Growth stocks are supposed to, well, grow. That's especially the expectation when the overall stock market soars as it did in 2023.

However, even the best growth stocks can experience rough patches. Those periods, though, can present excellent buying opportunities for long-term investors. Here's one growth stock down 79% that's a screaming buy right now, according to several Wall Street analysts.

Renewed bullish views about this biotech stock

It doesn't seem all that long ago when Moderna (MRNA 1.69%) was flying high. The company's rapid development of a messenger RNA (mRNA) vaccine for COVID-19 captured investors' attention. Between the beginning of 2020 and September 2021, Moderna's share price skyrocketed more than 22x.

Then the bottom fell out. The biotech stock has plunged 79% from its high mark. Over the last 12 months, while the overall stock market was booming, Moderna's shares sank nearly 50%.

However, there are now several Moderna bulls on Wall Street. Oppenheimer analyst Hartaj Singh upgraded the stock to outperform earlier this month. RBC maintained its outperform rating for Moderna a little over a week later. Ten analysts surveyed by LSEG in December recommended the stock as a buy or strong buy.

Sure, some on Wall Street are less enthusiastic about Moderna. One especially pessimistic analyst set a price target 40% below the biotech's current share price. That's an outlier, though. The average 12-month price target for Moderna reflects an upside potential of 28%.

Moving beyond COVID

The renewed optimism on Wall Street about Moderna isn't due to the company's COVID-19 vaccine. Instead, analysts are excited about the company's pipeline prospects.

Moderna hopes to win regulatory approvals for its respiratory syncytial virus (RSV) vaccine beginning in the first half of this year. The company won't be the first to market: Pfizer and GSK won U.S. approvals for their respective RSV vaccines in 2023. However, Moderna could be a strong contender in the RSV market.

Oppenheimer's Singh looks for Moderna to win approvals for its flu vaccine and personalized cancer vaccine in 2024 or 2025, as well. Last year, Moderna reported late-stage clinical results showing that its experimental flu vaccine produced a stronger immune response than Fluarix, a flu vaccine that's already on the market. Likewise, Merck and Moderna have announced encouraging results from a phase 2b study of a combination of Moderna's mRNA-4157/V940 personalized cancer vaccine and Merck's Keytruda immunotherapy.

COVID-19 will remain important to Moderna, though. Oppenheimer predicts that 2024 will be a trough year for the biotech's COVID revenue, with sales rising in 2025. Moderna also is developing a next-generation COVID vaccine and a COVID-flu combo vaccine that it expects to launch in 2025.

Are the Wall Street bulls right about Moderna?

Some analysts have been wrong about Moderna before. Are the Wall Street bulls right about Moderna now? I think they just might be.

Moderna expects its COVID franchise to be profitable this year and going forward. Management believes that the company will return to sales growth in 2025. And they're expecting to reach breakeven in 2026.

The biotech's late-stage pipeline programs hold the potential to generate combined peak annual sales of at least $10 billion. Moderna's market cap currently stands at $38 billion. The stock's valuation looks attractive based on its realistic growth prospects.

In addition, Moderna's pipeline features 30 programs in phase 1 and phase 2 studies. The company's outlook could grow even brighter as these programs advance in clinical testing.

Moderna is probably still too risky for conservative investors. For aggressive investors, though, the biotech's rough patch could present a compelling buying opportunity.