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June 10, 2020 — With more than 160 potential vaccines for COVID-19 under study, optimistic experts hope that a viable vaccine may be ready by the end of 2020.
Other experts caution that the timeline may be unrealistic. Only a small number of those vaccine candidates are being tested on people, and chances are many of the other projects won't survive beyond the laboratory stage.
Even so, vaccine experts point out that funding has been plentiful, many different approaches are under study, and collaborations between small firms developing the vaccines and large drug companies with the capacity to mass produce them all give reason for hope.
The U.S. said it would fund and conduct the phase III trials — the final step to determine how well the vaccine works and if it's safe — of three candidates: Moderna Inc., AstraZeneca, and Johnson & Johnson. The Moderna and AstraZeneca vaccines are already being tested in people, while J&J announced Wednesday it will begin its testing in the second half of July.
Here are some that are furthest along, with details on how the vaccine works.
Moderna. Moderna's vaccine, mRNA-1273, uses messenger RNA, an approach that does not require a virus to make the vaccine. The messenger RNA, or mRNA, carries instructions for making the spike protein, a key protein on the surface of the SARS-CoV-2 virus that allows the virus to enter cells when a person gets infected. When the vaccine with this instruction molecule is injected, it goes to the immune cells and instructs them to make copies of the spike protein, acting as if the cells have been infected with the coronavirus. Allowing other immune cells to develop ways to protect you gives immunity.
mRNA-1273 is in phase II of its clinical trial, designed to evaluate safety and effectiveness. Moderna, a biotechnology company working with the National Institute of Allergy and Infectious Diseases, intends to enroll 600 healthy volunteers equally divided into two age groups: 18 to 55, and 55 and older. They are already working on guidelines for phase III, with hopes of beginning in July 2020. Phase III, the final clinical trial phase, evaluates effectiveness in a much larger group and compares how well the vaccine works compared to a placebo. Moderna will test two different doses of the vaccine in the phase III trial. It requires two doses given 28 days apart. In mid-May, the company announced that all eight initial trial volunteers given two different dose amounts reached or surpassed the level of antibodies capable of neutralizing the virus.
University of Oxford and AstraZeneca. University of Oxford scientists are partnering with AstraZeneca to develop a COVID-19 vaccine made from a weakened version of a common cold virus, the adenovirus, taken from chimpanzees. The adenovirus is genetically altered so it can't reproduce itself. The vaccine is combined with genes of the spike protein to trigger production of vaccines against it that allows the immune system to destroy the SARS-CoV-2 virus.
A phase I/II clinical trial began in April in the U.K. to assess its safety and how well it works in more than 1,000 healthy volunteers 18 to 55 years old. Now, recruiting has begun for phase II/III trials, which will enroll up to 10,260 adults and children. For both phase II and III, volunteers will receive one or two doses of either the COVID-19 vaccine or a licensed vaccine that will be used as a control for comparison. In early June, Brazil, hard hit with COVID-19 cases, joined the clinical trials, planning to test 2,000 volunteers there.
After reaching a license agreement with Oxford University and others, AstraZeneca agreed to supply more than 2 billion doses globally, anticipating delivery of 400 million doses before the end of 2020.
Pfizer and BioNTech. The companies are testing four vaccines, each using messenger RNA, with a different combination of mRNA to targeted antigens (to produce antibodies). Called BNT162, volunteers in Germany and the U.S. have received the vaccine in a phase I/II clinical trial. This trial will evaluate the safety, ability to give immunity, and the optimal dose of the four candidates in a single and continuous study. Initially they are testing the vaccine on people 18 to 55. Once a given dose level is proven safe and effective, older adults will be immunized. Pfizer is predicting the production of millions of vaccine doses in 2020, increasing to hundreds of millions in 2021. Manufacturing sites have been identified both in the U.S. and elsewhere.
Inovio. Inovio's vaccine, INO-4800, is a DNA vaccine in phase I clinical trials, with 40 volunteers. The technology uses DNA designed to produce a specific immune response. A handheld smart device uses a brief electrical pulse to open small pores in the skin to deliver the vaccine. Once the DNA is inside a cell, it instructs it to make many copies of the artificial DNA, and this stimulates the body's natural immune response.
Results from the U.S. phase I trial are expected in June, and a phase II/III trial is expected then to begin. Human trials are also expected to begin this summer in China and South Korea. Multiple partners and collaborators are involved, including the Bill & Melinda Gates Foundation, the National Institutes of Health, and others.
CanSino. CanSino Biologics in Tianjin, China, is working with the Beijing Institute of Biotechnology on a coronavirus vaccine using a type of genetically altered adenovirus known as Ad-5. The platform has been used successfully to develop the Ebola virus vaccine.
In late May, researchers reported on results of the phase I safety study, in which 108 people got three doses (low, middle, high) of the vaccine. Most volunteers developed immune responses, but fewer had the neutralizing antibodies experts say are crucial to fight off the virus.
The company launched phase II in mid-April, with over 500 enrolled.
Johnson & Johnson. The company said it expected to start testing its vaccine in people in the second half of July. The vaccine combines genes from the coronavirus with a modified adenovirus. The first trial will include more than 1,000 healthy adults aged 18 to 55 and others 65 and older, and will take place in the U.S. and Belgium.
Other efforts. The Trump administration chose five companies for Operation Warp Speed, the national program to accelerate the development, making, and distribution of COVID-19 vaccines, treatments, and diagnostics. They are: Moderna, Johnson & Johnson, Merck, Pfizer and BioNTech, and AstraZeneca/Oxford University.
WebMD Health News Reviewed by Brunilda Nazario, MD, on June 10, 2020.
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Cite this: COVID-19 Vaccine: Latest Updates - Medscape - Jun 10, 2020.
