Pirbright research shows that immunity to SARS-CoV-2, the virus that causes COVID-19, decreases over time after vaccination, but that booster vaccinations can help restore immunity and help the immune system recognise new variants of the virus, including Omicron.
Vaccination against SARS-CoV-2 has been pivotal in protecting people across the world, especially older adults and the vulnerable, preventing serious disease and hospitalisations.
But since the vaccination programme began there have been uncertainties on exactly how long that protection lasts and how effective vaccines are against new emerging variants.
Scientists at the Institute led a study in collaboration with Imperial College London, the UK Health Security Agency, and the University of Surrey’s School of Veterinary Medicine to understand the immune response in individuals aged 70-89 who had received the Pfizer-BioNTech vaccine.
This particular vaccine works by triggering the immune system to create Y-shaped proteins, known as antibodies, that can stick to the viral spike proteins found on the surface of the coronavirus. If a person is infected with SARS-CoV-2 the antibodies attach to these spike proteins preventing the virus from binding to, and entering the human cell. Antibodies also act as a beacon to alert the immune system to destroy the virus; however, scientists were unsure on how long this protection lasts.
Study participants all received two doses of the vaccine three weeks apart. Their antibody levels were measured at three and 20 weeks following the second dose. The results suggested that immunity decreased 20 weeks after vaccination which could leave individuals susceptible to infection.
Researchers also investigated the ability of antibodies to recognise over 20 different variants, including Alpha, Beta, Delta, and Omicron. Results highlighted that some SARS-CoV-2 variants can partially or wholly avoid the immune response that was created by vaccination. However, boosting with a third dose of the Pfizer-BioNTech vaccine improved the immune system’s ability to recognise and neutralise those variants. This highlights the importance of booster vaccines.
Dr Dalan Bailey, Head of the Viral Glycoproteins group at Pirbright said: “Research comparing immune responses to different SARS-CoV-2 variants and understanding the role of different mutations is vital in the management of the COVID-19 pandemic and in predicting the outcome of new variants. This is especially important in older adults where the antibody response may be different and where SARS-CoV-2 has caused so many hospitalisations and deaths”.
This work was supported by the Medical Research Council funded G2P-UK National Virology Consortium; G2P-UK; A National Virology Consortium to address phenotypic consequences of SARS-CoV-2 genomic variation, The Pirbright Institute’s BBSRC institute strategic programme grant and the European Union’s Horizon 2020 Research and Innovation programme under grant agreement No 773830: One Health European Joint Programme.