China’s new Covid vaccine candidate is 79% effective against Delta, company says

The SCB-2019 vaccine candidate shows 67 per cent efficacy against coronavirus infections of any severity caused by any strain, according to the study

Studies carried out for a new Covid-19 vaccine made by China’s Clover Biopharmaceuticals revealed it to have an efficacy of 79 per cent against the highly infectious Delta variant.

The protein-based vaccine candidate, known as SCB-2019, was also found to be 67 per cent effective overall against coronavirus infections of any severity and caused by any strain, said a statement by the company on Wednesday, citing a study it carried out.

SCB-2019 was also 92 per cent effective against the Gamma variant and 59 per cent effective against the Mu variant, according to the study.

Collectively, these three strains comprised “73 per cent of all strains identified in the study,” it said.

“We are pleased that SCB-2019 has successfully demonstrated efficacy against the globally dominant Delta strain and other concerning variants,” Clover’s chief executive officer Joshua Liang said in the statement.

“It is the first vaccine candidate to demonstrate significant efficacy against all three of these variants. Differences in vaccine efficacy across variant strains are driven by the unique mutation profiles of each variant, which can make some strains more transmissible and/or virulent than others and may enable immune escape,” said the company.

Clover, which has a deal to supply about 414 million doses of its coronavirus vaccines through the global vaccine sharing scheme of Covax, will submit the trial data for conditional approval to the World Health Organisation and regulators in China and Europe in the last quarter of this year.

The company received a funding of $328m from the Coalition for Epidemic Preparedness Innovations (CEPI) for the development of the vaccine. CEPI had earlier backed the AstraZeneca and Moderna Covid vaccines.

The pharmaceutical company enrolled over 30,000 adults from 31 sites in the Philippines, Brazil, Columbia, South Africa and Belgium for its clinical trial, which had candidates receiving randomised doses of SCB-2019 or a placebo in a two-dose regimen, administered 21 days apart.

The trial was carried out between 28 April and 10 August this year, where scientists tested the efficacy, safety and immunogenicity of the vaccine, according to the organisation.

An independent Endpoint Adjudication Committee adjudicated on a total of 207 symptomatic Covid-19 cases that were reported at least two weeks after the second dose in the large trial. Those participating in the trial had not contracted the coronavirus infection earlier.

Of the total cases, 52 were from a vaccinated group, while the remaining 155 formed the placebo group.

The trial found there to be no cases of hospitalisation due to Covid and no cases of severe disease in the vaccine group, resulting in 100 per cent efficacy against hospitalisation and severe coronavirus infections.

The vaccine has 83.7 per cent efficacy against moderate-to-severe coronavirus infections against any strain. Three deaths, however, were reported to have occurred in the placebo group, according to the study.

Clover said the enrollment of elderly participants in the trial was limited as the inoculation campaign for vaccinating the elderly population had already started in countries where Clover was recruiting participants.

It added that all five cases of Covid in participants of 65 years of age or older occurred in the placebo or non-vaccine group.

Of the total participants, about 18 per cent had comorbidities, but the trial saw no differences in vaccine efficacy in participants with or without comorbidities.