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New RSV Vaccine Distribution: Who's At The Top Of The List?

As fall approaches, so does respiratory syncytial virus or RSV season. This year, there are more options for those most susceptible to RSV, including a new vaccine and updated RSV vaccine guidance for seniors.

Carina Marquez, MD, associate professor of Medicine in the Division of HIV, Infectious Diseases, and Global Medicine at Zuckerberg San Francisco General, Peter Chin-Hong, MD, professor in the UCSF Health Division of Infectious Diseases and Theodore Ruel, MD, chief of the Division of Pediatric Infectious Diseases and Global Health at UCSF Benioff Children's Hospitals, explain what we need to know about the RSV virus and vaccine.

What is RSV?

RSV is a virus that can cause lung and respiratory tract infections such as bronchiolitis and pneumonia. Most RSV infections clear up by themselves in a couple of weeks, but, for some people at high risk, it can cause serious illness leading to hospitalization or death.

Who is most vulnerable to RSV?

Premature infants, newborns and babies – especially those younger than 8 months.

Children younger than 2 years with chronic lung disease or congenital heart disease.

Children with neuromuscular disorders, including those who have difficulty swallowing.

Children of Native American descent.

Adults over 75.

Adults 60-74 with chronic medical conditions such as diabetes, heart or lung disease.

Anyone with a weakened immune system.

How do people contract RSV?

RSV spreads much like the common cold via droplets of saliva released into the air when sick people cough or sneeze. These droplets carry the virus, spreading it when they come in contact with our eyes, noses or mouths.

What are RSV's symptoms?

RSV symptoms are like those of a cold: congestion, fever, cough, wheezing and a sore throat. In young babies, RSV's only signs may be difficulty breathing, irritability and decreased activity. Older adults and babies younger than 6 months may need to be hospitalized if they have trouble breathing, become dehydrated or their symptoms worsen.

What vaccines are available to protect against RSV?

There are now three vaccines available for adults and one for those who are pregnant. This summer, the FDA approved Moderna's mRESVIA RSV vaccine for adults. Last year, the FDA approved Abrysvo (Pfizer) and Arexvy (GSK) to protect seniors from serious illness, and approved Abrysvo for pregnant women in their third trimester during the RSV season, to help safeguard newborns from the virus for up to 6 months. All three are single-shot vaccines.

Who should get vaccinated for RSV?

This summer, the CDC altered its recommended guidance to 75 years for all seniors who have not yet been vaccinated. It still recommends that seniors 60 to 74 get vaccinated if they are immune compromised or have chronic medical conditions and have not yet been vaccinated.

Pregnant women in their last trimester should talk to their health care provider about whether the vaccination is right for them.

How often should adults get the vaccine?

The RSV vaccine isn't needed annually like the flu vaccine, but only once.

What should I know about RSV prevention for infants?

There is no vaccine approved for babies at this time, but there are ways to prevent them from getting very sick:

Asking people sick with a cough and runny nose to wash their hands and avoid close contact with infants.

Vaccinating pregnant women with Abrysvo in their third trimester to stimulate their immune system to make antibodies against RSV. The antibodies pass to the fetus, protecting babies for the first 6 months of life.

Mothers who are not vaccinated can immunize vulnerable infants with Nirsevimab (Beyfortus), an anti-RSV antibody, that can prevent serious RSV in babies. Ask your doctor if your baby should get it.

How long will the new RSV vaccine protect seniors and infants from RSV?

For adults, RSV vaccines show continued protection even two years after immunization. Based on this, the CDC recommends only one dose of the RSV vaccine for seniors right now, but this may change in the future.

In infants, we know that the vaccine given to those who are pregnant protects babies for their first 6 months of life – when they are most at risk for the virus. Beyfortus, the new monoclonal antibody injection, similarly reduces the risk of RSV in infants for about five months – or one RSV season.

Does the new RSV vaccine have any side effects?

In adults, the most frequently reported side effects have been soreness at the injection site, muscle pain, fatigue, headache and joint pain. In the combined clinical trials of the vaccine, 20 out of more than 38,000 people who received the shot reported an abnormal heart rate about two weeks after vaccination. Eight people out of a similar number of folks in the trials who did not take the vaccine said the same. In addition, six people developed rare neurological complications.

Scientists are still figuring out if these irregular heartbeats or neurological complications were linked to the vaccine, but if you have concerns talk to your doctor. What is clear is that the benefit of being protected against RSV for many people far outweighs this possible risk because we don't have good therapies once people get seriously ill with RSV.

Can I take the RSV vaccine alongside flu or COVID-19 shots?

Yes, it is safe to get all three vaccines at the same time. However, it is up to the individual to assess if they will have a reaction to the vaccinations based on their previous history of vaccines. There is no minimum waiting time between doses.

Researchers Use Biophysics To Design New Vaccines Against RSV And Related Respiratory Viruses

In most people, the lung-infecting pathogens known as respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) trigger mild cold-like symptoms. But in infants and seniors, these viruses can cause severe pneumonia and even death.

Vaccines against both viruses, however, have been difficult to design. Now, Scripps Research scientists have analyzed the structure and stability of a critical RSV and hMPV protein to better design vaccines that target it. Their research, published in Nature Communicationson November 16, 2024, points toward RSV vaccines that may be more effective than existing ones, as well as a vaccine against hMPV, for which there are no commercially available options.

"Creating a combination vaccine for these viruses could significantly reduce viral hospitalizations for both babies and the elderly," says study senior author Jiang Zhu, PhD, an associate professor in the Department of Integrative Structural and Computational Biology at Scripps Research. "This could alleviate the overall health burden during flu season, which is also when most RSV and hMPV cases occur."

Scientists have long attempted to create vaccines that coax the immune system into recognizing the fusion (F) proteins present on the surfaces of RSV, hMPV and related viruses. These proteins play a key role in letting the viruses infect human cells. However, the F protein has a delicate structure that changes rapidly from a "pre-fusion" form to a "post-fusion" form when the viruses fuse with cells. Ideally, a vaccine would teach the immune system to recognize the closed pre-fusion F protein so it could stop infection.

"The problem is that this pre-fusion structure is so fragile and volatile," says Zhu. "If you change the environment even a tiny bit, the protein is like a transformer that suddenly flips from a car into a robot."

This means that scientists cannot simply use an isolated pre-fusion F protein as a vaccine -- its structure would change too quickly for the immune system to react. And a vaccine targeting the post-fusion version of the protein wouldn't teach the immune system to attack the virus before it has a chance to infect the body.

Zhu, who has a background in biophysics and has recently designed new vaccines for viruses including HIV, SARS-CoV-2 and hepatitis C, thought that if he could understand the precise mechanism of why the pre-fusion F protein was so unstable, especially why it is so easy to open, he could make a more stable form -- and, in turn, a better vaccine.

Zhu and his research team first analyzed the F proteins used in development of four existing RSV vaccines -- the commercially available Arexvy, mResvia and Abrysvo, and an experimental vaccine that has reached phase 3 trials. They discovered that some of the pre-fusion F proteins appeared to be unstable and sometimes converted to an open form, or even less desirable, a post-fusion form. A detailed structural analysis revealed an "acidic patch" sitting at the center of the pre-fusion structure with three positively charged molecules repelling each other, ready to push open the RSV F protein at the slightest perturbation, like a spring-loaded transformer.

"This is an incredible trait for a virus to acquire during evolution to control the movement of its key protein," says Zhu. "Luckily, it's also something we can overcome, either with brute force or, better, with a smart mutation directly tackling the source of the problem, the acidic patch."

Zhu reengineered the RSV F protein by changing a pair of molecules at its center, turning the outward repelling force into an attracting one. Then, his team showed that this new F protein was both more stable in the lab and successfully worked to vaccinate mice against RSV.

"This suggests that we might be able to take a similar approach for other viral F proteins," says Zhu. "At the very least, we can look for similar repulsive patches in their structure as we design vaccines."

In the hMPV F protein, Zhu didn't find the same patch of repellant molecules -- instead, he used a strong chemical bond as a "brute force" solution to hold the protein together. Once again, the modified protein was stable enough to remain intact as a vaccine.

In future studies, Zhu plans to develop an experimental vaccine using a self-assembling protein nanoparticle (SApNP) platform reported in his recent work to deliver the RSV and hMPV F proteins to the human body. "That would be our next-generation RSV/hMPV combo vaccine," says Zhu.

is work was supported by funding from Uvax Bio. Uvax Bio, a spin-off vaccine company from Scripps Research, employs proprietary platform technology invented in Zhu's lab to develop and commercialize prophylactic vaccines for various infectious diseases.

Some Hospitals Seeing Increase In RSV, 'walking Pneumonia.' Here's What To Know

Some hospitals in the U.S. Are seeing an increase in RSV and higher levels of "walking pneumonia" among young children despite overall respiratory illness activity remaining low nationally.

Cook Children's Medical Centers in Texas reported a "steep increase" in children visiting the emergency room due to respiratory-related illnesses.

On Tuesday, at the health system's Fort Worth location alone, there were 572 patients -- a near-record-high number -- in the emergency department. Officials said the increase in hospital visits is due to a spread of RSV and walking pneumonia in the Dallas-Fort Worth area.

MORE: Researchers investigate potential link between RSV and sudden unexpected infant deaths

Additionally, University of North Carolina hospitals reported 40 walking pneumonia cases in the last week of October compared to no cases the same time last year.

Infectious disease specialists say that although parents should stay alert when it comes to respiratory illnesses spreading, this season also may also be marking a return to typical seasons seen before the COVID-19 pandemic.

"It's the calm before the storm," Dr. Peter Chin-Hong, a professor of medicine and infectious disease specialist at the University of California, San Francisco, told ABC News. "It feels that there's so much going on … that we almost forget about respiratory viruses, but they're very regular. They're kind of falling back into normal pre-pandemic cadence."

Pneumonia-associated Emergency Department visits with M. Pneumoniae diagnosis graph (CDC)

Walking pneumonia seeing cyclical increase

So-called "walking pneumonia" is a respiratory tract bacterial infection caused by the bacteria Mycoplasma pneumoniae (M. Pneumoniae), according to the Centers for Disease Control and Prevention.

Infections are generally mild, and people may seem better than expected for those with a lung infection, hence the term walking pneumonia, the CDC said. Sometimes serious complications, however, emerge requiring hospitalization.

For the week ending Nov. 2, the latest for which CDC data is available, 2.8% of all pneumonia-associated ED visits led to an M. Pneumoniae diagnosis, up from just 2% at the end of September.

Rates were highest among those ages 1 and younger, making up 7.8% of all pneumonia-associated ED visits with an M. Pneumoniae diagnosis for the week ending Nov. 2.

MORE: COVID-19 infections during 1st wave linked to higher risk of heart attack and stroke: Study

Experts say mycoplasma infections have a cyclical nature and tend to surge every three to seven years.

"Just like other respiratory viruses, there was not a lot of exposure during the pandemic years because of social distancing and people staying away from each other, and so we're catching up to that," Chin-Hong said. "Mycoplasma may also be one of these things where you're kind of seeing the perfect storm. So, it comes back every four or five years and people are getting back to their normal lives."

RSV activity returning to pre-pandemic levels

Respiratory syncytial virus, or RSV, is a common respiratory virus with most children affected by their second birthday, according to the CDC.

Although it typically causes mild, cold-like symptoms and most people recover in one to two weeks, it can be a serious infection for infants and older adults, resulting in hospitalization, the CDC said.

Current levels remain lower than those seen at the same time during the past few seasons.

PHOTO: A mother holds a coughing child baby in undated stock photo. (Adobe Stock)

"While RSV activity is increasing in certain regions, particularly among young children, it's important to remember that we're seeing a return to more typical pre-pandemic patterns," said Dr. John Brownstein, an epidemiologist and chief innovation officer at Boston Children's Hospital and an ABC News contributor.

"This year's season is starting later and progressing more slowly compared to the past few years, which were marked by earlier and more severe outbreaks," he added.

Brownstein pointed out that while national levels remain low, certain regions in the southern U.S. And eastern U.S. Are seeing localized surges, especially among young children.

When to go to the emergency room

Chin-Hong said if symptoms are mild, including low-grade fever, dry cough, sore throat, headaches and mild aches and pains, parents can keep their children home and contact their primary care provider with any questions.

However, when symptoms become more severe including difficulty breathing, a long-lasting fever or lethargy, then it might be time to visit the emergency room.

MORE: Pediatric pneumonia cases are on the rise. Here's what parents should know

If you have "a child who's having a cough for more than seven days and maybe they're not shaking that off, then you worry about something like walking pneumonia," Chin-Hong said.

How to prevent RSV and walking pneumonia

To prevent RSV, there are three vaccines approved for adults ages 60 and older as well as some adults between the ages 50 and 59 who are at higher risk. There is also a vaccine available for pregnant women between 32 weeks and 36 weeks of pregnancy.

For babies under eight months, there are two monoclonal antibody products available. Monoclonal antibodies are proteins manufactured in a lab that mimic the antibodies the body naturally creates when fighting an infection.

"For walking pneumonia. Or mycoplasma, there's no vaccine for that, but by getting vaccines for RSV, COVID [and] influenza, you reduce the probability of co-infections that can make things worse," Chin-Hong said.

PHOTO: A box of RSV vaccine is displayed at a pharmacy in New York, Sept. 24, 2024. (Mary Conlon/AP)

Experts also recommended applying lessons learned during the COVID-19 pandemic, such as wearing a mask in spaces with poor ventilation.

"Practicing good hygiene, like frequent hand-washing and covering coughs and sneezes, remains essential in preventing the spread of respiratory infections," Brownstein said.

Some hospitals seeing increase in RSV, 'walking pneumonia.' Here's what to know originally appeared on abcnews.Go.Com

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