Once researchers understand how the immune response induced by a vaccine correlates to vaccine efficacy against the new variants, it will be easier to accurately determine the efficacy from neutralisation assays alone. It is also possible to analyse how vaccines perform against the new variants by determining the efficacy of the vaccine in a specific group of those who have become infected with one of the SARS-CoV-2 new variants in the context of the clinical trials. ![]() 18-20 For further information on how the immune response induced by vaccines is evaluated, please click here. T cells work to activate different parts of the immune system or directly kill invading substances such as viruses and bacteria, and have been shown to play a key role in the immune response to SARS-CoV-2. The in vitro studies only probe the capacity of antibodies to neutralise variants in the laboratory, and not the wider effects of other components of the immune response such as T-cell activation. 9-13Įxample of an assay to determine the ability of previously developed neutralising antibodies against the original virus to neutralise a SARS-CoV-2 variant. Consequently, these mutations can affect SARS-CoV-2 in an advantageous or disadvantageous way. ![]() The spike protein is also a part of the structure of the virus where neutralising antibodies bind to block the SARS-CoV-2 infection. 8 The mutations in these variants lead to small changes in the structure of the spike protein, which is the protein used by the virus to enter human cells. There are also early data to suggest that the UK variant is associated with a higher mortality risk than the wild-type SARS-CoV-2. The UK (B.1.1.7), South African (B.1.351) and Brazilian (P.1) variants have mutations which are thought to make them more transmissible. 7Ĭurrently, there are three variants of concern, which are named based on the country where they were first identified. However, this variant was declared extinct just a few months later and is no longer in circulation. For instance, in June 2020, a concerning SARS-CoV-2 variant thought to present a decreased sensitivity to the immune response was detected in mink in the Netherlands and Denmark. 6 Variants can also become extinct due to natural selection. ![]() The mutation likely increased the affinity of the virus to bind to the human receptor ACE2, resulting in higher infectivity and transmission rates. The SARS-CoV-2 variant containing the D614G mutation quickly spread around the world.įor example, the variant containing the D614G mutation has become the wild-type (predominant) form of SARS-CoV-2 worldwide since mid-2020.
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