Larry Merlo, president and chief executive officer of CVS Health Corp., speaks during an interview in New York, May 9, 2019.

CVS Health tried to allay investor concerns Tuesday over its $70 billion acquisition of health insurer Aetna last year, projecting double-digit growth after the two companies are fully integrated in a few years.

The company reiterated its 2019 forecast of earnings between $6.75 and $6.90 per share, compared with the $6.85 analysts polled by Refinitiv are expecting. For 2020, CVS expects adjusted earnings of "at least" $7, it told investors at its annual investor day in New York. Analysts anticipate $7.22 a share.

For 2021, CVS "mid-single digit percent" adjusted earnings. In 2022 and the following years, CVS expects "low-double digit percent" growth. Shares of the company rose 3.6% in morning trading.

Investors have pressed for more clarity around the company's long-term financial prospects, especially after executives warned of headwinds earlier this year. J.P. Morgan analysts surveyed investors ahead of analyst day and found long-term financial guidance was the the most important thing respondents said they wanted to learn Tuesday.

"Keep in mind we're in the early innings of our transformational journey," CVS CEO Larry Merlo told investors. "This will be a multi-year journey with benefits building over time as we continue to build and refine new programs to better serve the needs of our stakeholders."

CVS acquired health insurer Aetna, an expensive bet that combining insurance, prescription drug benefits and CVS' 10,000 drugstores would help the combined company compete in the changing health-care industry. Investors appear skeptical so far, with the company's stock price sliding 20% this year.

The company on Tuesday said it expects the deal to result in $300 million to $350 million in synergies this year, and $800 million next year, up from the previously forecast $750 million.

Evercore analysts Ross Muken and Michael Newshel in a note to clients said "the 2020 color is a net positive as it sets a floor (which is key!) for allowing investors to gain confidence in the earnings stream."

"In addition, investors are likely to scrutinize the components of the outlook, but it matches our view (though consensus may come down a touch)," they said.

CVS also announced it will open 1,500 HealthHUB stores by the end of 2021. These remodeled drugstores focus more on health services and products and less on candy and greeting cards.