Navigating RSV protection this fall
Everything we learned the past year
Last year was the first time we had RSV vaccines and preventive monoclonal antibodies for a subset of people—pregnant women, older adults, and babies. This is a huge deal, as RSV poses a massive burden on health, health systems, and individuals every year.
While clinical trial data blew expectations out of the water, “real-world” data after a vaccine roll-out can be different because it’s not happening in a tightly controlled environment, and many more people are getting it.
So, how do vaccines and monoclonal antibodies function in the “real world”? And what do you need to know for this season?
TLDR: RSV protection is effective and much safer than getting the disease. There is an unanswered safety signal for those over 60, which may change your risk-benefit calculus. Forward this email to your pregnant friends and older family, as knowledge about this protection is low, and uptake is suboptimal.
Protection for infants
RSV disease is a big deal for kids under 5. The hospitalization rate alone is far higher than for flu or Covid-19.
Thankfully, parents have one of two choices to protect their little ones this fall:
Option 1: Vaccine during pregnancy (called Abrysvo)
The vaccine was highly effective in clinical trials—82% effectiveness against hospitalization within 3 months and 69% within 6 months after birth.
Unfortunately, we don’t have real-world data yet. (We looked!) This is because uptake was so low—effectiveness is hard to measure precisely with few people.
It’s safe. Specifically, there is no increased risk of preterm birth.
Preterm births were followed extra carefully after licensure because of some weird data during the clinical trial: a numerically (but not statistically) higher (1%) risk of preterm births driven almost entirely by the data from one specific site that participated in the clinical trial: South Africa. There’s a lot of speculation about why, but experts think it is an interaction between the vaccine, the immune system, and an environmental factor (like previous infection).
This past season, though, we got good news: A study looked at 2,973 U.S. women who delivered during the 2023 to 2024 season. They found:
No increased risk of preterm birth based on maternal vaccination status: 5.9% among vaccinated women and 6.7% among unvaccinated women.
CDC still recommends vaccination between 32 and 36 weeks of gestation during the RSV season, which would minimize risk. (Most preterm births in the South Africa study happened with vaccination before 32 weeks.)
Option 2: Monoclonal antibodies
Beyfortus (nirsevimab) is not a vaccine, i.e., it doesn’t teach the body to make an immune response. Rather, it is a preventive medication, providing antibodies directly and proactively.
Real-world data this past year showed that severe RSV in infants was drastically reduced among infants who got Beyfortus:
One study found 80% effectiveness in reducing hospitalization.
Another study found 98% effectiveness.
Americans over the age of 60
Many people don’t realize that RSV can impact older adults. Interestingly, RSV disease (without a vaccine) seems a more severe disease than Covid-19 or influenza among patients vaccinated for those diseases.
RSV vaccines are very effective.
The first real-world evidence was published last week for those over 60 years of age. And it was great news! Real-world data shows that the vaccines are highly effective:
Out of 28,271 RSV hospitalizations among adults at least 60 years of age, vaccine effectiveness was 80%.
You probably won’t need a booster for a few years.
If you got a vaccine last year, you don’t need one this year. Evidence presented at a CDC meeting a few months ago showed that a booster doesn’t meaningfully improve protection after two years.
A more recent update from the vaccine manufacturer found that protection is relatively durable for three years. However, there were signs of waning (down to 49% efficacy at Year 3). This likely means a booster may be in your future, just not right now. With new vaccines, we are at the mercy of time to see how they hold up.
People over 60 can get the RSV shot. Those over 75 should.
Last season, the recommendation was that those over 60 should get the vaccine. Now, that policy has softened. Why?
The change is mainly around a question about Guillain-Barre syndrome (GBS)—an autoimmune condition in which the immune system attacks the nerves. During the clinical trial, GBS occurred more often among those who got a vaccine than a placebo. But it was rare, so scientists didn’t know whether it was a “true” safety signal.
Unfortunately, the real-world data is still unclear. One of our three vaccine monitoring systems in the “real world” (Vaccine Safety Datalink) confirmed a safety signal this past year, but the other two didn’t.
With this in mind, CDC recently ran risk/benefit analyses for different age groups and comorbidities (which can make viral infections worse). The risk/benefit calculus among 60-74-year-olds without a comorbidity was tight, as shown in the slide below.
So the policy was changed: 60-74-year-olds can get the vaccine but should talk to their healthcare providers to make the decision together.
Bottom line
Real-world data from the past year confirmed clinical trials: RSV protection is effective at reducing severe disease and, in many cases, much safer than getting the disease itself.
Forward this email to your pregnant friends and older family, as knowledge about this protection is low, and uptake is suboptimal.
Love, YLE
“Your Local Epidemiologist (YLE)” is founded and operated by Dr. Katelyn Jetelina, MPH PhD—an epidemiologist, wife, and mom of two little girls. The main goal of this newsletter is to “translate” the ever-evolving public health science so that people will be well-equipped to make evidence-based decisions. This newsletter is free to everyone, thanks to the generous support of fellow YLE community members. To support this effort, subscribe below:
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Thank you for this post. A question: You say, "The risk/benefit calculus among 60-74-year-olds without a comorbidity was tight, as shown in the slide below." Could please elaborate on that? Exactly what the slide is showing --- the various numbers in the horizontal axis, the "lower bound" reference --- is not clear to me. Thank you.
Sad to say, about consulting with your doctor, when I indicated to my PCP that I and my spouse planned to get the RSV vax this year (I am 75, my spouse is 76), my doctor offered no information pro or con, so, unbeknownst to me, I was flying blind. I wasn’t advised 1) about the GSB possibility at all, let alone receiving information of level of risk; 2) that there was more than one choice of vaccine, let alone anything about possible differences among them; 3) the current status of when or whether to get a booster. If I had known what I read in Ryan McCormick’s post on RSV at the time, I would have chosen against getting the vaccine because of the GSB possibility, until and unless I was able to get clear information from my PCP. I don’t place blame on the PCP for this: Ryan has written how difficult it is to fit all the things expected of a primary care doctor into a single visit—particularly with older people who may have multiple things going on. I’d be interested in anyone’s thoughts about how PCPs could be better supported to make such consults possible. One that occurs to me is for the health care site to prepare a flyer that can be handed to each patient, with a brief explanation of key points about which to be aware. I’d be very interested in thoughts and suggestions from Team YLE and PCPs.