What is CureVac's COVID-19 vaccine, and why it failed to cross 50% threshold in efficacy

Germany’s COVID-19 vaccine made by CureVac has failed to cross the minimum 50 percent efficacy threshold deemed necessary to be accepted as a viable vaccine against COVID-19 disease. The company said that the final trial results of its CVnCoV vaccine had an efficacy rate of just 48 percent, far lower than those developed by mRNA rivals BioNTech/Pfizer and Moderna. The outcome had been expected after poor interim data were released earlier this month. Why is it relevant? CureVac’s CVnCoV vaccine was considered important for many reasons.

• First, it would have helped bridge the gap of vaccine shortage in the European Union. The regional grouping has secured up to 405 million doses, AFP reported.
• Second, the CVnCoV, an MRNA vaccine can be stored at standard refrigerator temperature, unlike the first-generation Pfizer and Moderna vaccines which require super-cold freezers.
• Third, CureVac’s vaccine also requires a lower dosage of just 12 microgrammes, compared to 30 microgrammes for BioNTech and 100 for Moderna, allowing for faster and cheaper mass production. All these factors could possibly give CureVac an edge in poorer or warmer countries, AFP said.

But the low efficacy rates mean getting approval from regulators, as well as the WHO, would be a challenging task, that if CureVac’s application is even considered. The Tuebingen-based company has shared its data with the European Medicines Agency (EMA), which will now decide if the vaccine is good enough to be greenlit. Why the low efficacy? Scientists have said the weaker-than-hoped results may be down to the lower dosage, or even CureVac’s recipe, which unlike its rivals uses an unmodified form of messenger RNA. The company in part blamed “the unprecedented context of 15 strains circulating” among the trial volunteers, as well as varying responses across age groups. The Covid vaccines developed by Germany’s BioNTech in partnership with US giant Pfizer and by US firm Moderna — based on the same novel messenger RNA technology — were approved earlier on in the pandemic after showing around 95 percent efficacy. Their trials only had to contend with the original strain of the virus. However, recent studies indicate that both (Pfizer and Moderna) vaccines also offer strong protection against the newer, more contagious variants. If the multiple strains are the reason for low efficacy, it also reflects poorly on the vaccine given that the spread of mutant variants like Delta Plus is rising. The second reason that CureVac gave for its poor efficacy results is that the CVnCoV vaccine did slightly better among people aged 18 to 60 than among older ages, with efficacy climbing to 53 percent. Among that same 18-60 age group, the vaccine offered 100-percent protection against hospitalisation and death. Is there any silver lining for CureVac? Yes. Despite the poor efficacy results, there are a few positives for CureVac’s COVID-19 vaccine. Given the severity of the COVID-19 disease, the WHO has set a 50 percent threshold of efficacy for COVID-19 vaccines. It has said that a COVID-19 vaccine with only 50 percent efficacy is still worth using. The CureVac vaccine has shown a higher efficacy (53 percent) among the 18 to 60 age group. This means that the vaccine could still be considered for that age group. In a statement, chief executive officer Franz-Werner Haas said “CVnCoV demonstrates a strong public health value” for people aged 18 to 60 “which we believe will be an important contribution to help manage the COVID-19 pandemic and the dynamic variant spread”. Though the company’s share price fell by nearly 10 percent in after-hours trading following the efficacy results were made public, CureVac believes it has advantages over mRNA competitors. Another positive is there are no safety concerns with the CureVac vaccine. CureVac’s late-stage Phase 2b/3 trial involved some 40,000 people in 10 countries in Europe and Latin America. Of those, 228 contracted the coronavirus. CureVac said in May that independent analysis “found no safety concerns” with its two-dose vaccine. What do we know about CureVac? For those of you who don’t know much about Curevac, the company was founded in 2000 by mRNA pioneer Ingmar Hoerr and is backed by Dietmar Hopp, the German billionaire behind software behemoth SAP. The company was in news last year when former US president Donald Trump had sought exclusive US access to any CureVac vaccine, a claim both sides strenuously denied. Shortly after, the German government took a 23-percent stake in CureVac for 300 million euros. The CureVac vaccine has since then been referred to as the German vaccine. What’s next: The company is already working on a second-generation COVID-19 vaccine for which it has teamed up with pharma giant GSK. Early results on rats have been promising, it said. Clinical testing on humans is set to begin in the third quarter of 2021. With inputs from AFP