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# Sanofi/GSK Delay Covid Vaccine Over Disappointing Data
- URL: https://www.fdaweb.com/sanofi-gsk-delay-covid-vaccine-over-disappointing-data/
- Published: 2020-12-11T12:00:00.000Z
- Updated: 2026-09-14T16:39:51.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5148289

Sanofi and GlaxoSmithKline have announced a delay in their Covid-19 vaccine program to improve immune response in older adults. “Phase 1/2 study interim results showed an immune response comparable to patients who recovered from Covid-19 in adults aged 18 to 49 years, but a low immune response in older adults likely due to an insufficient concentration of the antigen,” the companies say.

Sanofi and GSK say they plan to develop the adjuvanted recombinant protein-based COVID-19 vaccine with an improved antigen formulation. A new Phase 2b study is expected to start 2/2021, which will include a proposed comparison with an authorized Covid-19 vaccine.  
If data are positive, a global Phase 3 study could start in second quarter 2021, they say. “Positive results from this study would lead to regulatory submissions in the second half of 2021, delaying the vaccine’s potential availability from mid-2021 to fourth quarter 2021.

Meanwhile, Moderna reports that the U.S. government has exercised its option to purchase an additional 100 million doses of its vaccine, which goes before an advisory committee 12/17, bringing its confirmed order commitment to 200 million doses. Presumably, the larger order will make up for the loss of available vaccines from the Sanofi/GSK delay. The new order of 100 million doses will be delivered in the second quarter of 2021, assuming the company is granted an emergency use authorization after the committee meeting.