The job of an investor is to buy top-notch companies in essential economic sectors at reasonable valuations and hold them over the long term.

Because everyone will need access to healthcare services in their life, healthcare is an especially important sector of the economy. In that spirit, here are two healthcare giants with promising fundamentals and valuations that could lead to significant capital appreciation both in and well past 2023.

1. Sanofi: A world-class medicines and vaccines company

Sanofi (SNY 5.56%) is likely best known for its smash-hit immunology drug co-owned with Regeneron (REGN -2.94%) called Dupixent. The company's share of sales from the drug through the first three quarters of 2022 topped $6 billion, which was up 44.5% over the year-ago period. Considering that Dupixent was recently approved for more indications like eosinophilic esophagitis, sales should continue to move higher.

And with five other medicines and two vaccine franchises poised to surpass $1 billion in 2022 sales, the company is much more than its major immunology drug. In fact, Dupixent only accounted for just 18.3% of the company's year-to-date sales.

What makes Sanofi such a quality pharmaceutical company is that it doesn't get too comfortable with its success: The drugmaker boasts a pipeline of 80-plus projects in different stages of clinical development. As a result, analysts expect Sanofi's earnings to grow at 12.3% annually over the next five years as more drugs are brought to market. For context, this is far higher than the 6.9% drug manufacturer industry average growth forecast.

Given that Sanofi's 3.6% dividend yield is twice the S&P 500 index's 1.7% yield, income investors may also like the stock. This is especially true with the forward dividend payout ratio expected to be just 35.8%, which means the dividend is quite sustainable.

Finally, value investors will love the fact that Sanofi's forward price-to-earnings (P/E) ratio is just 11.1. This is significantly cheaper compared to the overall drug manufacturer industry average forward P/E ratio of 15. With such a low valuation, it isn't surprising that the average 12-month analyst price target of $64 represents a staggering 30% upside from the current $49 share price.

2. Elevance Health: A leader in the massive health insurance market

With its Anthem Blue Cross and Blue Shield health plan brand, Wellpoint Medicaid brand, and Carelon healthcare services brand, Elevance Health (ELV 0.65%) serves over 119 million people. The company's $111 billion market capitalization positions it as the third-biggest publicly traded health insurer in the world, narrowly behind CVS Health's (NYSE: CVS) $115 billion market cap.

Health insurance is poised to grow in importance with each passing year. This is because as chronic diseases become more prevalent and the burden on the healthcare system rises, the demand for health insurance will increase as well. That's why the global health insurance market is predicted to compound at 4.4% annually from $2.6 trillion in 2021 to $3.3 trillion by 2028.

Given the $155.9 billion in revenue that analysts expect from Elevance Health in 2022, the company's share of the global health insurance market is approximately 6%. As the health insurer executes acquisitions and experiences organic growth, earnings are expected to climb 11.9% each year through the next five years. This is basically in line with the healthcare plan industry average growth projection of 12.5%.

At first glance, Elevance Health's 1.1% dividend yield isn't going to wow income investors. But with the dividend payout ratio set to come in below 18% in 2022, strong dividend growth prospects make up for the lower starting income.

Elevance Health's forward P/E ratio of 14.4 is just below the healthcare plans industry average forward P/E ratio of 14.6. This is a sensible valuation for a wonderful business, which is why analysts have an average 12-month share price target of $579. That equates to capital appreciation of 21% over the current $479 share price.