Surveillance of seasonal respiratory viruses among Chilean patients during the COVID-19 pandemic

The StudySARS-CoV-2 has generated over 122 million cases worldwide. Non-pharmaceuticals interventions such as confinements and lockdowns started in Chile on March 18th 2020. In Europe, confinements and lockdowns have been accompanied by a decrease in the circulation of other respiratory viruses such as Influenza A virus(IAV), Influenza B virus(IBV) or respiratory syncytial virus(RSV) (1). Although changes in circulation patterns of respiratory viruses have been reported, limited information regarding the southern hemisphere is available where the SARS-CoV-2 pandemic merged with the winter season. We conducted viral surveillance of respiratory viruses and we evaluated their presence and establishing whether they were co-circulating with SARS-CoV-2.

Infectivity and immune escape of the new SARS-CoV-2 variant of interest Lambda

BackgroundThe newly described SARS-CoV-2 lineage C.37 was recently classified as a variant of interest by the WHO (Lambda variant) based on its high circulation rates in South American countries and the presence of critical mutations in the spike protein. The impact of such mutations in infectivity and immune escape from neutralizing antibodies are entirely unknown. MethodsWe performed a pseudotyped virus neutralization assay and determined the impact of the Lambda variant on infectivity and immune escape using plasma samples from healthcare workers (HCW) from two centers in Santiago, Chile who received the two-doses scheme of the inactivated virus vaccine CoronaVac. ResultsWe observed an increased infectivity mediated by the Lambda spike protein that was even higher than that of the D614G (lineage B) or the Alpha and Gamma variants. Compared to the Wild type (lineage A), neutralization was decreased by 3.05-fold for the Lambda variant while it was 2.33-fold for the Gamma variant and 2.03-fold for the Alpha variant. ConclusionsOur results indicate that mutations present in the spike protein of the Lambda variant of interest confer increased infectivity and immune escape from neutralizing antibodies elicited by CoronaVac. These data reinforce the idea that massive vaccination campaigns in countries with high SARS-CoV-2 circulation must be accompanied by strict genomic surveillance allowing the identification of new isolates carrying spike mutations and immunology studies aimed to determine the impact of these mutations in immune escape and vaccines breakthrough.

SARS-CoV-2 Detection in Sewage in Santiago, Chile - Preliminary results.

The detection of viruses in sewage is a method of environmental surveillance, which allows evaluating the circulation of different viruses in a community. This study presents the first results of sewage surveillance to detect the circulation of SARS-CoV-2 virus in Santiago, Chile. Using ultracentrifugation associated with RT-qPCR, we detected SARS-CoV-2 in untreated and treated wastewater samples obtained two treatment plants, which together process around 85% of the wastewater from the city. This is the first report of detection of SARS-CoV-2 in sewage in Chile and indicates that wastewater surveillance could be a sensitive tool useful as a predictive marker of the circulation of the virus in a population and therefore, be used as an early warning tool.

SARS-CoV-2 detection from nasopharyngeal swab samples without RNA extraction

The ongoing COVID-19 pandemic has reached more than 200 countries and territories worldwide. Given the large requirement of SARS-CoV-2 diagnosis and considering that RNA extraction kits are in short supply, we investigated whether two commercial RT-qPCR kits were compatible with direct SARS-CoV-2 detection from nasopharyngeal swab samples. We show that one of the tested kits is fully compatible with direct SARS-CoV-2 detection suggesting that omission of an RNA extraction step should be considered in SARS-CoV-2 diagnosis.