RSV reemergence in Argentina since the SARS-CoV-2 pandemic.

INTRODUCTION: The community mitigation measures taken because of the COVID-19 pandemic had side effects on the circulation of the most frequent respiratory viruses during 2020. In the case of respiratory syncytial virus (RSV), an important paediatric pathogen, a decrease in the number of cases and delayed outbreaks was previously described. AIM AND METHODS: The genetic characteristics of the RSV circulating strains in paediatric patients in Buenos Aires, Argentina before and during the COVID-19 pandemic were studied. RSV (+) samples taken from hospitalised patients with respiratory tract infections (2018- 2021) were analysed through G gene sequencing and evolutionary analyses. RESULTS: No RSV hospitalised paediatric patients were registered in Buenos Aires during 2020; however, RSV reemerged in 2021 with a lower number of cases and a delayed outbreak, peaking in July-August. A total of 147 G gene sequences were analysed. RSV-B (N = 85) predominated during 2018 and 2021 whereas in 2019 RSV-A were more prevalent (N = 62). All RSV-A sequences were ON1-like strains, and all RSV-B were BA-like. Phylogenetic analyses showed that the same genetic lineages circulated before and after 2020, but RSVs from 2021 corresponded to new viral introductions rather than cryptic circulation of the previous genetic clusters in Buenos Aires during 2020. CONCLUSIONS: Following the reopening of borders, the reemergence of RSV in Argentina brought new viral introductions from other countries. Therefore, it is important to continue a deep global molecular surveillance to characterise RSV strains in post-pandemic circulation with an impact in future vaccine implementation.

Temporal Increase in Neutralization Potency of SARS-CoV-2 Antibodies and Reduced Viral Variant Escape after Sputnik V Vaccination

Recent studies have shown a temporal increase in the neutralizing antibody potency and breadth to SARS-CoV-2 variants in coronavirus disease 2019 (COVID-19) convalescent individuals. Here, we examined longitudinal antibody responses and viral neutralizing capacity to the B.1 lineage virus (Wuhan related), to variants of concern (VOCs: Alpha, Beta, Gamma, and Delta) and a local variant of interest (VOI: Lambda) in volunteers receiving the Sputnik V vaccine in Argentina. A collection of 472 serum samples obtained between January and September 2021 was used. The analysis indicates that while anti-spike IgG levels significantly wane over time, the neutralizing capacity to the first-wave linages of SARS-CoV-2 and VOC are maintained within four months of vaccination. In addition, an improved antibody cross-neutralizing ability to circulating variants of concern (Beta, Gamma and Delta) was observed over time of vaccination. The viral variants that displayed higher escape to neutralizing antibodies with respect to the original virus (Beta and Gamma variants) were the ones showing the largest increase in susceptibility to neutralization over time after vaccination. Our observations indicate that serum neutralizing antibodies are maintained for at least four month and show a reduction of VOC escape over time of vaccination.