An early clinical trial conducted with Moderna’s (MRNA) potential COVID-19 vaccine has shown promise in elderly patients, the company announced in a presentation on Wednesday.

The clinical trial tested the proposed COVID-19 vaccine on 10 adults ages 56 to 70 and 10 adults ages 71 and older, with each participant receiving two 100 microgram doses of the vaccine. The doses were administered 28 days apart for each patient.

Moderna said the participants in the trial showed the ability to produce neutralizing antibodies, believed necessary to build up an immunity to the virus. The vaccine also demonstrated good tolerability with no serious adverse side effects reported, the biotech firm said.

Symptoms of the vaccine inoculation included fatigue, chills, headaches, and pain at the injection site, which Moderna said subsided within two days for most patients.

Moderna has entered into a $1.53 billion agreement with the U.S. government for 100 million doses of its vaccine if approved. Moderna said it will charge between $32 and $37 per dose of its COVID-19 vaccine for some customers as part of its cheaper “pandemic pricing,” CNBC reported.

Moderna, along with several other drug makers, is developing a vaccine to treat the virus, which has been confirmed in more than 23.9 million people globally, with deaths from COVID-19 topping 820,000 reported, according to Johns Hopkins University.

Moderna’s clinical trial results came just ahead of VBI Vaccines (VBIV) announced data from three preclinical mouse studies, which has allowed the biopharmaceutical company to select two vaccine candidates to take into Phase 1/2 human clinical trials.

The trials are expected to begin around the end of 2020 and are subject to regulatory approval.

“We are excited to announce these impressive pre-clinical data, which we believe clearly support the advancement of the two vaccine candidates, VBI-2901 and VBI-2902, into human clinical studies around the end of the year,” Jeff Baxter, VBI’s president and CEO, said in a statement. “An effective solution to the ongoing COVID-19 pandemic will require a vaccine that is capable of providing robust protection, quickly."

Baxter said the data indicate the VBI-2900 program has the potential to be administered as a one-dose vaccine regimen.

Shares of Moderna were trading at $70.00 as of 12:46 p.m. EDT, up $3.75 or 5.66%. VBI was off nearly 3.2% or 7.5 cents at $3.20 a share.

A US biotech firm Moderna has reported 'positive interim' results in early testing of a vaccine candidate A US biotech firm Moderna has reported 'positive interim' results in early testing of a vaccine candidate Photo: AFP / Thibault Savary