Pfizer and its partner BioNTech, Moderna, and Johnson & Johnson all have COVID-19 vaccines on the market in the U.S. already. However, there's another company hoping to join them, and its stock has outperformed all of theirs since the pandemic began, and in 2021 alone. 

Ocugen's (OCGN -5.98%) share price has quadrupled so far this year. But in the wake of that surge, is this high-flying biotech stock still a smart pick to buy? Here are two reasons to avoid Ocugen stock -- and one reason to consider buying it.

Tiny shopping cart with three vaccine vials and a syringe in it and two vaccine vials next to the cart

Image source: Getty Images.

Potential hurdles between the vaccine and the U.S. market

Many investors are betting that Ocugen will easily win emergency use authorization (EUA) from the Food and Drug Administration for Covaxin, the COVID-19 vaccine developed by the company's India-based partner, Bharat Biotech. That could be a risky bet.

Several news organizations reported on Tuesday that Ocugen had submitted a master file to the FDA that included preclinical study, chemistry, manufacturing, controls, and clinical study data for Covaxin. This submission was reportedly made to lay the groundwork for an EUA filing.

However, there are some potential hurdles between Covaxin and an EUA. First, Ocugen's still waiting on final data from Bharat's late-stage studies of Covaxin. That data has been delayed because of the severe intensification of the COVID-19 outbreaks in India. Second, there's no guarantee that the FDA will grant an EUA based on those clinical trials, which were conducted in India.

Perhaps coincidentally (but perhaps not), the FDA released revised guidance on Tuesday that stated that it "intends to decline to review and process EUA requests" where the agency can't verify product quality or the conduct and integrity of clinical trials. The FDA also said that it may decline to review EUA requests from companies that haven't "engaged in an ongoing manner with the Agency during the development of their manufacturing process and clinical trials program."

It's got a serious late-mover disadvantage 

Let's suppose, though, that the Covaxin data does satisfy the FDA, and the vaccine is given an EUA. All would be well, right? Not so fast. Perhaps the biggest risk for Ocugen is that it faces a distinct late-mover disadvantage in the U.S. market.

The U.S. government has already secured contracts from other sources for enough COVID-19 vaccine doses to fully inoculate all Americans in 2021. The best option for Ocugen would be to land a supply deal with the U.S. for 2022 and beyond. However, that won't be a slam dunk.

The European Union has already signed an agreement with Pfizer and BioNTech to supply it with vaccine doses through 2023. Don't be surprised if the U.S. follows suit with similar long-term arrangements with vaccine makers that have already won EUAs, and that have demonstrated that they can meet delivery commitments. This could leave Ocugen out in the cold.

One reason to consider Ocugen

Why consider investing in Ocugen now, with the odds seemingly stacked against it? Probably the best reason to keep the biotech stock in mind is the potential that Covaxin could be highly effective against coronavirus variants of concern. 

Research conducted by the Indian Council of Medical Research's National Institute of Virology found that, in preclinical studies, Covaxin showed promise in neutralizing the U.K. variant, the Brazil variant, and the double-mutant India variant that is currently ravaging that country. Ocugen thinks that the vaccine could potentially be effective against other emerging coronavirus variants of concern as well.

It's likely that future booster doses will need to target these variants. If Covaxin demonstrates that it's particularly effective against them in real-world conditions, that could at least give Ocugen a shot (no pun intended) at carving out a place for its vaccine in the U.S. market over the long term.

To be sure, that degree of efficacy against variants hasn't been conclusively established yet. Remember, too, that other drugmakers are busy testing variant-specific versions of their COVID-19 vaccines, and some of those could be even more effective than Covaxin.

The bottom line is that Ocugen is a speculative stock at this point with some major hurdles to jump before it can achieve commercial success.