AstraZeneca/Oxford vaccine more effective with longer dose gap: study

(Reuters) – AstraZeneca and Oxford University’s COVID-19 vaccine is more effective when its second dose is given three months after the first, instead of six weeks, a peer-reviewed study published in The Lancet medical journal showed on Friday.

The study confirmed the Anglo-Swedish drugmaker’s findings from earlier this month that showed the vaccine had 76% efficacy against symptomatic coronavirus infection for three months after the first dose.

FILE PHOTO: A small shopping basket filled with vials labeled “COVID-19 – Coronavirus Vaccine” and a medical sryinge are placed on a AstraZeneca logo in this illustration taken November 29, 2020. REUTERS/Dado Ruvic/Ilustration

Efficacy was found to be at 81% with the longer interval of 12 weeks between the first and second dose, compared with 55% efficacy up to the six-week gap, according to the Lancet study, which backs British and WHO recommendations for longer intervals. (

Faced with a resurgence in infections and new, highly transmissible variants of the virus, many countries are hoping to broaden immunization by giving some protection to as many people as possible with a first dose, while delaying subsequent shots.

Reporting by Pushkala Aripaka in Bengaluru; Editing by Anil D’Silva


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