID-19 displayed mild levels of RBD-IgG antibodies, while 19% of the patients showed high antibody titers. Interestingly, patients with SARS-COV-2 infection over 60 years old elicited significantly higher levels of IgG antibodies against RBD compared to younger ones, while no difference was found between women and men. Surprisingly, individuals from a high altitude village displayed statistically significant higher and longer lasting anti-RBD antibodies compared to those from a city at a lower altitude, suggesting that a hypobaric hypoxia-adapted mechanism may act as a protective factor for COVID-19. To our knowledge, this is the first report correlating altitude with increased humoral immune response against SARS-Cov-2 infection.