June 13 (Reuters) - The U.S. Department of Health and Human Services (HHS) said on Thursday it will provide up to $500 million for mid-stage trials evaluating vaccines administered as a nasal spray or pill to protect against symptomatic COVID-19.

The funding is part of Project NextGen, a $5 billion initiative led by the Biomedical Advanced Research and Development Authority (BARDA), to advance a pipeline of new, innovative vaccines and therapeutics providing broader and more durable protection against COVID-19 infection.

BARDA, which helps companies develop medical supplies to address public health threats, is a part of HHS.

The project is awarding up to $453 million to Vaxart for a study that will evaluate its oral COVID vaccine. The company's shares more than doubled to $1.78 after market.

It is also awarding privately held Castlevax and Cyanvac around $34 million and $40 million, respectively, to develop their intranasal vaccine candidates.

Each trial will enroll 10,000 volunteers and compare the efficacy and safety of the investigational vaccines to FDA-licensed vaccines.

"Currently approved COVID-19 vaccines are administered intramuscularly and, while extremely effective, are limited in their capacity to induce a robust immune response in mucosal areas such as the mouth, nose and gut, where the SARS-CoV-2 virus first enters the body," the HHS said. (Reporting by Puyaan Singh in Bengaluru; Editing by Shounak Dasgupta)