Aug 9 (Reuters) - Shares of U.S. vaccine maker Novavax fell about 30% on Tuesday after it cut its annual revenue forecast by half over falling demand for its COVID-19 shot from low- and middle-income nations.

Demand for its vaccine is also waning in the United States, where it was authorized for use among adults last month and was expected to be preferred by the skeptics of messenger RNA-based shots from Moderna Inc and Pfizer Inc.

But only 7,381 Novavax vaccine doses have been administered so far in the country and Chief Executive Stanley Erck said that its late launch could have hampered demand.

The company now expects 2022 revenue between $2 billion and $2.3 billion, compared with its prior forecast of $4 billion to $5 billion when it was hoping to benefit from the demand for its shots as part of the COVAX vaccine sharing program.

Novavax shares fell 29.6% to close down at $40.28 a share.

"Timing continues to be our enemy," Novavax Chief Business Officer John Trizzino said in an interview.

He said the company does not expect to pick up significant market share of booster shots this fall as other vaccine makers roll out new shots designed to target newer COVID-19 variants.

Still, he said that developing its own updated version of the vaccine will help as the company gears up to compete next year.

"All of the obstacles that have been in our way in 2022 will not be there in '23," he said.

Analysts still expect the company to capture a small but meaningful share of a fast-developing market for COVID-19 re-vaccinations.

It could still be a viable COVID vaccine player in the future $5-10 billion market as it has shown a comparable or better clinical profile versus mRNA vaccines, Jefferies analyst Roger Song said in a note. (Reporting by Mrinalika Roy in Bengaluru and Michael Erman in New Jersey; Editing by Arun Koyyur and Deepa Babington)