Jan 20 (Reuters) - Amazon.com Inc on Wednesday offered to help with the United States' efforts involving the COVID-19 vaccine, according to a letter addressed to President Joe Biden, seen by Reuters.

The world's largest online retailer has an agreement with a healthcare provider to administer vaccines at its facilities and will move forward once doses are available, Dave Clark, chief executive of Amazon's worldwide consumer business, said in the letter.

Beyond offering the vaccine to Amazon employees, Clark added, "We are prepared to leverage our operations, information technology, and communications capabilities and expertise to assist your administration's vaccination efforts."

The offer comes as Biden became the 46th U.S. president of on Wednesday. The president has laid out a goal of delivering 100 million COVID-19 vaccine doses within his first 100 days in office, an endeavor Amazon aims to support. Clark congratulated Biden and Vice President Kamala Harris on their inauguration.

The company employs more than 800,000 people in the United States, making it the second-biggest private employer behind Walmart Inc. More than 19,000 U.S. workers at Amazon had contracted the virus as of September, underscoring the vaccine's importance to keeping its staff safe and warehouses operational.

Amazon said in the letter that its scale would let it make an impact in countering the virus, but it did not provide details on the form its help could take. The company did not immediately answer a request for comment on its vaccine rollout if any so far. (Reporting By Jeffrey Dastin in San Francisco; Editing by Nick Zieminski)