(Reuters) – Data from a small, early-stage safety trial testing Moderna Inc’s <MRNA.O> experimental COVID-19 vaccine does not provide the critical data needed to assess its effectiveness, health-focused Stat News reported on Tuesday, citing experts.

The news publication’s report https://bit.ly/36kKerh pulled down shares of the Cambridge, Massachusetts-based biotech and erased modest gains on the benchmark S&P 500 index <.SPX>.

Moderna said on Monday the vaccine candidate, the first to be tested in the United States, produced protective antibodies in a small group of healthy volunteers.

The news, while based on initial data from just eight people and not intended to assess the vaccine’s efficacy, nevertheless sent Moderna shares up 20% on Monday, and also pushed the broader markets higher.

Moderna later announced a stock sale that could raise about $1.5 billion, sending shares lower early on Tuesday.

Stat quoted health experts saying that Moderna had not provided enough data in its news release to judge the vaccine candidate.

Issues noted by Stat included:

– a lack of data about the responses to the medicine from other participants in the 45-subject study

– lack of information about the ages of the eight subjects whose antibodies were analyzed, an important question given the virus is particularly lethal to older people

– lack of comment from Moderna’s U.S. government partner on the vaccine, the National Institute for Allergy and Infectious Diseases

– the data is based on early responses to the vaccine, leaving unclear how long any immunity produced by the vaccine might last.

Moderna did not immediately respond to a Reuters’ request for comment.

The company’s shares closed down 10.4% at $71.67.

(Reporting by Manojna Maddipatla in Bengaluru; Editing by Sriraj Kalluvila and Bill Berkrot)

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