What happened Shares of VBI Vaccines (NASDAQ: VBIV) were vaulting 5.9% higher as of 11:19 a.m. EST on Friday after rising as much as 20.5% earlier in the day. The nice gain came after the company announced positive results from a phase 4 study of its three-antigen hepatitis B virus (HBV) vaccine Sci-B-Vac in younger adults. So what VBI said that Sci-B-Vac achieved a seroprotection rate of at least 95% in adults between the ages of 20 and 40 within two months after the second dose of the vaccine. This reflected relatively quick protection against HBV infection in younger adults. Image source: Getty Images. Sci-B-Vac has already been approved and launched commercially in Israel. The phase 4 study was conducted in support of establishing the batch included in the study as a new reference standard. Before vaccines are made available in Israel, they must first be tested against a reference vaccine batch that has been evaluated in a clinical study. Investors' enthusiastic reaction to VBI's news, though, probably didn't relate much to the prospects for Sci-B-Vac in Israel. The company hopes to win regulatory approvals for the vaccine in the U.S., Canada, and Europe. The positive phase 4 results no doubt increased investors' optimism that VBI will be successful in expanding the markets for Sci-B-Vac. Now what The European Medicines Agency (EMA) accepted VBI's filing for approval of its HBV vaccine in December. VBI also submitted a Biologics Licensing Application (BLA) to the U.S. Food and Drug Administration (FDA) last month. The next big catalyst for the biotech stock could come later this year if Sci-B-Vac gets a thumbs-up from the FDA and/or the EMA. 10 stocks we like better than VBI VaccinesWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and VBI Vaccines wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of November 20, 2020 Keith Speights has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source