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Merck drops 2 potential COVID-19 vaccines after poor results in early testing

Doctor on vaccine's efficacy against variants
Doctor on vaccine's efficacy against variants... 08:08

Merck is pulling the plugs on two potential COVID-19 vaccines following poor results in early-stage studies. The drugmaker said Monday it will focus instead on studying two possible treatments for the virus that also have yet to be approved by regulators. 

Merck said its potential vaccines were well tolerated by patients, but they generated an inferior immune system response compared with other competitors' new vaccines. The company is focusing its efforts instead on advancing clinical programs and manufacturing for two potential treatment medications for the virus: MK-7110 and MK-4482 (also known as molnupiravir. Molnupiravir is being developed in collaboration with Ridgeback Bio.

 "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," Dr. Dean Y. Li, president of Merck Research Laboratories, said in a release.

Merck entered the race to fight COVID-19 later than other top drugmakers. It said last fall that it had started early-stage research in volunteers on potential vaccines that require only one dose. Vaccines developed by Pfizer and Moderna were already in late-stage research at that point.

Shares in the company fell 1% following the announcement Monday morning. 

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The Food and Drug Administration allowed emergency use of both the Pfizer and Moderna vaccines late last year. Each requires two shots.

Since vaccinations began in December, nearly 22 million doses have been delivered to people nationwide, according to the Centers for Disease Control and Prevention. A total of 3.2 million people in the U.S. have received both doses required for those vaccines.

Operation Warp Speed

The government is paying Merck about $356 million to fast-track production of one of its potential treatments under Operation Warp Speed, a push to develop COVID-19 vaccines and treatments. 

The money will allow the Kenilworth, New Jersey, company to deliver up to 100,000 doses by June 30, if the FDA clears the treatment for emergency use.

The treatment, known as MK-7110, has the potential to minimize the damaging effects of an overactive immune response to COVID-19, which can complicate the life-saving efforts of doctors and nurses. Phase-3 study data, according to a company press release, showed the risk of death or respiratory failure in hospitalized COVID-19 patients treated with a single dose of MK-7110 was reduced by more than 50%.

Meanwhile, molnupiravir, the company's other treatment which is still in clinical trials, is an oral drug that has the potential to stop community spread of the virus by suppressing the virus in the carrier. 

"This drug may actually be able to rapidly block transmission from an infected animal or patient to an uninfected contact or person," Dr. Richard Plemper, who leads a research team of eight scientists at Georgia State University who've been studying the drug, told CBS affiliate WGCL-TV's Hayley Mason. If approved by the FDA, the drug could be a "game-changer" Plemper said.

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