(Bloomberg) -- GSK Plc and Pfizer Inc. are on pace to sell a combined $2 billion of their new RSV vaccines for older adults this year, more than five times what analysts had expected, according to Bloomberg Intelligence.

Early data from US prescription sales for GSK’s Arexvy and Pfizer’s Abrysvo show the shots are in higher demand than expected, BI analyst John Murphy wrote in a research note. If that rate is sustained, up to 6.5 million patients will be injected this year in the US alone.

The two RSV vaccines for people 60 and older have been on the market for a little over two months after scientists worked for six decades to develop immunization against the common, but sometimes deadly, respiratory syncytial virus. Global sales for adult RSV shots are expected to reach $10 billion by 2032, according to Bloomberg Intelligence.

Analyst estimates of $340 million in 2023 revenue for both adult RSV vaccines “seems out of whack with the early prescription data we’ve analyzed,” Murphy writes in his research note.

In addition to the two adult vaccines approved for use this year, Pfizer, Sanofi and AstraZeneca Plc received US Food and Drug Administration approval for RSV immunizations for infants. 

GSK Beats Pfizer

In the US alone, Murphy expects GSK to sell about $1.1 billion of its adult vaccine in 2023, while Pfizer will bring in $680 million. Globally, analysts expect GSK revenue of $269 million from the shot this year, and Pfizer to only take in $71 million, a “stark contrast,” Murphy writes.

GSK is likely beating Pfizer due to a major ad campaign starring ex-NBA star Earvin “Magic’” Johnson and a simpler dosing process, Murphy writes. He said Pfizer may also be more focused on its much larger Covid-19 franchise.

Pfizer could use a win as it struggles with months of sluggish demand for its Covid products. Its shares have fallen 35% this year, the most among the five biggest US pharmaceutical companies. 

Discovered in 1956, RSV is a leading cause of infant hospitalization and can also prove dangerous for the elderly. The virus affects an estimated 64 million people globally and causes 160,000 deaths each year, according to the US National Institute of Allergy and Infectious Diseases.  

©2023 Bloomberg L.P.