CVS (CVS - Get Report) investors and analysts applauded after the pharmacy easily beat earnings estimates for its first quarter of 2019 and raised full year guidance, but there's still considerable room for skepticism. 

The stock is up 3.7% to $56.13 a share since reporting earnings before the open on May 1, and several sell-side analysts raised their revenue and earnings estimates on the stock. 

Earnings per share came in at $1.62 per share, beating Wall Street expectations of $1.51. Group revenues were $61.6 billion, beating analysts estimates of $60.39 billion. The company also raised its 2019 adjusted operating income guidance to a range between $15 billion to $15.2 billion and confirmed its free-cash-flow guidance of $9.8 billion to $10.3 billion. 

The stock is down roughly 14% this year, and as Credit Suisse put it in a downgrade note before the earnings, CVS is "facing a transitional year as it tries to drive seismic changes in health care." 

CVS isn't yet out of the woods, some analysts argue. 

"We maintain our Market Perform rating as we think it's too early to have confidence that CVS has yet turned a corner on fundamentals," said BMO Capital Markets analyst Matt Borsch in a note out Thursday evening, in which he raised his price target to $63, representing about 12% upside. He raised his EPS estimates for 2019, 2020 and 2021 to  $6.84, $7.03 and $7.85, respectively. 

"We still see substantial risk for a deterioration in results as we move through this year (with related execution risk given the number of complex tasks at hand)," Borsch said. He's still cautious on the integration of Aetna, CVS's Omnicare long-term care unit and the retail segment, the last of which is seeing operating margins pressured by customer reimbursements. 

Goldman Sachs analyst Robert Jones raised his EPS estimates through 2021, but said "We look for further clarity on the company's growth trajectory, and whether the new cost savings program and growth initiatives will be enough to offset challenging core trends. We remain neutral rated."'

CVS is a holding in Jim Cramer's Action Alerts PLUS member club . Want to be alerted before Jim Cramer buys or sells CVS? Learn more now.