Respiratory Viruses: RSV and Influenza Outlook and Recommendations 

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Influenza virus, respiratory syncytial virus (RSV), SARS CoV-2, and other seasonal viruses that circulate heavily in the fall and winter cause significant morbidity and mortality. Each season is slightly different, depending on the strains of the viruses circulating and immunity to the viruses. This year, the CDC predicts the severity of the respiratory virus season will be similar to last year, but more severe than pre-pandemic levels, estimated by the number of hospitalizations due to severe disease caused by influenza, RSV, and SARS CoV-2.  

A recent webinar hosted by the Emory University Project ECHO featured experts from the Centers for Disease Control and Prevention (CDC), Emory Healthcare, and Children’s Hospital of Atlanta who explained how the respiratory disease season is shaping up, the importance of vaccines, and clinical care guidance for adults, children, and pregnant patients. Listen to the recording and download the slides.

RSV Outlook and Vaccine Recommendations 

About RSV 

RSV is a common respiratory virus that usually causes mild, cold-like symptoms, although older adults are at greater risk for severe disease. It is spread through respiratory droplets, direct contact, and fomites. Learn more about RSV. 

There have been changes in the seasonality of RSV transmission following the introduction of SARS CoV-2 (see graph). There was a significant peak in RSV earlier in the season last year and in the year prior there were higher case numbers in the summer months. 

Clinical Presentation in Adults 

Typically, RSV causes mild or no symptoms including a runny nose, sore throat, cough, headache, fatigue, and fever. Older adults are at increased risk for becoming seriously ill, including lower respiratory tract infections and exacerbation of existing conditions. Learn more. 

People with chronic underlying medical conditions are associated with an increased risk of severe RSV disease, including those with: 

• lung disease 
• cardiovascular disease 
• moderate or severe compromised immune systems 
• diabetes mellitus 
• neurologic or neuromuscular conditions 
• kidney disorders 
• liver disorders 
• hematologic disorders 

Other factors associated with an increased risk of severe RSV disease include residence in a nursing home or other long-term care facility, advanced age, and frailty (although definitions vary, frailty can be defined as three or more of the following: unintentional weight loss, self-reported exhaustion, weakness, slow walking speed, or low physical activity). 

RSV Vaccines for Older Adults 

In May 2023, the Food and Drug Administration approved the first RSV vaccine. The Advisory Committee on Immunization Practices (ACIP) and the CDC recommend the RSV vaccine under shared clinical decision-making for adults 60 years and older. Under shared clinical decision-making there is no default decision to vaccinate, and health care providers should make recommendations to their patients on an individual basis, factoring in available evidence of the vaccine’s efficacy, the patient’s risk for disease, clinical discretion, and other factors. Learn more about shared clinical decision-making. 

The RSV vaccine can be coadministered with all other adult vaccines. There is no required interval between vaccines if they aren’t administered on the same day. The most important thing is that patients receive all their recommended vaccines in a timely way to help protect them against these major respiratory diseases this fall and winter virus season. 

There is currently limited data available on the immunogenicity of coadministration of RSV vaccines and other vaccines. In general, the coadministration of RSV and seasonal influenza vaccines met non-inferiority criteria for immunogenicity. However, RSV and influenza antibody titers were generally somewhat lower with coadministration, but the clinical significance of this is unknown. Additional studies on this and on immunogenicity of coadministration of RSV with other adult vaccines are in progress. 

Learn more about the RSV vaccine: 

RSV Vaccination: What Older Adults 60 Years of Age and Over Should Know 

Frequently Asked Questions About RSV Vaccine for Adults 

Healthcare Providers: RSV Vaccination for Adults 60 Years of Age and Over 

Influenza Activity and Clinical Care Guidance 

Recent Influenza Activity 

Influenza activity in the U.S. is currently low compared to last year when it peaked early. Last year was predominated by influenza A(H3N2) viruses and typically those kinds of seasons are more severe than seasons dominated by other influenza viruses. Predictions for the current season can be drawn from activity in the Southern Hemisphere, where influenza A(H1N1)pdm09 has been the dominant virus circulating. This suggests the influenza season in the U.S. might be dominated by the A(H1N1)pdm09 virus. 

Between 2010-2020, an estimated 9 million to 41 million illnesses, 140,000 to 710,000 hospitalizations, and 12,000 to 52,000 deaths associated with seasonal influenza epidemics occurred each year in the U.S. Although seasonal influenza activity was low during 2021-2022, preliminary estimates suggest that during the 2022-2023 season, 290,000 to 670,000 hospitalizations and 17,000 to 98,000 deaths were associated with influenza. 

Vaccination Recommendations 

There are many influenza vaccines available, and annual influenza vaccination is recommended for everyone six months and older. All influenza vaccines are quadrivalent–they are designed to protect against four different influenza viruses, including two influenza A viruses and two influenza B viruses. Health care providers should encourage patients to get an influenza vaccine now, or as long as influenza viruses are circulating in the community. 

The Advisory Committee on Immunization Practices (ACIP), an advisory group to the CDC, recommends that individuals 65 years of age and older receive a high-dose, recombinant, or adjuvanted vaccine; however, if those aren’t available a standard dose of an inactivated vaccine is better than no vaccine.  

Additionally, individuals six months of age and older with egg allergies should be vaccinated in accordance with typical safety measures that recommend that “all vaccines should be administered in settings in which personnel and equipment needed for rapid recognition and treatment of acute hypersensitivity reactions are available.” However previous severe allergic reaction to egg-based vaccines (inactivated or LAIV), cell culture vaccine, or recombinant vaccine is a contraindication to that specific vaccine. 

Coadministration of vaccines is considered best practice, and coadministration of influenza and COVID-19 vaccines is recommended. 

Preliminary data from a study of influenza vaccine effectiveness in five countries in South America in 2023 showed that vaccination was 70% effective among young children and 37% effective among older adults against hospitalization for severe acute respiratory infection with influenza viruses. 

Clinical Characteristics of Influenza 

There is a lot of overlap of signs and symptoms between uncomplicated influenza, COVID-19, and RSV, and other respiratory viral infections. Therefore, influenza testing can help to inform clinical management of patients with suspected influenza.  

Influenza complications may include: 

Moderate Illness: 

• Otitis media in young children, sinusitis 
• Exacerbation of chronic disease 

Severe to Critical Illness: 

• Exacerbation of chronic disease 
• Respiratory, i.e., viral pneumonia, croup, status asthmaticus, bronchiolitis, tracheitis, ARDS  
• Cardiac, i.e., myocarditis, pericarditis, myocardial infarction  
• Neurologic, i.e., encephalopathy & encephalitis, cerebrovascular accident, Guillain-Barre syndrome (GBS), Acute Disseminated Encephalomyelitis (ADEM), Reye syndrome 
• Bacterial co-infection, i.e., invasive bacterial infection (pneumonia), Staphylococcus aureus (MSSA, MRSA), Streptococcus pneumoniae, Group A Strept  
• Musculoskeletal, i.e., myositis, rhabdomyolysis 
• Multi-organ failure (respiratory, renal failure, septic shock) 
• Health care-acquired infections, i.e., bacterial or fungal ventilator-associated pneumonia) 

Learn more about influenza complications and illness.  

Groups at increased risk for influenza complications and severe disease: 

• Children under 2 years and adults aged 65 years and older 
• People with chronic medical conditions 
• People who are immunocompromised 
• People with extreme obesity 
• Children and adolescents who are receiving aspirin- or salicylate-containing medications 
• Residents of nursing homes and other long term care facilities 
• Pregnant people and people up to two weeks postpartum 
• People from certain racial and ethnic minority groups, including non-Hispanic Black, Hispanic or Latino, and American Indian or Alaska Native people 

Testing for Influenza 

There are a variety of influenza tests available in clinical settings for respiratory tract specimens, which differ by the time required to yield results, the viruses they target, and sensitivity.  

The Infectious Diseases Society of America (IDSA) recommends the following influenza tests: 

• For outpatients: rapid influenza molecular assays over recommended over rapid influenza antigen tests.  
• For hospitalized patients: RT-PCR or other influenza molecular assays are recommended. Rapid antigen detection tests and immunofluorescence assays are not recommended and should not be used unless molecular assays are not available. For immunocompromised patients, multiplex RT-PCR assays targeting a panel of respiratory pathogens, including influenza viruses, are recommended. 

*Do not order viral culture for initial or primary diagnosis of influenza: it takes too long and won’t yield timely results to inform clinical management 

*Do not order serology for influenza: results from a single serum specimen cannot interpret influenza antibody results, the testing must be done at a public health lab or specialized laboratory, and it is not useful for the clinical management of a patient. 

Learn more about the IDSA guidelines. 

Antivirals for Treatment of Influenza 

There are four FDA-approved antivirals recommended. All have demonstrated efficacy and are FDA-approved for early treatment within 48 hours of illness onset in outpatients with uncomplicated influenza. Learn more. 

Antiviral treatment is recommended and has the greatest clinical benefit when started as soon as possible for patients with confirmed or suspected influenza who are: 

• Hospitalized: oral/enteric oseltamivir, without waiting for test results 
• Outpatients with complicated or progressive illness of any duration: oral oseltamivir 
• Outpatients at high risk for influenza complications: oral oseltamivir or oral baloxavir 

Antiviral treatment can be considered for any previously healthy, non-high-risk outpatient with confirmed or suspected influenza (e.g., with influenza-like illness) based on clinical judgment if treatment can be initiated within 48 hours of illness onset. 

Randomized clinical trials have shown that oseltamivir treatment has significant clinical benefit when started within 36-48 hours after illness onset versus a placebo: 

• Children: reduced illness duration by 18 hours overall and by 30 hours in children without asthma; reduced risk of otitis media by 34% (Efficacy and Safety of Oseltamivir in Children. Read the abstract on PubMed.) 
• Adults: reduced illness duration by 25.2 hours; reduced risk of lower respiratory tract complications occurring more than 48 hours after treatment requiring antibiotics by 44% (Oseltamivir treatment for influenza in adults. Read the abstract on PubMed.) 

Clinical Management for Influenza in Hospitalized Patients 

• Implement infection prevention and control measures, including standard and droplet precautions. See the CDC guidelines for health care settings. 
• Start antiviral treatment as soon as possible. 
• Provide supportive care for complications: 
  • Secondary bacterial co-infections 
  • Respiratory failure, acute respiratory distress syndrome (ADRS) 
  • Sepsis 
  • Multi-organ failure (respiratory and renal) 

There is a gap in therapeutic management for severe influenza. However, there are some adaptive clinical trial platforms in progress that should yield data in a few years. Learn more about the REMAP-CAP adaptive trial. Learn more about the RECOVERY trial. 

RSV and Viral Bronchiolitis in Children 

Extensive research shows that steroids, beta-agonists, and nebulizers have no efficacy for the majority of children diagnosed with viral bronchiolitis and can have harmful side effects. This disease can be caused by any respiratory viral illness including RSV. Instead, respiratory illness in children should be managed with supportive care. Learn more. 

RSV and Pregnancy 

The American College of Obstetricians and Gynecologists (ACOG) recommends pregnant people receive the RSV vaccine between 32 and 36 weeks as part of routine vaccination during pregnancy, including those for influenza, Tdap, and COVID-19 to decrease the risk of severe disease. Clinicians should have thorough discussions throughout the course of a patient’s pregnancy to provide vaccine education and address their concerns.

Listen to the podcast, download the presentation slides, and access additional resources. 

What is the SCDP Project ECHO Program? 

Hosted by the Emory University Serious Communicable Diseases Program (SCDP), the SCDP Project ECHO Program is a forum for medical professionals responding to special pathogens to learn from infectious disease experts, ask questions, and share evolving best practices around special pathogen management. 

Emory University is one of 13 Regional Emerging Special Pathogen Treatment Centers (RESPTCs) funded by the U.S. Department of Health and Human Services Office of the Administration for Strategic Preparedness and Response (ASPR) to advance special pathogen preparedness. As the Region 4 RESPTC, the SCDP is responsible for preparing the region for special pathogen outbreaks. It does this through outreach and support programming, including in-person training, education via webinars and situation reports, and serving as subject matter experts for their region’s hospitals and EMS agencies, as well as for NETEC.