Severity, Pathogenicity and Transmissibility of Delta and Lambda Variants of SARS-CoV-2, Toxicity of Spike Protein and Possibilities for Future Prevention of COVID-19.

The World Health Organization reports that SARS-CoV-2 has infected over 220 million people and claimed over 4.7 million lives globally. While there are new effective vaccines, the differences in behavior of variants are causing challenges in vaccine development or treatment.