ABSTRACT
A comprehensive SARS-CoV-2 genomic surveillance programme that integrates logistics, laboratory work, bioinformatics, analytics, and timely reporting was deployed through a public-private partnership in the city of Bengaluru, Karnataka in India. As a result, 12461 samples have been sequenced and reported to the Karnataka State public health officials as time-sensitive, decision support during the last one year and uploaded in global public databases in a timely manner. This programme has developed an analytics platform for studying SARS-CoV-2 sequences and their epidemiological context. Continuous sequencing effort enabled timely detection of emergence of Omicron variant in India and the subsequent spread of the same and its sub-lineages with more logistic growth (BA.10, BA.12 and BA.5) in Bengaluru. Our data also helped to provide timely information on variants to determine which of the Variants of Concern tracked globally, were observed in Bengaluru, ensuring targeted efforts and reducing unwarranted fear. This effort highlights the importance of, and the urgent need to, increase genomic surveillance to support the states with limited sequencing and bioinformatics capacity. We describe the development and deployment of this end-to-end solution for genomic surveillance of SARS-CoV-2 in the city of Bengaluru.
ABSTRACT
Purpose: Compared to nasopharyngeal/oropharyngeal swabs, non-invasive saliva samples have enormous potential for scalability and routine population screening of SARS-CoV-2. In this study, we are investigating the efficacy of saliva samples relative to nasopharyngeal/oropharyngeal swabs for use as a direct source for the RT-PCR based SARS-CoV-2 detection. Methods: Paired nasopharyngeal/oropharyngeal swabs and saliva samples were collected from suspected positive SARS-CoV-2 patients and tested using RT-PCR. Generalised linear models were used to investigate factors that explain result agreement. Further, we used simulations to evaluate the effectiveness of saliva-based screening in restricting the spread of infection in a large campus such as an educational institution. Results: We observed 75.4% overall result agreement. Prospective positive samples stored for three or more days showed a drastic reduction in the probability of result agreement. We observed 83% result agreement and 74.5% test sensitivity in samples processed and tested within two days of collection. Our simulations suggest that a test with 75% sensitivity, but high daily capacity can be very effective in limiting the size of infection clusters in a workspace. Guided by these results, we successfully implemented a saliva-based screening in the Bangalore Life Sciences Cluster (BLiSC) campus. Conclusion: These results suggest that saliva may be a viable sample source for SARS-CoV-2 surveillance if samples are processed immediately. We strongly recommend the implementation of saliva-based screening strategies for large workplaces and in schools, as well as for population-level screening and routine surveillance as we learn to live with the SARS-CoV-2 virus.