Novavax’s protein-based jab utilizes a decades-old technology that is common in flu and hepatitis vaccinations, making it an appealing alternative to people who want to be inoculated against COVID-19 but are wary of relatively nascent mRNA vaccines.

Despite the good news out of Japan, Novavax’s Nasdaq-listed shares continued a monthslong slide on Monday, when Japan’s Ministry of Health first announced it planned to approve the vaccine, dropping 7%. Novavax’s share price has plummeted 62% to $55.16 from $142.90 at the start of the year.

Some Novavax investors feel like the vaccine is arriving too late to the party, as vaccination rollouts have already matured in many major markets. Novavax is still awaiting approval in the U.S., after filing an application with the Food and Drug Administration (FDA) in late January, but has been accepted in countries including Australia, India, Canada, and much of the EU.

Japan’s Chief Cabinet Secretary Hirokazu Matsuno said at a regular news conference on Tuesday that Novavax’s Covovax jab will provide the country with “some diversity in vaccines.” Roughly 80% of Japan’s population is fully vaccinated with two doses, and most have received mRNA COVID vaccines developed by BioNTech or Moderna.

AstraZeneca’s viral vector vaccine is available in Japan, too, but most of the country’s supply of AstraZeneca shots, which are manufactured domestically, have been donated to other countries.

Tokyo has agreed to purchase 150 million doses of the Novavax vaccine over the course of this year, with an initial 100,000 doses expected to be delivered to local governments beginning in late May.