The company tested its vaccine on 10 adults between the ages of 56 and 70 and 10 elderly adults aged 71 and older, Moderna said. Each participant received two 100 microgram doses of the vaccine 28 days apart.
The volunteers produced neutralizing antibodies, which researchers believe are necessary to build immunity to the virus, and T-cells, Moderna said in its results, which have not yet been published in a peer-reviewed journal. Additionally, the antibodies that were produced were higher than those seen in people who have recovered from Covid-19.
The vaccine also appeared to be well tolerated, with no serious adverse events reported, the company said. Some patients reported fatigue, chills, headaches and pain at the injection site, though the majority of symptoms resolved within two days, the company said.
Shares of Moderna were up nearly 6% in intraday trading Wednesday. The company will hold a conference call at 4:30 p.m. ET to discuss the results.
The vaccine from Moderna is one of several in development to fight the coronavirus, which has infected more than 23.9 million people worldwide and killed at least 820,100, according to data compiled by Johns Hopkins University. There are more than 170 vaccines in development worldwide, according to the World Health Organization. At least 31 are in clinical trials, the WHO said.
U.S. health officials say there is no returning to “normal” until there is a vaccine.
Moderna’s experimental vaccine contains genetic material called messenger RNA, or mRNA, which scientists hope provokes the immune system to fight the virus. In May, the company released preliminary data that showed the vaccine produced antibodies in 45 healthy adults.
Scientists had previously cautioned that the phase one study was small, and the results may differ for other populations, including the elderly who generally mount a weaker immune response. The new data Wednesday will likely boost hopes that there could be a safe and effective vaccine to prevent Covid-19 by the end of the year or early 2021.
Last month, the company started a phase three trial testing how safe and effective it is on 30,000 people with results expected as early as October. The company said it anticipates completing enrollment for its phase three trial in September.
Moderna is charging between $32 and $37 per dose for its coronavirus vaccine for some customers, under cheaper “pandemic pricing,” it said earlier this month. At the time, the company said it was in discussion for larger volume agreements that will have a lower price.
Earlier this month, President Donald Trump announced the U.S. government would purchase 100 million doses of Moderna’s vaccine in a deal worth $1.53 billion. The U.S. has already invested $955 million in Moderna’s vaccine development, bringing its total investment up to nearly $2.5 billion.
While there is hope scientists will find a safe and effective vaccine, there is never a guarantee, scientists say. They warn that questions remain about how the human body responds once it’s been infected with the virus.
One question among scientists is whether antibodies produced in response to Covid-19 offer protection against getting infected again.
Scientists expect that antibodies provide some degree of protection against getting Covid-19, but they can’t say that definitively yet since the coronavirus was first discovered less than eight months ago. Hong Kong researchers on Monday reported what appears to be the first confirmed case of Covid-19 reinfection, a man who was first infected by the virus in late March and then, 4½ months later, seemingly contracted the virus again.