Moderna announced Tuesday that its coronavirus vaccine is 90 percent effective against all forms of COVID-19, reflecting a slight decrease from the previous 94.1 percent effectiveness rate, which was published in the New England Journal of Medicine in December.

These new results come from the third phase of continuous clinical trials of the vaccine with the participation of more than 30,000 volunteers across the United States.

The press release of the leading biotechnology company did not indicate the reason for the decreased effectiveness, but this may be due to the emergence of new mutations.

Moderna is working on two types of enhancers for the mutated versions of the virus, and the company said that the experiments conducted on mice showed that they triggered an increased immune response. The results of this study have been published on scientific sites, and are awaiting scientists' reviews.

"The new pre-clinical data for our candidate vaccine for mutants gives us confidence that we can proactively address emerging mutants," said CEO Stephane Bancel.

As of April 12, the company said it had delivered 132 million doses of its vaccine worldwide, including about 117 million doses, to the United States.

The company is still on track to deliver 100 million doses by the end of May and another 100 million doses in July.