For income investors, building a diversified portfolio of dividend stocks should be a top priority. That's because owning a wide array of stocks that span numerous industries reduces your risk profile. A payout cut for a stock that produces 1% of your total dividend income is far less painful than a cut for a stock that accounts for 10% of it.

If your portfolio needs more exposure to the healthcare industry, here are three high-quality biotech dividend stocks that you should think about buying in November.

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1. AbbVie

AbbVie (NYSE:ABBV) manufactures the top-selling prescription drug in the world: Humira, an immunosuppressive used to treat a number of conditions. The stock's dividend yield at current share prices is 4.8% -- several times higher than the S&P 500's 1.3% yield. And while that may lead investors to worry that AbbVie is a yield trap, shareholders should actually be able to sleep well at night.

First, the biopharmaceutical giant just raised its quarterly dividend by 8.5% at the end of October -- a telling sign that management has confidence in the company's future. Based on AbbVie's drug portfolio and year-to-date operating results, this optimistic outlook appears to be justified.

For instance, for the first three quarters of 2021, AbbVie's net revenue grew 29.2% year over year to $41.2 billion. Its neuroscience segment has contributed to 23.3% of year-to-date sales growth, which was driven by a rebound in Botox sales as elective procedures picked up again after 2020's pandemic-related declines, and increased sales for the anti-psychotic drug Vraylar. 

Humira will lose patent protection in the U.S. in 2023, but AbbVie's next-generation drugs Skyrizi and Rinvoq have contributed 71% of AbbVie's immunology segment revenue growth year to date. Meanwhile, Humira chipped in the other 29%. Indeed, Skyrizi and Rinvoq more than doubled their combined revenue to $3.2 billion -- a signal that those two drugs will be able to promptly return AbbVie to growth in 2024 after what is expected to be a revenue slide in 2023. Skyrizi and Rinvoq appear capable of replacing most of the expected revenue losses from Humira, while other drugs like Vraylar can add meaningful revenue growth in their own right.

AbbVie's dividend payout ratio will be in the low-40% range for this year, which should leave it plenty of cushion to absorb a temporary revenue decline in 2023 without cutting the payout. And AbbVie is currently trading at a bargain-bin valuation of barely 9 times this year's anticipated non-GAAP earnings. 

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2. AstraZeneca

AstraZeneca (NASDAQ:AZN) offers investors a market-beating 2.2% dividend yield, and that payout looks to be safe for the foreseeable future.

First, its dividend payout ratio should also land in the low-40% range for this year, giving it plenty of room to grow its payout, and certainly enough cushion to maintain it. And it has financial leeway to invest in impactful acquisitions such as its purchase of rare-disease drugmaker Alexion Pharmaceuticals for $39 billion, which closed a few months ago.

Alexion's revenue base grew 21.6% from 2019 to $6.1 billion last year, led by sales of Soliris, Ultomiris, and Strensiq. Its lineup will shore up AstraZeneca's existing rare diseases drug portfolio. Equally as important, the acquisition of Alexion added 30 research projects to an AstraZeneca pipeline that already included 160 projects. This wide portfolio of candidate drugs for a host of potential indications in areas such as oncology and immunology bodes well for AstraZeneca. And it's part of the reason why analysts are forecasting that it will grow earnings at an annualized rate of 20% annually over the next five years.

When you combine a sustainable payout ratio with tremendous earnings growth potential, it isn't hard to generate market-beating returns. And trading at a reasonable valuation of 19 times 2021's anticipated earnings, AstraZeneca seems well-positioned to beat the market in the years ahead. 

A doctor and patient speak with each other at an appointment.

Image source: Getty Images.

3. Merck

At current share prices, Merck (NYSE:MRK) pays a dividend that yields 2.9% -- more than twice the yield of the S&P 500. And similar to those of AbbVie and AstraZeneca, that payout appears to be safe. Merck's payout ratio based on its recent guidance will be around 46% this year. This strikes an appropriate balance between rewarding shareholders and investing in future growth.

Like AstraZeneca, Merck recently announced a big acquisition -- an $11.5 billion deal for Acceleron Pharma (NASDAQ:XLRN). Should the acquisition be approved by regulators, Merck would own the rights to royalty payments of 20% to 25% of net sales on Bristol Myers Squibb's (NYSE:BMY) anemia drug Reblozyl. That alone could amount to nearly $1 billion in annual revenue for Merck; Bristol Myers Squibb is forecasting peak annual sales of $4 billion for Reblozyl. 

Merck would also gain ownership of a highly promising candidate in late-stage clinical trials -- pulmonary arterial hypertension drug sotatercept. Wall Street expects that, if approved, sotatercept will generate peak annual sales of $2.2 billion. This could go a long way toward helping the company make up for the revenue it will lose when its top-selling and fast-growing cancer drug Keytruda loses patent protection in 2028. Year to date, Keytruda has provided 35.8% of Merck's total revenue.

Early indications suggest that Merck's efforts to build its post-Keytruda future will be successful. In the meantime, analysts believe it will grow EPS by 13% annually over the next five years. Given Merck's healthy earnings growth potential and its P/E ratio under 16, the stock still appears to be a solid biotech pick, even though it's trading near its 52-week high. 

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.