Reference:
Public Health England. (2021). SARS-CoV-2 variants of concern and variants under investigation in England: Technical briefing 17 (25 June 2021). Retrieved from https://www.gov.uk/phe
Summary:
The Technical Briefing 17 from Public Health England, dated 25 June 2021, reports on the surveillance of SARS-CoV-2 variants in England. As of that date, there are four variants of concern (VOC) and nine variants under investigation (VUI). Notably, the Delta variant (B.1.617.2) dominated, accounting for approximately 95% of sequenced cases. The document discusses operational issues affecting sequencing data and highlights the Lambda variant (C.37) as a significant new variant. Preliminary findings indicate a concerning trend in lower PCR cycle threshold values for Delta cases compared to Alpha cases, suggesting higher viral loads. The report also covers vaccine effectiveness against these variants and details secondary attack rates, indicating that Delta variant cases had higher transmission rates among close contacts. The technical briefing emphasises the importance of ongoing surveillance and research to monitor these variants’ behaviour, particularly concerning their transmissibility and vaccine resistance.