There's a lot of optimism that the economy and day-to-day life will get back to normal next year now that there are multiple vaccines showing a high rate of efficacy in preventing COVID-19. However, there's no guarantee how things will play out in 2021 and especially given how unpredictable this past year has been, investors may want to stick to low-risk investments that can do well under many different scenarios to keep their portfolios safe.

Two safe stocks you can buy today include Abbott Laboratories (ABT 0.37%) and Microsoft (MSFT -0.32%). Their businesses have done well over the years, including during the pandemic, and will likely continue doing so for the foreseeable future. Here's why they're optimal buys for risk-averse investors.

Are you diversified written in a notebook.

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1. Abbott Laboratories

What conservative investors will like about Abbott Laboratories is the company's versatility. The Illinois-based business has booked $23.9 billion in revenue through the first nine months of 2020, and that's 1.3% higher than the $23.6 billion it recorded in the same period last year. Net earnings of $2.3 billion remain strong but are down 11.6% from a year ago.

Although hospitals are deferring procedures to help manage COVID-19, Abbott's business has adapted to that. Sales in its pharmaceutical division are down 4.7% this year and medical device revenue has fallen 5.6%. However, nutritional sales are up 3.1% and Abbott's sales from its diagnostics segment have risen by 14.2%. The company is well-diversified, and that's what makes it a resilient investment to hold in both good times and bad.

One of the ways Abbott has adapted to the pandemic is by developing various COVID-19 tests, including one that costs just $5 and can deliver results in 15 minutes. Most recently, the Food and Drug Administration approved a $25 antigen test from Abbott that people can use at home, which can also produce rapid results. The company estimates that in the first quarter of next year it will ship out 30 million of the tests and another 90 million the following quarter. 

Abbott's in a great position to do well next year, whether or not things go back to normal. Either way, its COVID-19 tests are likely to be in demand as people stay safe. And in a best-case scenario where hospitals resume normal operations, its medical device sales should also get a boost. The healthcare stock also makes for a stable dividend investment, as it is a Dividend Aristocrat that has increased its payouts for 49 years in a row and today yields 1.7% -- just slightly below the S&P 500 average of 1.8%. 

Year to date, the stock is up 24% and is outperforming the index, which has rallied 14%.

2. Microsoft

A good tech stock that you can rely on to do well next year is Microsoft. The Washington-based business is seeing continued demand for its services this year as companies are doing more work remotely and relying on the cloud. Although its revenue from search ads is down over the past two quarters, its cloud business Azure still grew at a rate of more than 40% year over year during that time, and sales from its Office 365 commercial products are still rising at around 20%.

Overall, Microsoft's sales of $37.2 billion in the first quarter of fiscal 2021, for the period ending Sep. 30 (which it released on Oct. 27), grew at a rate of 12% from the prior-year period. That's down slightly from the 13% growth it achieved in the previous quarter. Meanwhile, the company's bottom line continues to be strong, with Microsoft reporting profit margins of at least 29% in each of the past four quarters.

The tech giant's products will be in demand whether people are working from their offices or from their homes next year. And that's what makes Microsoft a safe bet to do well in any scenario in 2021. In the best-case scenario where companies are recovering and spending more money on ads, its search-related revenue should bounce back, and that will give its top line an added boost. 

Although Microsoft isn't a Dividend Aristocrat, it can also be a solid investment that gives you some recurring dividend income to add on top of the capital gains you're likely to earn from owning the stock. Year to date, shares of Microsoft are up over 42% and its dividend yields right around 1% per year.