Vaccines will generate what is called a “polyclonal antibody response”, which means that the vaccine generates antibodies to many components of the viral proteins which limit the impact of specific mutations. Depending on the vaccine, they can also generate T-cells, which may be very important to ensuring long term protection, preventing severe disease, and possibly containing variant spread.
In vitro laboratory testing showed that currently available RNA-based vaccines (Pfizer/BioNtech and Moderna) have retained efficacy against the Alpha (B.1.1.7) variant. In contrast, the in vitro testing has shown that the capacity of the antibodies generated by currently available vaccines to neutralize the Beta, Gamma, and Delta variants was decreased. However, the in vivo clinical studies have confirmed that the RNA-based vaccines show sufficient protection against the variants.
In the U.K. trial, efficacy of 2-dose Pfizer vaccine was 87.9% against the Delta variant and 93.4% against the Alpha variant; 2-dose AstraZeneca showed 59.8% efficacy against the Delta variant and 66.1% against the Alpha variant.
According to the data from clinical studies, the efficacy of the Novavax vaccine was 90% in the UK with circulation of the Alpha variant and 60% in South Africa with circulation of the Delta variant. The efficacy of the Johnson & Johnson vaccine was 72% in the US and 57% in South Africa.
Breakthrough infection rarely occurred. However, when looking at the risk of severe disease and hospitalization, the current vaccines seem to offer protection against developing severe COVID-19.
GVN Perspective: Should the Global Community Be Concerned About the South African Variant? – February 23, 2021
GVN Perspective: Update on SARS-CoV-2 Variants – February 5, 2021
GVN Perspective: Emergence and Global Spread of SARS-CoV-2 Variants – January 26, 2021