Health insurer Cigna Corp reported quarterly profit below estimates on Thursday, as COVID-19 testing and treatment costs piled up due to a surge in infections across the country.

While health insurers largely benefited from a slump in patient use of discretionary healthcare services last year during the peak of the COVID-19 pandemic, costs related to their programs to support customers with COVID-19 testing and treatment have largely offset the gains.

For the fourth quarter, Cigna's medical care ratio - the amount spent on medical claims versus the income from premiums - worsened to 85.8% from 82.3%, owing to COVID-19 testing and treatment costs.

Larger rival UnitedHealth last month said it expected COVID-19-related cost trends in 2021 to remain similar to 2020, despite the ongoing vaccination efforts.

Cigna said it expects to see a negative impact of about $1.25 per share due to COVID-19 costs in 2021.

The company said it sees full-year consolidated adjusted income from operations of at least $6.95 billion, or $20 per share.

Adjusted revenue from Cigna's health services business, which includes the pharmacy benefits management unit Cigna added through its buyout of Express Scripts, rose about 19% to $30.53 billion in the reported quarter from $25.57 billion a year earlier.

The company recorded $3.22 billion in gains from the sale of its disability and accidental death insurance unit in December.

Excluding one-time items, the company posted a profit of $3.51 per share, below Refinitiv IBES estimates of $3.68 per share.

Adjusted revenue rose to $41.67 billion, beating consensus estimate of $39.99 billion.