(VICL) To Present Preclinical Data for Congenital CMV DNA Vaccine at International Conference

• A Vaxfectin^®-formulated gB DNA vaccine induces antibodies that block cytomegalovirus entry into fibroblasts and epithelial cells in preclinical study
• Data presented at the 5^th International Congenital CMV Conference in Brisbane, Australia

SAN DIEGO, April 21, 2015  — Vical Incorporated (Nasdaq:VICL) today announced that Michael McVoy, Ph.D., Professor of Pediatrics at Virginia Commonwealth University, presented data from preclinical studies testing several combinations of Vaxfectin^®– formulated glycoprotein-B (gB)-encoding DNA vaccines for neutralizing antibody responses. The data were featured at the 5^th International Congenital CMV Conference held April 20-24, 2015, in Brisbane, Australia. Vaxfectin is Vical’s novel, proprietary cationic lipid-based adjuvant and is used in CyMVectin^™, the company’s congenital CMV vaccine candidate. The studies found that vaccines encoding gB provided both fibroblast and epithelial entry neutralizing titers that were comparable to those observed in sera from humans with naturally-acquired CMV infections. The data suggest that CyMVectin has the potential to induce neutralizing antibodies against a broad range of cells.

“A vaccine to prevent birth defects caused by cytomegalovirus is a public health priority,” said Dr. Stuart Adler, M.D., Emeritus Professor, Department of Microbiology and Immunology, at Virginia Commonwealth University. “Accumulating evidence suggests that induction of antibodies that block viral entry into a broad range of cell types is an important determinant of vaccine efficacy. A gB DNA vaccine performs well in this regard, when compared with responses induced by natural infection. In addition, the simplicity of a single subunit delivered by DNA immunization is highly attractive compared with more complicated vaccines in development.”

“We believe that induction of both fibroblast and epithelial entry neutralizing antibodies is essential for providing protection against CMV,” said Larry Smith, PhD., Vical’s Vice President of Vaccine Research. “These findings support further development of CyMVectin for prevention of congenital CMV infections.”

About Congenital CMV

Currently, in the United States, approximately 40,000 children are born with a congenital CMV infection each year. Of these, about 4,000 have symptoms at birth and will have severe sequelae including deafness, mental impairment, and/or death. According to the National Cytomegalovirus Registry for Pregnant Women, congenital infection of a fetus usually occurs when a woman’s first CMV infection occurs during pregnancy. In the United States approximately 60% of pregnant women are seronegative and between 1% and 2% will have a primary CMV infection during pregnancy. The rate of CMV transmission to the fetus after a primary maternal infection during pregnancy is between 25% and 75% depending on gestational time of infection.

About Vical

Vical develops biopharmaceutical products for the prevention and treatment of chronic or life-threatening infectious diseases, based on its patented DNA delivery technologies and other therapeutic approaches. Additional information on Vical is available at www.vical.com.

Forward-Looking Statements

This press release contains forward-looking statements subject to risks and uncertainties that could cause actual results to differ materially from those projected. Forward-looking statements include the potential benefits of CyMVectin and potential future development of CyMVectin. Risks and uncertainties include whether Vical or others will continue development of CyMVectin, whether planned clinical development of CyMVectin will begin when expected, or at all, whether the results of future preclinical or clinical studies will be consistent with prior preclinical studies or will otherwise merit further development; whether Vical will seek or gain approval to market any product candidates, including CyMVectin; and additional risks set forth in the company’s filings with the Securities and Exchange Commission. These forward-looking statements represent the company’s judgment as of the date of this release. The company disclaims, however, any intent or obligation to update these forward-looking statements.

CONTACT: Andrew Hopkins
         (858) 646-1127
         Website: www.vical.com