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Trial Shows Covid-19 Vaccine Safety, Immune Response



3 Nov. 2020. First results from an early-stage clinical trial show an RNA-based vaccine to prevent Covid-19 infections is safe and produces a complex immune response. Findings from the trial sponsored by CureVac N.V., a biotechnology company in Tübingen, Germany, are reported on the company’s web site and are not yet peer reviewed.

CureVac creates vaccines with a technology producing messenger RNA, the nucleic acids that transcribe an individual’s genetic code in DNA into amino acids that instruct cells in the body to produce proteins. With this technology, the company develops cancer immunotherapies and vaccines for infectious diseases. The platform is based on research by CureVac’s scientific founder Ingmar Hoerr in the 1990s, which assembles the usually unstable messenger RNA molecules into stable therapeutics.

The Coalition for Epidemic Preparedness Innovations, or CEPI, an international consortium that funds vaccines for infectious diseases, is a co-sponsor of the trial. CEPI supports in particular vaccines not financially attractive for pharmaceutical companies. In February 2019, CEPI awarded CureVac a $34 million contract to advance the company’s mobile messenger RNA manufacturing platform that formulates vaccines into lipid, or natural oil, nanoscale particles. On 31 January of this year, CEPI extended that work to cover development of a vaccine to protect against infections from the SARS-CoV-2 coronavirus.

The early-stage clinical trial is enrolling 284 healthy volunteers at four sites in Belgium and Germany, who receive two doses of CureVac’s vaccine, code-named CVnCoV, or a placebo, 28 days apart. The study team is looking primarily for adverse effects from the vaccine, at various doses, from 2 to 12 micrograms. The researchers are also looking for immune responses produced by vaccine recipients, in both the antibodies and T-cells generated by participants. Participants are checked periodically for adverse effects up to four weeks after vaccination, and eight weeks for immune responses, then tracked for 13 months for long-term effects.

CureVac says CVnCoV is generally well tolerated by more than 250 trial participants at all dose levels. At the highest dose, 12 micrograms, serious adverse effects occurred requiring medical attention, including fatigue, headache, chills, muscle pain, and fever. The company says these more serious effects occurred after the second injection, and were resolved within 24 to 48 hours.

According to CureVac, the findings also show CVnCoV invokes an immune response in recipients from both antibodies and T-cells. The company says participants receiving CVnCoV all dose levels produced binding and neutralizing antibodies. At the 12 microgram dose, the concentration of neutralizing antibodies in blood plasma is equivalent to the levels of people with serious Covid-19 infections. In addition, early results show 12 microgram recipients produce T-cells in the immune system, that could provide more comprehensive protection.

“These initial data,” says Mariola Fotin-Mleczek, CureVac’s chief technology officer in a company statement, “show a robust and highly efficient immune response to our natural mRNA-based CVnCoV vaccine candidate, including antibody and initial T cell responses at the level of a relevant panel of symptomatic convalescent patients.” The company says it plans to submit the findings for publication in the upcoming weeks.

The findings, says CureVac, support proceeding with the 12 microgram dose in a mid- and late stage clinical trial planned for next year. A mid-stage trial of CVnCoV enrolling nearly 700 participants, is already underway in Peru and Panama.

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