A new peer-reviewed study has found that the RSV vaccine is highly effective in protecting older adults against severe disease, hospitalization, and death. Along with a previous study that established the RSV vaccine is effective against hospitalization, this should provide more incentives for seniors to get the vaccine.

This post will examine the new study and provide the key results. Spoiler alert — the RSV vaccine saves lives.

What is RSV or respiratory syncytial virus?

The respiratory syncytial virus (RSV) is a common, contagious virus that causes respiratory tract infections. It is a single-stranded RNA virus whose name is derived from large cells known as syncytia which form when infected cells fuse.

It usually causes mild, cold-like symptoms. But it can cause serious lung infections, especially in infants, older adults, and people with serious medical problems. For seniors, RSV infections are dangerous as immune systems weaken.

RSV spreads from person to person through:

• The air by coughing and sneezing.
• Direct contact, such as kissing the face of a child who has RSV.
• Touching an object or surface with the virus, then touching your mouth, nose, or eyes before washing your hands.

RSV can sometimes lead to pneumonia (infection of the lungs) and congestive heart failure (when the heart can’t pump blood and oxygen to the body’s tissues).

According to the CDC, each year in the United States, RSV leads to approximately—

• 2.1 million outpatient visits among children younger than 5 years old
• 58,000 hospitalizations among children younger than 5 years old
• 177,000 hospitalizations among adults 65 years and older
• 14,000 deaths among adults 65 years and older

I know these numbers pale next to COVID-19, but before the pandemic, an RSV vaccine was often at the top of the wish list for a new vaccine. And for those people who had children or parents who had to deal with a serious RSV case, they probably wish there was a vaccine too.

There are three vaccines currently approved for use in the USA:

• Pfizer’s Abrysvo.
• GSK’s Arexvy.
• Moderna’s mRESVIA.

The CDC recommends a single dose of RSV vaccine for all adults age 75 and older, as well as for those ages 60 to 74 years at increased risk for severe RSV disease. All three of the above vaccines are approved for use in older adults.

The CDC also recommends one dose of maternal RSV vaccine during weeks 32 through 36 of pregnancy, administered from September through January. Pfizer Abrysvo is the only RSV vaccine recommended during pregnancy.

RSV vaccine is effective in preventing severe disease

In a paper published on 19 October 2024 in the respected journal Lancet, Amanda B Payne, PhD, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, and colleagues examined electronic health records-based network in eight states in the USA, including hospitalizations and emergency department encounters with respiratory syncytial virus-like illness among adults aged at least 60 years who underwent respiratory syncytial virus testing from Oct 1, 2023, to March 31, 2024. RSV vaccine status at the time of the encounter was derived from electronic health record documentation, state and city immunization registries, and, for some sites, medical claims. 

The researchers analyzed 28,271 hospitalizations for RSV-like illness among adults aged at least 60 years without immunocompromising conditions.

Here are some of the key results from the study:

• The RSV vaccine was approximately 80% effective against RSV-associated hospitalizations.
• The RSV vaccine was approximately 81% effective against RSV-associated critical illness (ICU admission or death, or both).
• Among 8,435 hospitalizations for RSV-like illness among adults with immunocompromising conditions (such as diabetes), vaccine effectiveness was 73% against associated hospitalization.
• The vaccine was 77% effective against respiratory syncytial virus-associated emergency department encounters.

The authors concluded:

Respiratory syncytial virus vaccination was effective in preventing respiratory syncytial virus-associated hospitalisations and emergency department encounters among adults aged at least 60 years in the USA during the 2023–24 respiratory syncytial virus season, which was the first season after respiratory syncytial virus vaccine was approved.

Summary

This is just more powerful evidence that, for people over the age of 60, the RSV vaccine is highly effective in preventing the more serious complications of respiratory syncytial virus infections.

Some people will state that the vaccine is “only” around 80% effective, as a reason to avoid the vaccine. This is part of the Nirvana fallacy which says if it’s not 100% perfect, it’s useless. No vaccine is 100% effective, and there probably will never be a 100% effective vaccine, although many are close.

The annual cost of RSV hospitalization for adults in the U.S. is estimated to be between $1.2 and $5 billion. Preventing up to 80% of hospitalizations with the RSV vaccine could result in major savings for consumers and the health system. Sounds good to me.

Citations

• Payne AB, Watts JA, Mitchell PK, Dascomb K, Irving SA, Klein NP, Grannis SJ, Ong TC, Ball SW, DeSilva MB, Natarajan K, Sheffield T, Bride D, Arndorfer J, Naleway AL, Koppolu P, Fireman B, Zerbo O, Timbol J, Goddard K, Dixon BE, Fadel WF, Rogerson C, Allen KS, Rao S, Mayer D, Barron M, Reese SE, Rowley EAK, Najdowski M, Ciesla AA, Mak J, Reeves EL, Akinsete OO, McEvoy CE, Essien IJ, Tenforde MW, Fleming-Dutra KE, Link-Gelles R. Respiratory syncytial virus (RSV) vaccine effectiveness against RSV-associated hospitalisations and emergency department encounters among adults aged 60 years and older in the USA, October, 2023, to March, 2024: a test-negative design analysis. Lancet. 2024 Oct 19;404(10462):1547-1559. doi: 10.1016/S0140-6736(24)01738-0. PMID: 39426837.