Vaccine subtype and dose interval determine immunogenicity of primary series COVID-19 vaccines in older people


Cell Reports Medicine

Contributing to research themes:

Age is the strongest determinant of COVID-19 mortality, and over 2 billion people have received primary series vaccination with BNT162b2 (mRNA) or ChAdOx1 (adenoviral vector). However, the profile of sustained vaccine immunogenicity in older people is unknown. Here, we determine spike-specific humoral and cellular immunity to 8 months following BNT162b2 or ChAdOx1 in 245 people aged 80–98 years. Vaccines are strongly immunogenic, with antibodies retained in every donor, while titers fall to 23%–26% from peak. Peak immunity develops rapidly with standard interval BNT162b2, although antibody titers are enhanced 3.7-fold with extended interval. Neutralization of ancestral variants is superior following BNT162b2, while neutralization of Omicron is broadly negative. Conversely, cellular responses are stronger following ChAdOx1 and are retained to 33%–60% of peak with all vaccines. BNT162b2 and ChAdOx1 elicit strong, but differential, sustained immunogenicity in older people. These data provide a baseline to assess optimal booster regimen in this vulnerable age group.

Author list:


  1. Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham B15 2TT, UK
  2. Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
  3. MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow G61 1QH, UK


Helen Parry1, Rachel Bruton1, Reni Ayodele1, Penny Sylla1, Graham McIlroy2, Nicola Logan3, Sam Scott3, Sam Nicol1, Kriti Verma1, Christine Stephens1, Brian Willett3, Jianmin Zuo1,, Paul Moss1