No. Authors still retain ownership and control of the copyright in their research products, subject only to the prior, non-exclusive rights granted to the NIH under the NIH Public Access Policy.
As a prior license, this Government Use License cannot be overridden by any subsequent agreements into which an author may enter, including publishing agreements requiring transfer of exclusive rights from the author to the publisher. Hence, the Government Use License makes compliance with the Policy more efficient and ensures the NIH may make research findings publicly available.