Merck is canceling development of two potential COVID-19 vaccines due to poor initial results

Merck will stop developing two possible COVID-19 vaccines after poor results in the initial studies.

The drugmaker said Monday it will instead focus on studying two potential treatments for the virus that have not yet been approved by regulators. The company said its potential vaccines were well tolerated by patients, but elicited a lower immune system response compared to other vaccines.

Merck developed one of the possible vaccines with the Pasteur Institute in France based on an existing measles vaccine. The French institute said it will continue to work on two more vaccine projects using different methods.

Merck entered the race to combat COVID-19 later than other major drug companies.

He said last fall that he had started early research in volunteers for possible vaccines that require only one dose. The vaccines developed by Pfizer and Moderna were already at an advanced stage of research at that time.

The Food and Drug Administration approved emergency use of the Pfizer and Moderna vaccines late last year. Each requires two doses.

Five potential vaccines have reached advanced testing in the United States, the final stage before a drug manufacturer seeks regulatory approval. Results from a single dose candidate developed by Johnson & Johnson are expected shortly.

Since the start of vaccines in December, nearly 22 million doses have been delivered to people across the country, according to the Centers for Disease Control and Prevention. Almost 6% of the population has received at least one dose.

In total, 3.2 million people, or 1% of the population, have received the two doses required for these vaccines.