- Chinese drugmaker Clover Biopharmaceuticals said Wednesday its experimental coronavirus vaccine prevented COVID-19 in a large Phase 3 trial, reporting efficacy of 67% against disease of any severity and 85% against moderate-to-severe disease.
- Clover is preparing to seek conditional authorization with global regulatory agencies in the fourth quarter and is targeting a launch by the end of 2021. Headquartered in Chengdu, China, the company has received support from international health organizations and has arranged to sell more than 400 million doses for global distribution.
- While wealthy nations have achieved relatively high vaccination rates because of early deals with Pfizer, Moderna and other companies that developed the first vaccines, immunization in middle- and low-income countries has lagged because those same agreements dried up initial supplies. If approved, Clover's shot could help efforts to rein in the COVID-19 pandemic globally.
Worldwide, 2.4 billion people have been fully vaccinated, and 3.3 billion have received at least one dose of a two-dose regimen like Pfizer's, Moderna's and AstraZeneca's, according to the World Health Organization. Rates are much lower in low- and middle-income countries of Africa and central Asia, however, limiting the ability of public health officials to curb the virus' spread and prevent sickness and death. Moreover, unchecked spread raises the risk that more infectious or more lethal strains could continue to emerge.
Clover partnered early on with the Coalition for Epidemic Preparedness Innovations to ensure global distribution, signing a deal that could bring in $328 million in grant funding based on equitable access agreements which helped spur early development. The company also agreed in advance with the vaccine alliance GAVI to sell more than 400 million doses to a global vaccine pool that has also made deals with Pfizer, Moderna, AstraZeneca, Johnson & Johnson and three other vaccine makers.
Those early bets appear to have paid off with data from Clover's Phase 2/3 SPECTRA trial.
"As a result of CEPI's partnership with Clover, this vaccine is poised to play a significant role in protecting those most at risk from COVID-19, wherever they are in the world," CEPI CEO Richard Hatchett said in a statement.
Conducted in the Philippines, Colombia, Brazil, South Africa and Belgium, the trial enrolled 30,000 volunteers 18 years and older and randomized half to receive two shots of the vaccine spaced three weeks apart or placebo injections. Trial researchers began measuring COVID-19 cases beginning 14 days after the second shot.
At the primary analysis, researchers counted 52 cases of COVID-19 among patients who received the vaccine and 155 in the placebo arm, calculating an overall efficacy of 67%. Against the delta variant, the estimated efficacy was better, at 79%, although there was a higher degree of statistical uncertainty. Efficacy against moderate-to-severe cases of any variant was found to be 84%, and among delta cases it was 82%, Clover said.
Delta infections represented 38% of cases reported in SPECTRA that were sequenced, while the more recently identified mu variant accounted for 25% of cases, Clover said. The gamma and beta variants were behind 9% and 8% of the cases, respectively.
Local and systemic adverse events were similar to the types seen with other vaccines and not significantly elevated when compared to those seen with placebo recipients. Clover said the rates were lower than many other vaccines. Rare safety events observed with other coronavirus vaccines, such as myocarditis and Guillain-Barré syndrome, only emerged after approval and millions of people were vaccinated.
Clover's vaccine is a protein manufactured to resemble the SARS-CoV-2 virus' signature spike protein and stimulate a lasting immune response that can repel infections of the actual virus. The immune response is further amplified by the use of a chemical called an adjuvant manufactured by biotech Dynavax.
Dynavax shares rose 27% following Clover's announcement.