Merck & Co. is ending development of its two experimental Covid-19 vaccines, after early data showed they could not produce immune responses to the virus, the company announced Monday.

Why it matters: The news leaves one of the top pharmaceutical companies out of the running for producing a vaccine, as demand for the inoculation is outstripping supply.

• Vaccines by its competitors, Pfizer and Moderna, have already received emergency authorization in the U.S.

What's next: Merck said it will continue to advance clinical programs for two treatments in the late stages of development.

What they're saying: “We are grateful to our collaborators who worked with us on these vaccine candidates and to the volunteers in the trials,” said Dr. Dean Y. Li, president of Merck Research Laboratories.

• “We are resolute in our commitment to contribute to the global effort to relieve the burden of this pandemic on patients, health care systems and communities.”