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Experimental coronavirus vaccine generated virus antibodies in small, early stage stu…


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Early data from Moderna Inc.’s COVID-19 vaccine, the first to be tested in the United States, showed that it produced protective antibodies in a small group of healthy volunteers, the company said Monday.

The data comes from eight people who took part in a 45-subject safety trial that kicked off in March. The Moderna vaccine is one of more than 100 under development intended to protect against the coronavirus that has infected more than 4.7 million people globally and killed over 315,000.

Moderna’s mRNA vaccine uses genetic material from the virus in the form of nucleic acid. That tells the human body how to make proteins that mimic viral proteins, and this should provoke an immune response. Overall, the study showed the vaccine was safe, and all study participants produced antibodies against the virus. 

An analysis of the response in the eight individuals showed that those who received a 100-microgram dose and a 25-microgram dose had levels of protective antibodies to fend off the virus that exceeded those found in the blood of people who recovered from COVID-19, the illness caused by the coronavirus.

The news, issued in a release by the U.S. biotechnology company, lifted shares of Cambridge, Mass.-based Moderna by 20 per cent. The stock later fell 1.6 per cent in extended trading after the company said it plans to sell $1.25 billion US in common stock to raise money for vaccine development and manufacturing.

Important not to ‘overstate’ results

“These are significant findings, but it is a Phase 1 clinical trial that only included eight people,” said Dr. Amesh Adalja, an infectious disease expert at the Johns Hopkins Center for Health Security, who was not involved in the study. “It was designed for safety, not for efficacy.”

The very early data offers a glimmer of hope for a vaccine among the most advanced in development.

Adalja said many glitches can occur between now and the time this vaccine is tested for efficacy in thousands of people. “What we do see is encouraging,” he said.

Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said in a Science Media Centre commentary on Monday that this was a Phase 1 study whose goal is to show the vaccine “is able to induce an antibody response and that the dose range is appropriate.” He was not involved with the study.

“The trial is not intended to show efficacy in reducing or preventing COVID19 disease, and it cannot be assumed on the basis of these results that it will do so. The Phase 3 trials will assess this, so it is important not to overstate these results.”

‘Fast-track’ status

Scientists are trying to understand what level of antibodies will ultimately prove protective against the coronavirus and how long that protection will last.

Moderna said the vaccine appeared to show a dose response, meaning that people with the 100-microgram dose produced more antibodies than people who got the lower dose.

The vaccine has gotten the green light to start the second stage of human testing. Last week, U.S. regulators gave the vaccine “fast-track” status to speed up the regulatory review.

In the Phase 2, or midstage, trial designed to further test effectiveness and find the optimal dose, Moderna said it will drop plans to test a 250-microgram dose and test a 50-microgram dose instead.

Reducing the dose required to produce immunity could help spare the amount of vaccine required in each shot, meaning the company could ultimately produce more of the vaccine.

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Maximizing number of doses

“In the context of a pandemic, we expect demand to far outstrip supply, and the lower the dose, the more people we expect to be able to protect,” said Moderna’s chief medical officer Tal Zaks.

The U.S. government in April placed a big bet on Moderna, backing its vaccine with $483 million from the Biomedical Advanced Research and Development Authority, a part of the U.S. Department of Health and Human Services.

The company said that grant will enable it to supply millions of doses per month in 2020 and, with further investments, tens of million a month in 2021 if the vaccine proves successful.

In May, Moderna struck a 10-year strategic collaboration with Lonza Group that over time will allow the manufacture of up to one billion doses a year.

“We are investing to scale up manufacturing so we can maximize the number of doses we can produce to help protect as many people as we can from SARS-CoV-2,” Moderna CEO Stéphane Bancel said, using the official name for the new virus.

Moderna said it expects to start a larger late-stage, or Phase 3, trial in July.

There are currently no approved treatments or vaccines for COVID-19, and experts predict a safe and effective vaccine could take 12 to 18 months to develop.

The most notable side-effects reported from the early testing of Moderna’s vaccine were three participants with flu-like symptoms following a second shot of the highest dose. The company said it believed the symptoms were an indirect measure of a strong immune response.

www.cbc.ca 2020-05-18 15:57:02

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