Antibody Response
The interval between vaccine doses for Pfizer/BioNTech (mRNA) vaccine was lengthened in the UK to accelerate population coverage with a single dose, and was strongly opposed by the BMA et al (the longer gap had not been tested).
JCVI were very confident in their judgement (implemented wef 31 Dec) and new research has backed their educated hunch: a 10+ week gap may have resulted in a stronger response to the second dose.
The preprint from the
PITCH study* suggested that after a priming first dose of that vaccine, there was a marked decline in neutralising antibody responses over a 10-week period, but that T-cell responses were well-maintained. As a single dose of vaccine is known to offer significant protection, this suggests that T cells may be an important part of the protection from illness mechanism.
It found that following the second dose, the longer interval resulted in
twice as high neutralising antibodies against all variants of the virus, including the Delta variant, compared with the shorter dosing interval.
* Led by the Universities of Oxford and Liverpool - 503 healthcare workers.
An expert commented: ". . . vaccinologists will not be surprised by the findings of this study".
Edit: The takeaway is, younger ones: bear in mind that the shorter the gap between jabs the lower overall protection you'll develop. Balanced against that, protection of only 33% after first jab improves to (say) 80% (figures vary between vaccine, protection 'gainst what and within a confidence interval). So getting the second jab at less than 10 weeks maybe one sweet now rather than two later.