RSV Vaccine Update Rattles Pharma Stocks – GSK.L, PFE, MRNA

Following recent guidance from U.S. health authorities on the administration of respiratory syncytial virus (RSV) vaccines, shares of pharmaceutical companies took a hit. GlaxoSmithKline PLC (LON:GSK), a major vaccine manufacturer, experienced a 6% drop in shares as a result of the new recommendations by the U.S. Centers for Disease Control and Prevention's advisory committee on immunization practices (ACIP).

Pfizer (NYSE: PFE) and Moderna (NASDAQ: MRNA), both of which are also in the RSV vaccine market, did not escape the ripple effect, with their shares falling by 2% and 11% respectively. The ACIP has voted to recommend restricting RSV vaccine doses to a specific age group of 60-74 year olds deemed to be at risk, while greenlighting the vaccine for all those aged 75 and older.

Industry analysts at Jefferies have raised concerns about the potential impact of these guidelines, suggesting a considerable reduction in the target market for RSV vaccines. Initial estimates projected an addressable market of approximately 80 million people aged 60 and above. However, the post-recommendation figures could see this number shrink to around 55 million.

The ACIP’s recommendation was unanimous concerning adults aged 75 and older, who are now endorsed to receive a single dose of RSV vaccine. Moreover, adults aged 60-74 who are at an increased risk of severe RSV are also advised to receive a single vaccine dose. Despite evidence indicating that the vaccine does not statistically elevate the risk for Guillain-Barré syndrome (GBS), a neuroinflammatory condition, the ACIP opted for a cautious approach.

The efficacy of GSK's Arexvy vaccine, which promises a 67%-75% protection rate, is a ray of hope, yet it is shadowed by the committee's decision to defer approval for at-risk individuals aged 50-59 until more data on the association with GBS is available. Moderna's RSV offering, on the other hand, has demonstrated a 50% trajectory of protection.

This development suggests that RSV vaccine makers will need to recalibrate their marketing and distribution strategies in light of the ACIP's rulings, which appear to be guided by a principle of prudence in the face of potential health risks, even when statistical evidence doesn't substantiate significant concern. As the pharmaceutical industry keeps a close eye on the unfolding situation, adjustments in market forecasting and patient outreach programs seem imminent to align with the ACIP's latest stance on RSV vaccination.