Effect of Delta variant on viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK.
Nat Med
; 27(12): 2127-2135, 2021 12.
Article
in English
| MEDLINE | ID: covidwho-1469978
Preprint
This scientific journal article is probably based on a previously available preprint. It has been identified through a machine matching algorithm, human confirmation is still pending.
See preprint
This scientific journal article is probably based on a previously available preprint. It has been identified through a machine matching algorithm, human confirmation is still pending.
See preprint
ABSTRACT
The effectiveness of the BNT162b2 and ChAdOx1 vaccines against new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections requires continuous re-evaluation, given the increasingly dominant B.1.617.2 (Delta) variant. In this study, we investigated the effectiveness of these vaccines in a large, community-based survey of randomly selected households across the United Kingdom. We found that the effectiveness of BNT162b2 and ChAdOx1 against infections (new polymerase chain reaction (PCR)-positive cases) with symptoms or high viral burden is reduced with the B.1.617.2 variant (absolute difference of 10-13% for BNT162b2 and 16% for ChAdOx1) compared to the B.1.1.7 (Alpha) variant. The effectiveness of two doses remains at least as great as protection afforded by prior natural infection. The dynamics of immunity after second doses differed significantly between BNT162b2 and ChAdOx1, with greater initial effectiveness against new PCR-positive cases but faster declines in protection against high viral burden and symptomatic infection with BNT162b2. There was no evidence that effectiveness varied by dosing interval, but protection was higher in vaccinated individuals after a prior infection and in younger adults. With B.1.617.2, infections occurring after two vaccinations had similar peak viral burden as those in unvaccinated individuals. SARS-CoV-2 vaccination still reduces new infections, but effectiveness and attenuation of peak viral burden are reduced with B.1.617.2.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
SARS-CoV-2
/
COVID-19
/
Vaccine Efficacy
/
BNT162 Vaccine
/
ChAdOx1 nCoV-19
Type of study:
Experimental Studies
/
Observational study
/
Randomized controlled trials
Topics:
Vaccines
/
Variants
Limits:
Adolescent
/
Adult
/
Humans
/
Middle aged
/
Young adult
Country/Region as subject:
Europa
Language:
English
Journal:
Nat Med
Journal subject:
Molecular Biology
/
Medicine
Year:
2021
Document Type:
Article
Affiliation country:
S41591-021-01548-7
Similar
MEDLINE
...
LILACS
LIS