 Companies at the forefront of coronavirus vaccine research have been a veritable gold mine for investors this year. For example, shares of Moderna NASDAQ: MRNA have gained a staggering 278 over the first seven months of 2020, while Novavaxs NASDAQ: NVAX stock has posted a healthy 3,500 return on investment during this same period. While Heat Biologics NASDAQ: HTBX and Vaxart NASDAQ: VXRT have both made quantum leaps in terms of their market caps this year, theres a strong chance that each of these lesser-known COVID-19 vaccine stocks may soon be gearing up for another jaw-dropping move higher. 