Sanofi and Britain’s GlaxoSmithKline said on Friday they will test their potential COVID-19 vaccine further after clinical trials showed an insufficient immune response in older people, delaying its potential launch until the end of next year.
The two companies said they planned to start another study next February, hoping to come up with a more effective vaccine by the end of 2021, in a blow to efforts to fight the pandemic.
The news comes as a disappointment for one of a crop of vaccines under development that rely on more conventional proven designs as the shot developed by Pfizer and BioNTech using breakthrough technology gets rolled out across Britain.
It is also a blow for many governments, including the European Union, the United States, Canada and Britain, which have booked hundreds of millions of doses of the shot as they struggle to tame the virus which has killed more than 1.5 million people and crushed economies.
Delays and additional trials are not unusual but the setback highlights the challenges in developing vaccines at record speed. It also underscores why governments have booked lots of different shots so they are not replying on just one.
Friday’s 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,” France’s Sanofi said.
“With this type of vaccine, the result is not a surprise, we know that more antigen is needed in older patients. But when in phase I and II, drugmakers test tolerance and one cannot test strong dosages,” said Jean-Daniel Lelievre, head of clinic immunology and infectious diseases at Henri-Mondor hospital in Creteil, France.
“I would think Sanofi and GSK will be able to improve their vaccine.”
Phase III studies were expected to start this month.
Sanofi said it would launch a phase 2b study in February of next year instead after a recent challenge study in non-human primates performed with an improved antigen formulation demonstrated better effects.
“The study will include a proposed comparison with an authorized COVID-19 vaccine,” the company said.
“If data are positive, a global Phase III study could start in Q2 2021. Positive results from this study would lead to regulatory submissions in the second half of 2021, hence delaying the vaccine‘s potential availability from mid-2021 to Q4 2021.”
The two companies said they had “updated governments and the European Commission where a contractual commitment to purchase the vaccine has been made.”
The Sanofi-GSK vaccine uses the same recombinant protein-based technology as one of Sanofi’s seasonal influenza vaccines. It will be coupled with an adjuvant, a substance that acts as a booster to the vaccine, made by GSK.
The Phase I/II study tested the safety, tolerability and immune response of the vaccine in 440 healthy adults across 11 investigational sites in the United States.
This week, Britain started deploying a vaccine that uses a breakthrough mRNA technology developed by Pfizer and BioNTech, jumping ahead of the rest of the world in the race. Canada gave the greenlight for the shot, too.
The data comes as a panel of outside advisers to the U.S. Food and Drug Administration on Thursday voted overwhelmingly to endorse emergency use of the Pfizer/BioNTech vaccine.
Rival developers AstraZeneca Plc and Moderna have also reported late stage data that shows their shots are effective at preventing the virus.
The French group is also working on another vaccine candidate to prevent COVID-19 with U.S. company Translate Bio which will rely on a different technology called mRNA, similar to the one developed by Pfizer and Moderna.
Phase I trials for this vaccine are expected to start this month.
Sanofi and GSK have scaled up manufacturing in order to be ready to produce up to one billion doses of their vaccine in 2021.
GSK is contributing adjuvants to two other COVID-19 vaccines projects, one with Medicago of Canada and the other with China’s Clover Biopharmaceuticals.