NEW YORK (TheStreet) -- Shares of Novavax(NVAX) - Get Report were plunging 84.17% to $1.32 in after-hours trading on Thursday after the company said its RSV-F vaccine candidate for lower respiratory tract disease did not meet its primary and secondary goals in a clinical trial.

The vaccine was well-tolerated by patients. But it did not demonstrate efficacy in preventing RSV-associated lower respiratory tract disease or reducing the occurrence of all symptomatic respiratory disease, according to a company statement.

Novavax was "surprised and disappointed" by the outcome, according to Gregory Glenn, president of research and development.

"Our initial analyses and review of the key aspects of the trial do not indicate issues with trial execution, data collection, data integrity, or drug product quality," he added.

The Gaithersburg, MD-based vaccine company will take a closer look at data in the upcoming weeks to better understand the results.

More than 15.57 million of the company's shares traded hands today vs. the 30-day average volume of 5.3 million shares.

Separately, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

TheStreet Ratings rated this stock as a "sell" with a ratings score of D.

The company's weaknesses can be seen in multiple areas, such as its feeble growth in its earnings per share, deteriorating net income, disappointing return on equity, weak operating cash flow and generally high debt management risk.

You can view the full analysis from the report here: NVAX

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