NEW YORK - US states have wasted an average of 4.8 percent of their available doses of COVID-19 vaccines, the California Department of Public Health told The San Francisco Chronicle last week, citing the figures from the US Centers for Disease Control and Prevention (CDC).

The main reasons for discarding the COVID-19 vaccines are that the drug has expired, has been opened and will go bad before it can be used, or has been misused and ruined, the Chronicle quoted experts as saying.

At the same time, the percentage of doses that must be thrown away each month statewide, though still a small amount, has risen steadily since last spring, it added.

In California, health professionals have thrown out nearly 645,000 doses of life-saving COVID-19 vaccines since they became available in December, averaging 58,614 per month, according to the California Department of Public Health.

The daunting figure nevertheless represents just 1 percent of the total 58 million doses made available in California between Dec. 15 and Oct. 22, it added.

The CDC didn't respond to the reports. However, last month, NBC News quoted the federal agency as saying that vaccine suppliers threw out more than 15 million doses between March and August.