COVID-19 B.1.617.2 (delta) Variant, first detected in India, has contributed to a significant increase in the number of COVID cases and has inexorably spread all across the world.
The relative efficacy of BNT162b2 (Pfizer–BioNTech) and ChAdOx1 nCoV-19 (AstraZeneca) vaccines against this new variant was unclear
Vaccine efficacy against the delta symptomatic infection vs. the predominant variant infection (alfa or UK variant) was assessed over the period the delta variant started circulating.
Variants were identified by means of spike (S) gene sequencing. The data from all symptomatic COVID-19 cases sequenced in England was used to know the proportion of sick people and their vaccination status.
Single dose efficacy was significantly lower in people infected with the delta variant (30.7%) vs the alfa (48.7%). Pfizer–BioNTech and AstraZeneca outcomes were similar.
The complete vaccination scheme with Pfizer–BioNTech achieved 93.7% efficacy for the alfa and 88% with the delta.
For the complete AstraZeneca scheme, efficacy reached 74.5% for the alfa and 67% for the delta.
Read also: Large Differences between Focal and Diffuse Patterns of Stable CAD.
This drop in efficacy against the delta variant with the complete scheme is modest, though it does exist. The difference is significant with one single dose.
Conclusion
The complete scheme of Pfizer–BioNTech and AstraZeneca saw a slight drop in efficacy against the new delta variant, but still robust. The difference is important only in those who received one single dose. Therefore, it is vital to coordinate efforts to bring the complete scheme to term in the fight against this new variant.
Original Title: Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant.
Reference: Jamie Lopez Bernal et al. N Engl J Med. 2021 Aug 12;385(7):585-594. doi: 10.1056/NEJMoa2108891.
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