What happened

Shares of Moderna (MRNA -0.74%) were sliding 3.8% lower as of 11:26 a.m. EDT on Friday. The decline came even with a positive development for the company. The European Union is allowing the production of Moderna's COVID-19 vaccine to continue at a facility in Spain operated by the company's partner, Rovi. Contamination in some doses of the vaccine shipped to Japan was linked to a potential manufacturing issue at Rovi's plant.

However, EU regulators continue to investigate the contamination issue. Investors may be afraid that more problems could be found that could disrupt the production of Moderna's SpikeVax vaccine. 

Close-up of vaccine vials.

Image source: Getty Images.

So what

Any production delays could hurt Moderna's vaccine sales. However, there's no reason to expect any manufacturing hold-ups at this point.

The contamination problems weren't as bad as they could have been. Although Japan suspended the use of 1.63 million doses of Moderna's COVID-19 vaccine, no safety issues have been reported so far. 

Probably the main challenge for Moderna is that the vaccine stock is priced for perfection. Any concerns can give investors a reason to sell, creating downward pressure on the share price.

Now what

The European Medicines Agency will likely be able to determine the root cause of the contamination issues relatively quickly. That could put the problem to rest for Moderna -- or create even more headaches for the company.