What happened

Shares of Moderna (NASDAQ:MRNA) were sliding 4.5% lower as of 3:39 p.m. EDT on Thursday after falling as much as 9% earlier in the day. The decline came after STAT News reported the company's planned late-stage study of COVID-19 vaccine candidate mRNA-1273 could be delayed.

So what

How bad is the latest news for Moderna? It doesn't appear to be anything for investors to be overly concerned about.

Moderna stated last month that it expected to begin a phase 3 study of mRNA-1273 in July. The biotech is making changes to the trial plan that will push back the anticipated start date, according to the STAT News report. These types of changes to trial plans are routine.

A healthcare professional places a cotton swab on a person's arm with one hand while holding a syringe in the other.

Image source: Getty Images.

The delay apparently won't be a long one. Moderna tweeted earlier today: "The trial is still expected to begin in July and we expect to be the first to start a Phase 3 trial."  

Beginning the late-stage study later than expected means the trial will also end later than hoped. This pushes back how quickly Moderna could potentially win regulatory approval for mRNA-1273 and begin marketing the vaccine. However, it doesn't alter Moderna's prospects in any significant way.

Now what

The main thing for investors to watch now are the results from Moderna's phase 2 study of mRNA-1273 and the now-delayed start for its phase 3 study. The biotech stock is likely to be highly volatile until preliminary results from the late-stage study are available later this year.