LONDON — AstraZeneca said Thursday it's working with the University of Oxford to adapt its COVID-19 vaccine to protect against new strains of the virus as public health officials raise concerns about mutations that may make the virus more resistant to existing vaccines.

The Anglo-Swedish drugmaker worked with Oxford to develop one of the first COVID-19 vaccines authorized for widespread use. AstraZeneca said it hopes to cut the time needed to produce large amounts of any new vaccine to between six and nine months.

The comments came as Astra-Zeneca said fourth-quarter net income rose to $1.01 billion from $313 million in the same quarter a year earlier. Drug sales increased 11% to $7.41 billion, driven by a 24% increase in cancer treatments.

The company posted $2 million of revenue from its COVID-19 vaccine, which it has pledged to supply on a non-profit basis during the pandemic, and said it would begin reporting sales of the vaccine separately beginning in the next quarter.