The race to get a Covid-19 vaccine has been subjected to a relapse, with Sanofi and GlaxoSmithKline delaying the launch of the vaccine until the end of next year and Australia abandoning the trial after participants returned false-positive HIV tests.

French company Sanofi and British company GSK said on Friday Their vaccine It failed to produce a robust immune response in the elderly due to a combination that actually meant the dose was too low. This would delay the expected launch – if the vaccine is approved by the regulators – to the last quarter of 2021, instead of the middle of the year as previously expected.

Hours earlier, the Australian government said a local vaccine would be dropped after several trial participants retested positive HIV even though they had not had the virus.

The setbacks were a reminder of the difficulties of rapidly producing vaccines, after several weeks advances in further trials have raised hopes that the epidemic will be brought under control in 2021.

Many rich countries have applied for many candidate vaccines, given the likelihood that not everyone proves that they are safe and effective.

Sanofi and GSK said early test results showed “a similar immune response in patients who recovered from Covid-19 in adults between the ages of 18 and 49, but the lowered immune reaction in the elderly was likely due to a lack of antigen concentration” – reference The molecule that stimulates the immune system to respond to the virus.

Researchers who studied why this happened found that the reagents used to measure the amount of antigen included in each dose gave incorrect readings, Sanofi told STAT News in Interview.

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Both companies said they were disappointed with the results. “Our goal now is to work closely with our partner Sanofi to develop this vaccine, with an improved antigen formulation, in order to make a beneficial contribution to the prevention of Covid-19,” said Roger Connor, President of GSK Global Vaccines.

Benny Ward, a visiting professor of pharmaceutical medicine at Kings College London, said Sanofi and GlaxoSmithKline are using an established technology that relies on boosting the vaccine material to induce an adequate immune response. Older adults are known to have fewer immune responses to these types of vaccines but this can be overcome, either by frequent injections, or by increasing the dose of the antigen at each dose.

Sanofi and GSK are two of the largest vaccine makers in the world, so their experience and use of current technologies, rather than the new messenger RNA approach used by Pfizer / BioNTech and Moderna, have raised hopes that they will become major suppliers.

The European Union has ordered 300 million doses of the Sanofi / GSK vaccine, while the United Kingdom has requested 60 million doses. The United States has a request for 100 million initial doses plus an option of 500 million. Covax, a partnership that aims to ensure vaccines reach the developing world, was set to receive 200 million.

In a sign that Sanofi was aiming to provide nearly a third of total Covax doses, Julia Heres García, Global Health and Gender Equality Officer at Oxfam, said the delay was “a bitter blow to poor countries”.

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The Australian vaccine was developed by the University of Queensland and the pharmaceutical company CSL, which has said it will do so No progress To phase II and III clinical trials due to concerns that the vaccine might interfere with HIV testing and erode public confidence.

They stressed that there was no possibility that the vaccine would cause HIV infection and that follow-up tests confirmed the absence of HIV in the trial participants.

The developers said the problems with using small portions of a protein from HIV in the production of the vaccine. They said that the participants in the trial developed antibodies to this protein, gp41, which interfered with some HIV tests.

CSL / UQ said the vaccine has created a robust immune response and has a strong safety profile, but important changes must be made to HIV testing procedures if the vaccine is to roll out.

Scott Morrison, Prime Minister of Australia, said abandoning the UQ / CSL vaccine would not delay the national vaccination program, as CSL may start manufacturing competing vaccines sooner.

The Australian government announced that it has purchased an additional 31 million doses of competing vaccines produced by AstraZeneca / University of Oxford and Novavax. It has already signed an agreement with Pfizer / BioNTech.

Australia plans to start its vaccination program from March, arguing that its success in quelling the spread of the virus means it has not had to speed up the process.

Covered by Laila Abboud