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expert reaction to preprint looking at the immune responses in over 80 year olds after one dose of either the Pfizer or AstraZeneca COVID-19 vaccine

A preprint, an unpublished non-peer reviewed study, looks at antibody generation and cellular immune responses in people over the age 80 5 weeks after a single dose of the Pfizer-BioNTech or Oxford-AstraZeneca COVID-19 vaccine.

This Roundup accompanied an SMC Briefing.


Prof Eleanor Riley, Professor of Immunology and Infectious Disease, University of Edinburgh, said:

“These data are reassuring in as much as they demonstrate robust immune responses in most elderly people after a single dose of either the Pfizer or the AstraZeneca vaccine. When linked to the PHE/ONS data showing reduced rates of COVID-19 infection, hospitalisation and death in this same age group after a single vaccination, these data help us to understand what level of immune response is likely to be protective, at least in the short term. Understanding how these laboratory data correlate with levels of ‘real world’ protection is really important for rapid assessment and roll-out of new vaccines: we can use these laboratory ‘correlates of protection’ to predict how the new vaccines will perform without having to go through the very lengthy process of phase three clinical trials.

“However, the much higher immune responses in people who have previously had COVID-19 shows that stimulating the immune system twice – in this case, through infection and then through vaccination – induces a much more potent (and likely much longer lasting) response. Assuming that a similar effect is seen after two vaccinations (as expected from the clinical trial data)  this really underscores the importance of having the second vaccination.”



Preprint (not a published paper): ‘Single vaccination with BNT162b2 or ChAdOx1 in older people induces equivalent antibody generation but enhanced cellular responses after ChAdOx1.’ by Parry et al is posted on the preprint server Preprints with The Lancet.



All our previous output on this subject can be seen at this weblink:



Declared interests

Prof Eleanor Riley: “Eleanor Riley is a member of the UKRI COVID-19 taskforce that approved funding for the UK-CIC.”

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