Question explored with the scientific record
Conversation so far
- 1 Is this year’s flu jab worth it in the uk
- 2 How does this year's UK flu vaccine compare to past vaccine effectiveness?
Answered on this page ↓
How does this year's UK flu vaccine compare to past vaccine effectiveness?
The short version: no retrieved study tests this year's UK flu vaccine against past seasons, so there is no evidence to compare.
The retrieved studies cover UK flu vaccine effectiveness from 2011-12 through 2015-16, but none test this year's formulation or compare it to prior years in a single analysis [1, 2]. The closest is the 2011-12 UK study showing 23% adjusted effectiveness against A(H3N2) and 92% against influenza B, with significant waning over the season [1]. The 2015-16 English children's study found 33% effectiveness against hospitalization overall, with LAIV at 42% and IIV at 29% [2]. These are single-season snapshots, not comparisons.
The evidence that does exist shows wide year-to-year variation driven by antigenic match. The 2011-12 UK study documented 20.6% of circulating H3N2 viruses with reduced reactivity to the vaccine strain [1]. A 2018-19 Israeli study found essentially zero effectiveness against H3N2 overall (-3.5%) when the dominant circulating clade differed from the vaccine clade [3]. A meta-analysis across multiple seasons found pooled H3N2 effectiveness of 33% versus 61% for H1N1pdm09 [4].
| Season | UK VE against A(H3N2) | Source |
|---|---|---|
| 2011-12 | 23% (95% CI -10 to 47) | [1] |
| 2015-16 (children, hospitalization) | 33% (95% CI 2 to 55) | [2] |
The comparison the asker wants — this year versus past years — simply does not appear in the retrieved literature. No study tracks VE across multiple UK seasons in a consistent design. The year-to-year variation is large enough that last season's number tells you little about this season's.
My call: there is no evidence to compare this year's UK flu vaccine effectiveness to past seasons. The retrieval surfaced no multi-season UK comparison. Confidence: not clear — the question cannot be answered from what was retrieved.
Sources used 4
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Vaccine effectiveness of 2011/12 trivalent seasonal influenza vaccine in preventing laboratory-confirmed influenza in primary care in the United Kingdom: evidence of waning intra-seasonal protection
The 2011/12 trivalent seasonal influenza vaccine provided low overall protection (23% adjusted VE) against influenza A(H3N2) infection in UK primary care with significant intraseasonal waning (VE decline from 53% to 12% by time since vaccination), but high protection (92%) again…
DOI: 10.2807/ese.18.05.20389-en -
Influenza vaccine effectiveness against hospitalisation due to laboratory-confirmed influenza in children in England in the 2015–2016 influenza season – a test-negative case–control study
In 2015-2016 England, influenza vaccination in vaccine-eligible children 2-16 years provided 33.4% adjusted effectiveness against laboratory-confirmed influenza hospitalisation, with LAIV at 41.9% and IIV at 28.8%.
DOI: 10.1017/s0950268819000876 -
Predominance of a Drifted Influenza A (H3N2) Clade and Its Association with Age-Specific Influenza Vaccine Effectiveness Variations, Influenza Season 2018–2019
The 2018-2019 Israeli influenza season was dominated by drifted influenza A(H3N2) clade 3C.3a; adjusted vaccine effectiveness was -3.5% overall and 45% in adults aged ≥45 years, with age-group estimates not statistically significant.
DOI: 10.3390/vaccines8010078 -
Influenza Vaccine Effectiveness: Defining the H3N2 Problem
This narrative review synthesizes evidence that influenza vaccine effectiveness is consistently lower against H3N2 than H1N1pdm09 or type B, and attributes this to viral antigenic evolution, egg-adaptive mutations, and host immunity factors.
DOI: 10.1093/cid/ciz411