FIVE OF THE LEADING CORONAVIRUS VACCINE CANDIDATES

 More than two dozen experimental coronavirus vaccines are already in human trials from New York to New Delhi, according to the World Health Organization.

Some of the frontrunners were first given to small groups starting around March, and now several are being tested on thousands of volunteers in large-scale phase 3 clinical trials.

Phase 3 testing breaks subjects into randomized groups — those who receive the experimental vaccine, likely with one or two injections spaced several weeks apart, and those who get a placebo, possibly in the form of salt water.

If researchers can show the vaccine is preventing disease without serious side effects, they can ask for regulatory approval to start making and licensing it for mass consumption.

AstraZeneca/Oxford University: The vaccine, dubbed AZD1222, combines genetic material from coronavirus with an andenovirus found in chimps. It’s now in phase 3 trials after phase 1/2 data showed a strong immune response with only minor side effects, such as headache and fatigue, researchers said. The results, published in the British medical journal The Lancet, said patients who received a second dose fared even better. The vaccine project received a promise of “up to $1.2 billion” in support from the U.S. government in May.

Pfizer/BioNTech: The vaccine, called BNT162b2, began a phase 3 trial July 27 that’s expected to enroll 30,000 participants in the U.S. and abroad. In earlier trials, the vaccine generated antibodies against the coronavirus as well as “concurrent” immune cells called T cells, researchers said. If the phase 3 trial goes well, the companies plan to seek regulatory authorization “as early as October 2020” and supply up to 100 million doses by the end of 2020.

John Burkhardt, Pfizer's senior vice president of drug safety research and development, speaks at a news conference in Groton, Conn. (Stew Milne/AP)

Moderna/National Institutes of Health: The vaccine, named mRNA-1273, also started a phase 3 trial July 27 that plans to enroll 30,000 people. A prior phase 1 trial found it was safe, generally well-tolerated and able to induce antibodies with high levels of virus-neutralizing activity, the NIH said. Once injected, the vaccine directs the body’s cells to express the “spike protein” that coronavirus uses to invade cells. The harmless protein then trains the immune system to create antibodies against the spike before an actual coronavirus infection. The U.S. government has underwritten the project with nearly $1 billion. 

Johnson & Johnson: The vaccine, called Ad26.COV2.S, started phase 1/2 clinical trials July 15 that are designed to test the intramuscular shot’s safety and immunogenicity at two dose levels. The company is aiming to begin phase 3 trials in September. It previously received $456 million from the U.S. government to support vaccine development under an existing partnership with its Janssen Vaccines group. On Aug. 5, it announced government officials agreed to pay $1 billion for 100 million doses if the investigational vaccine is approved by the FDA or receives Emergency Use Authorization.

Novavax: The vaccine, known as NVX-CoV2373, uses nanoparticle technology to get a patient’s body to generate antibodies. The antibodies then block the binding of coronavirus spike protein. Data released Tuesday from a phase 1 trial reported robust antibody responses superior to that seen in patients who’ve recovered from COVID-19. The Maryland-based company announced July 7 it was awarded $1.6 billion by the federal government to complete its phase 3 trial and establish large-scale manufacturing to start delivering 100 million doses as early as late 2020.