WHO: Take an interval of 8-12 weeks for Covishield doses

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The recommendation comes in the backdrop of the Indian regulator’s directive that the two doses of COVID-19 vaccine Covishield should be given only four to six weeks apart even though evidence from the clinical trials conducted by Oxford and AstraZeneca in the UK showed that the vaccine had only around 54% efficacy as compared to 79% if the gap is 12 weeks.

An expert panel of the World Health Organization has suggested an 8-12 week interval between two doses of the COVID-19 vaccine developed by University of Oxford and AstraZeneca. The vaccine is also manufactured by Serum Institute of India under the brand Covishield.

“In light of the observation that two-dose efficacy and immunogenicity increase with a longer interpose interval, WHO recommends an interval of 8 to 12 weeks between the doses. If the second dose is inadvertently administered less than 4 weeks after the first, the dose does not need to be repeated,” the WHO’s Strategic Advisory Group of Experts on Immunization (SAGE) said on Wednesday.

It added that if administration of the second dose is inadvertently delayed beyond 12 weeks, it should be given at the earliest possible opportunity and that another dose will not be required if the booster shot is given less than six weeks after the first despite the risk of lower efficacy.

AstraZeneca’s vaccine has generated significant controversies, especially over the last one week due to its lower efficacy against the mutant strain discovered in South Africa, following which the country has halted the use of the vaccine.

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