According to the latest data, the efficacy of the RSV vaccine introduced by Moderna (MRNA.US), a global leader in biotechnology known for its mRNA-based coronavirus vaccine, has dropped significantly in the second year, and its efficacy in the second year is lower than that of competing products of RSV vaccines under Pfizer and GlaxoSmithKline. This negative news also prompted Moderna's stock price to fall by more than 11% on Wednesday's regular trading hours in the US, and eventually closed with the same percentage drop.

This result may further cast doubt on the prospect of Moderna's RSV vaccine, which already ranks third in market share. Moderna's stock price fell by as much as 11%, making it the biggest drop in both the closing price and intraday decline since November last year.

A survey data released by the Centers for Disease Control and Prevention (CD) website in the US on Wednesday showed that the actual efficacy of Moderna's RSV vaccine for patients with at least three types of respiratory syncytial virus (RSV) 'lower respiratory tract' symptoms dropped from 55% in the first year to 36% in the second year.

The survey data also showed that the overall efficacy of Pfizer's RSV vaccine only dropped from 86% in the first year to 74% in the second year. Another report by the Centers for Disease Control and Prevention shows that the overall efficacy ratio of GlaxoSmithKline's RSV vaccine dropped from 79% to 59%, and both competitors' RSV vaccines are far more effective than Moderna's in both the first and second years of effectiveness.

Michael Yee, an analyst at the Wall Street giant Jefferies, said in a research report that Moderna's new data is 'in the expected low-end numbers', and pointed out that different pharmaceutical or biotech companies often study RSV vaccines at different times of the year, making it difficult to make exact comparisons.

At a meeting of the Centers for Disease Control and Prevention Committee, Moderna also presented the latest research data on its respiratory syncytial virus (RSV) mRNA vaccine mRESVIA, and the meeting made some suggestions on how to use the vaccine.

Last month, Moderna's RSV vaccine specifically for the elderly received formal approval from the U.S. government for use in protecting adults aged 60 and over from lower respiratory tract diseases caused by RSV infections. As the company seeks to break free from its extreme dependence on the shrinking coronavirus vaccine market, this move provides the company with a second flagship product.

As the emergency phase of the COVID-19 pandemic comes to an end, Moderna has been working to reassure investors that it is pivoting to its new products based on innovative mRNA technology, such as cancer vaccines developed in collaboration with US pharmaceutical giant Merck (MRK.US) and the recently approved RSV vaccine.

A Moderna spokesperson said that immunity to RSV is not lifelong, and like all approved RSV vaccines, mRESVIA showed a gradual decrease in efficacy over time.