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How to Avoid a Respiratory Disease Tripledemic

October 4, 2023

What will this respiratory virus season look like? The odds of a tripledemic of COVID-19, influenza, and respiratory syncytial virus (RSV) are not zero. However, the good news is that we have a one-word way to lower the odds: vaccines.

The three diseases and their vaccines differ from each other, so here’s a primer to walk you through each of them. 

RSV: RSV is a common infection that affects the respiratory tract. For otherwise healthy people, it usually just causes mild, cold-like symptoms. Even though RSV is not as deadly as COVID-19 or influenza, it gets little public notoriety. In the U.S. each year, RSV still causes up to 80,000 hospitalizations and 300 deaths in children younger than five and up to 160,000 hospitalizations and 10,000 deaths among adults older than 65.

New tools are emerging to prevent RSV in these vulnerable populations, and they may last longer than one season. For example, a long-acting monoclonal antibody product can protect infants and young children. Monoclonal antibodies, proteins made in a lab, stimulate the immune system to fight an infection. The U.S. Centers for Disease Control and Prevention (CDC) recommends the immunization for all infants younger than eight months old entering their first RSV season and children ages 8–19 months who are at increased risk because, for example, they are immunocompromised. There is also a new RSV vaccine that is recommended for persons who are 32-36 weeks pregnant during the respiratory virus season (typically September through January) to protect newborns from severe RSV illness.

Adults 60 and older can choose between two new vaccines. CDC recommends that this age group receive a single dose of one of the vaccines based on shared clinical decision-making, that is, after consultation with a healthcare provider. Why recommend a consult rather than simply recommending everyone in this age group be vaccinated? Because of gaps in the evidence from clinical trials. They showed that the vaccines worked well in preventing lower respiratory tract disease. But the trials lacked data on vaccine efficacy among the highest risk adults such as those with underlying illnesses and those in nursing homes. And a few people developed medical conditions after vaccination, though it’s unclear if the vaccine caused those conditions. So the CDC prudently followed the evidence—what it knew and what it didn’t know. Though a consequence of this is that some insurers may not cover RSV vaccinations because it was not a blanket recommendation.

How do we find out more about the RSV vaccine and how well it works in all kinds of older adults? We need more data not only from clinical trials but also from real-world settings.

Our coordination of the CDC-funded Nursing Home Public Health Response Network, a group of eight academic sites and their related clusters of nursing homes, might be a start. The network is examining SARS-CoV-2 in its nursing homes and is well positioned to expand its work to study the use and outcomes of RSV vaccination in this highly vulnerable population. 

Abt also has done such studies for influenza and COVID-19 in other populations. We have monitored influenza vaccine effectiveness for nearly a decade in healthcare personnel, pregnant people, and children. And we tracked COVID-19 transmission and later vaccine effectiveness for CDC for older adults in retirement communities, older adults in hospitals, first responders and essential workers, households, pregnant people, and children.

COVID-19: The current spike in hospitalizations and deaths from COVID-19 in the U.S. prompted a lot more attention than RSV. Hospitalizations tripled from around 6,300 per week in late June to around 20,000 in early September, still well below the 44,414 at the start of the year and the 150,674 at the peak in January 2022. Deaths rose from around 500 per week in early July to more than 1,000 in early September. Those mortality figures are dwarfed by the 25,000 weekly deaths in January 2021. 

As has happened so often, new variants—EG.5 and BA.2.86—are receiving a lot of attention. EG.5 is highly transmissible and evades the immunity people get from previous COVID-19 infections and vaccinations, but the symptoms are like those of previous variants. BA.2.86 is genetically different from previous strains and, like EG.5, may be able to infect people who previously had COVID-19 or a vaccination.

Fortunately, updated vaccines by ModernaTX Inc. and Pfizer Inc. provided the same protection against these variants in clinical trials that previous vaccines provided against earlier mutations. “This suggests that the vaccines are a good match for protecting against the currently circulating COVID-19 variants,” the Food and Drug Administration (FDA) said in approving the vaccines.

CDC recommends the updated vaccines for everyone six months and older. It also notes that older adults and persons with weakened immune systems are at greatest risk for hospitalization and death. In addition, healthy children and adults can still get a severe case of COVID-19. The original COVID-19 vaccine had a 76 percent effectiveness rate in preventing the need for ventilators and death. The bivalent vaccines were 62 percent effective among adults without immunocompromising conditions in preventing COVID-19–associated hospitalization during the first 7–59 days after vaccination.  

Influenza: Flu season is upon us, and vaccine makers have made a couple of adjustments in anticipation of the flu strains that are likely to emerge. The FDA makes its vaccine approval decisions based on the World Health Organization analysis of strains that circulate in other countries before winter in the U.S. Vaccines reduce the risk of flu illness requiring a doctor’s visit by between 40 percent and 60 percent among the overall population, according to CDC. That greatly reduces the number of hospitalizations and deaths. The vaccines work better against some viruses [influenza B and influenza A(H1N1)]  than against others [influenza A(H3N2)].

What determines effectiveness? A big factor is whether the vaccine matches the circulating version of the flu. That said, vaccines can lower the risk of severe illness and lower the risk of worsening chronic conditions such as heart disease, lung disease, and diabetes. Vaccinations can help pregnant people avoid serious illness and protect their newborns for several months. And they can reduce the risk of life-threatening illnesses for children.

Conclusion: The risk of a tripledemic is far from zero. Lack of insurance coverage—and lack of knowledge about the RSV vaccine’s existence—may limit the number of people who get the protection. There is also still pervasive anti-vaccine sentiment, which could limit uptake of all three vaccines.

Yet vaccines are unquestionably our best bet. CDC recommends taking the flu and COVID-19 vaccines together and the RSV shot two weeks before or after. And don’t forget other preventive measures: washing hands, staying home if you’re sick, covering sneezes and coughs, and wearing a mask. And if you catch something, make use of the available treatments. Using the entire arsenal is the best way to reduce the chances we have multiple respiratory ailments everywhere all at once.

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