Merck Discloses Positive Data For Respiratory Syncytial Virus Antibody Treatment, Seeks FDA Nod For Broader Child Use

Merck & Co. (NYSE:MRK) on Thursday shared positive second RSV season findings from the Phase 3 SMART trial.

The results from the SMART trial were presented at the RSVVW Conference and will be shared with the U.S. Food and Drug Administration (FDA) for evaluation for an expanded indication in children at increased risk for severe Respiratory Syncytial Virus (RSV) disease.

New data from the SMART trial in children under 2 years of age showed that safety was generally consistent with safety observed in MK-1654-007 infants who received Enflonsia during the RSV season.

Enflonsia (clesrovimab), the monoclonal antibody being evaluated, is currently approved for use in infants during their first RSV season and aims to provide protection through five months.

In the trial, safety data showed consistency with previous findings, and the monoclonal antibody serum concentrations achieved were similar to those in healthy infants from earlier studies.

The data support the potential for Enflonsia to help protect vulnerable children who may require an additional dose for their second RSV season.

Interim data from RSV season 1 of the Phase 3 SMART trial — alongside data from the pivotal Phase 2b/3 CLEVER trial—supported the FDA approval of ENFLONSIA in June 2025 and subsequent global regulatory approvals.

On Wednesday, GSK plc (NYSE:GSK) shared new effectiveness data for AREXVY, an RSV vaccine, at the conference.

For GSK’s RSV vaccine, the study showed an association with 75.6% vaccine effectiveness (VE) against RSV-related hospitalization at a median follow-up of 5.6 months (maximum 9.7 months) post-vaccination.

Further exploratory endpoints showed an association with 63.1% VE against major adverse cardiovascular events.

Technical Analysis

The stock is currently trading 5.9% above its 20-day simple moving average (SMA) and 11.5% above its 100-day SMA, demonstrating longer-term strength. Shares have increased 42.13% over the past 12 months and are currently positioned closer to their 52-week highs than lows.

The RSI is at 69.29, which is considered neutral territory, while MACD is at 3.7853, above its signal line at 3.3955, indicating bullish momentum. The combination of neutral RSI and bullish MACD suggests mixed momentum.

• Key Resistance: $123.50
• Key Support: $120.00

Analyst Consensus & Recent Actions

The stock carries a Buy Rating with an average price target of $119.95. Recent analyst moves include:

• Guggenheim: Buy (Raises Target to $140.00) (Feb. 6)
• Citigroup: Neutral (Raises Target to $120.00) (Feb. 4)
• Cantor Fitzgerald: Neutral (Raises Target to $120.00) (Feb. 4)

MRK Price Action: Merck shares were down 0.03% at $121.62 during premarket trading on Thursday, according to Benzinga Pro data.

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