Moderna's closely watched early-stage human trial for a coronavirus vaccine produced Covid-19 antibodies in all 45 participants, the biotech company announced Monday, sending the company's shares surging nearly 20%.
Each participant received a 25, 100 or 250 microgram dose, with 15 people in each dose group. Participants received two doses of the potential vaccine via intramuscular injection in the upper arm approximately 28 days apart.
At day 43, or two weeks following the second dose, levels of binding antibodies in the 25 microgram group were at the levels generally seen in blood samples from people who recovered from the disease, the Cambridge, Massachusetts-based company said. Those in the 100 microgram had antibodies that "significantly exceeded levels" in recovered patients. Data on a second dose was not available for the 250 microgram group, the company said.
The vaccine also produced neutralizing antibodies against Covid-19 in at least eight participants, the company said. Experts have said neutralizing antibodies appear to be important in acquiring protection.
Four participants were assigned to receive a 25 microgram dose, while the other four received 100 micrograms. Levels of neutralizing antibodies were at or above levels seen in blood samples, the company said. Data on neutralizing antibodies for the other participants were not yet available, Moderna said.
"These interim Phase 1 data, while early, demonstrate that vaccination with mRNA-1273 elicits an immune response of the magnitude caused by natural infection starting with a dose as low as 25 [micrograms]," Moderna chief medical officer Dr. Tal Zaks said in a statement.
"When combined with the success in preventing viral replication in the lungs of a pre-clinical challenge model at a dose that elicited similar levels of neutralizing antibodies, these data substantiate our belief that mRNA-1273 has the potential to prevent COVID-19 disease and advance our ability to select a dose for pivotal trials," Zaks added.
Scientists hope the antibodies provide some degree of protection against getting Covid-19, but they can't say that definitively yet since it hasn't been studied and some patients appear to have been reinfected after recovering from the virus.
There are no formally approved treatments for Covid-19, which has killed at least 315,225 and sickened 4.7 million people worldwide since emerging from the Chinese city of Wuhan more than four months ago, according to Johns Hopkins University. U.S. officials have said producing a vaccine to prevent Covid-19 would take 12 to 18 months at the earliest.
More than 100 vaccines are under development globally, according to the World Health Organization. At least eight vaccines are in human trials.
Moderna, which has been fast-tracking work with the National Institutes of Health to develop a vaccine, is the first company to release data on a human trial testing a coronavirus vaccine.
The company said it expects to begin a phase 3 trial in July.
Earlier this month, Moderna announced that it was wrapping up phase one human trials on its potential vaccine with the U.S. government and is moving to start phase two trials that would include 600 participants. If the vaccine is found to be effective and safe to use, it could be ready for the market in early 2021, the company said.
The company said the vaccine was generally safe and well tolerated. To date, the most notable adverse events were seen in the 250-dose group where three participants developed "grade 3 systemic symptoms," following the second dose, the company said.
The potential vaccine by Moderna contains genetic material called messenger RNA, or mRNA, that was produced in a lab. The mRNA is a genetic code that tells cells what to build — in this case, an antigen that may induce an immune response to the virus.
The phase 1 trial took place at the Kaiser Permanente Washington Health Research Institute in Seattle. It tested the vaccine on 45 males and nonpregnant females ages 18 to 55.
— CNBC's Meg Tirrell contributed to this report.