Biopharmaceutical company CureVac NV of Tübingen, Germany has released the interim results of its Phase 1 clinical trial on its experimental CVnCoV vaccine COVID-19. The vaccine, which was given to more than 250 healthy adults 18 to 60 years of age, is based on messenger ribonucleic acid (mRNA) technology.1 2
Unlike traditional vaccines, mRNA vaccines “introduce an mRNA sequence (the molecule which tells cells what to build), which is coded for a disease specific antigen,” wrote Rishma Parpia in an article in The Vaccine Reaction earlier this year.3 She added:
Once produced within the body, vaccine developers say the antigen is recognized by the immune system and stimulates a strong inflammatory response to produce antigens to fight the pathogen. Messenger RNA vaccines are faster and cheaper to produce than traditional vaccines and do not utilize any parts of the pathogenic virus or bacteria.3
According to a press release by CureVac, the CNnCoV vaccine was “generally well tolerated across all tested doses (2-12µg) and induced strong binding and neutralizing antibody responses in addition to first indication of T cell activation.” Trial participants were vaccinated intramuscularly with two doses 29 days apart. These included doses of two, four, six, eight and 12 milligrams (µg). Each dose level was given to groups consisting of up to 10 participants who had previously tested positive for the SARS-CoV-2 virus that can cause COVID-19.1
“We are very encouraged by the interim Phase 1 data. It represents a critical milestone in our COVID-19 vaccine program and strongly supports the advancement of our vaccine candidate,” said Dr. Franz-Werner Haas, CEO of CureVac. “Following further data readouts and discussion with regulatory authorities, we remain fully committed and on track to initiate a pivotal Phase 2b/3 trial before the end of 2020.”1
While CureVac reported that it observed no “serious adverse events” related to the CVnCoV vaccine, the company noted that some of the trial participants who received doses of 12 µg experienced Grade 3 adverse events mostly after being injected with the second dose. These reactions included fatigue, headache, chills, muscle pain and fever. CureVac reported that the reactions were “transient” and usually resolved within 24 to 48 hours.1
A Grade 3 adverse event is defined by the U.S. Department of Health and Human Services (HHS) as, “severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self care” such as “bathing, dressing and undressing, feeding self, using the toilet, taking medications.” In other words, a Grade 3 adverse event is serious. It is only one grade removed from “life-threatening” (Grade 4) and just two grades from “death” (Grade 5).4 5
CureVac is currently negotiating a deal to provide the European Union (EU) with 225 million doses of CNnCoV, with an option to supply EU countries with an additional 180 million doses, for a total of 405 million doses once the vaccine is approved by European regulatory authorities.2 6
1 Press release. CureVac : CureVac Reports Positive Interim Phase 1 Data for its COVID-19 Vaccine Candidate, CVnCoV. CureVac Nov. 2, 2020.
2 Taylor NP. CureVac links COVID-19 vaccine to immune response, setting it up to enter pivotal trial. Fierce Biotech Nov. 2, 2020.
3 Parpia R. Moderna to Use New mRNA Technology to Develop Coronavirus Vaccine. The Vaccine Reaction Feb. 12, 2020.
4 Cáceres M. A Grade 3 Vaccine-Related Adverse Event is Serious. The Vaccine Reaction July 26, 2020.
5 U.S. Department of Health and Human Services. Common Terminology Criteria for Adverse Events (CTCAE). Nov. 27, 2017.
6 Saigol L. CureVac and EU in advanced talks for 225 million Covid-19 vaccine doses. Market Watch Aug. 20, 2020.