"We expect to continue to see more cases of swine flu, more serious cases and, unfortunately, more deaths," said Ken August, spokesman for the California Department of Public Health.

Though health officials expected the spread of swine flu to slow in the hot summer months, as influenza viruses often do, the virus hasn't gone away, August said.

"While the majority of cases have been mild so far, public health officials remain very concerned that the virus could evolve into a more serious strain of influenza," he said.