A new study of healthcare workers in the United Kingdom shows that populations infected with SARS-CoV-2 during waves of different variants carry distinct immune memory, which may lead to differential protection against future variants of concern. The results could help inform selection of the variant spike sequences to serve in second generation vaccines against SARS-CoV-2. "This appears a more complex choice than simply opting for the most concerning variant at any given time," the authors say. COVID-19 vaccine programs currently use prototypic Wuhan Hu-1 sequence. Throughout the COVID-19 pandemic, people have been exposed to different types of SARS-CoV-2 antigens, either by vaccination or natural infection. A challenge in the field is to understand whether different antigen exposure combinations are associated with the same quality, quantity and durability of immunity and ability to cross-protect against other variants of concern. Catherine Reynolds et al. studied a cohort of UK healthcare worker (HCWs) followed since March 2020. In this group, they evaluated the impact of prior Wuhan Hu-1 or B.1.1.7 strain infection on the quality and quantity of immune responses against other variants of concern following COVID-19 vaccination with the Pfizer-BioNTech vaccine. The authors report an overall reduction in protection against variants of concern in vaccinated individuals previously infected with B.1.1.7 when compared to vaccinated individuals previously infected with the ancestral strain. The results demonstrate that the sequence of variant of concern to which someone is first exposed will influence immunogenicity profiles over time, pointing to additional considerations for vaccine development.
Heterologous infection and vaccination shapes immunity against SARS-CoV-2 variants
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