WHAT IS RSV INFECTION?

• One of the most prevalent causes of illness in children, respiratory syncytial virus (RSV) was discovered in 1956, since then it has caused morbidity in both infants and old age.

• In the US (United States) every year RSV leads to about,

  • 2.1 million outpatient visits among children younger than 5 years old and 100–300 deaths among them.

  • 60,000-160,000 hospitalizations among 65 years and older. Among them, 6,000-10,000 deaths are reported. (1)

• Common cold-like symptoms are often the result of RSV belonging to Orthopneumovirus having 2 subtypes- A and B.

• Transmission begins in the fall and peaks in winter. But COVID-19 has disrupted the seasonal consistency in circulation patterns. (1)

• In infants younger than a year old in the US, RSV is the leading cause of bronchiolitis and pneumonia.

• In adults, it can be fatal in some cases. Among them, those at higher risk for a life-threatening RSV infection are:

  
  

  1. Seniors, particularly those 65 years

  
  

  2. With compromised immune systems

  
  

  3. Those diagnosed with chronic heart or lung disease

• In the elderly, it can occasionally develop problems like Pneumonia, worsened symptoms of Asthma, Chronic Obstructive Pulmonary Disease (COPD), and Congestive Heart Failure(CHF).

• Those over 65 years who get RSV exposure may require hospitalization. There's a chance of mortality also. Because immune systems deteriorate with age, seniors are at a higher risk than young folks for catastrophic consequences from RSV.

WHAT IS THE MODE OF TRANSMISSION?

• Direct contact with respiratory droplets, indirect contact like touching a surface that has the virus on it, and touching your face without washing hands.

• Incubation period-: 2-8 days

• Infection does not give any immunity. (2)

DIAGNOSIS OF RSV INFECTION

• Clinical manifestations of RSV are not unique.

• Even though a number of diagnostic options are available which are not routinely done, clinicians mostly opt for clinical diagnosis.

  • More sensitive test like real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) is one of the investigations.

  
  

SURVEILLANCE SYSTEMS IN THE U.S.A.

• RSV Hospitalization Surveillance Network: Hospitalizations from RSV are tracked using a population-based surveillance system. (1)

• National Respiratory and Enteric Virus Surveillance System (NREVSS): lab-based surveillance system for tracking the spread of RSV and other viruses over time and space. (1)

• New Vaccine Surveillance Network: multisite, population-based surveillance network for hospitalizations and outpatient visits associated with RSV and other acute respiratory disorders. (1)

• The RSV Surveillance in Native American Persons (RSV SuNA): to track hospitalizations and outpatient visits associated with RSV among Native Americans. (1)

Vaccine developments started in 1960 onwards. But most of them didn’t succeed. (3) There is prophylaxis for infants at risk and young children but not for older age groups which emphasize the need for vaccines.

NEW VACCINE FOR RSV- AREXVY

• GlaxoSmithKline Biological’s Arexvy, the first vaccine against RSV, was approved by the U.S. FDA on May 3, 2023, for those aged ≥60, to protect themselves from RSV-related respiratory illness. US FDA is an agency within the U.S. Department of Health and Human Sciences assuring the safety and effectiveness of vaccines and drugs for use in humans. (4)

• It is a recombinant subunit prefusion RSV F glycoprotein antigen with adjuvant. Protective for both type A and B viruses. (5)

• Evidence for Arexvy's safety and efficacy comes from ongoing, randomized, placebo-controlled clinical research in people aged 60 and more than 60 years in the US and other countries.

• Arexvy's primary clinical research aimed to evaluate the efficacy and safety of a single dose in people aged 60 and up. In order to evaluate the same for repeated immunization, participants will remain in the trial for three RSV seasons.

• Comparing those who got Arexvy to those who received a placebo, vaccination dramatically reduced the risk of getting RSV-associated LRTD by 82.6% and decreased the chance of developing severe RSV-associated LRTD by 94.1%.

• Reported side effects by Arexvy recipients: injection site soreness, muscular pain, headache, and joint stiffness or pain. Few had atrial fibrillation. 

• FDA requires a post-marketing study to evaluate substantial risks for Guillain-Barré syndrome and ADEM (Acute Disseminated encephalomyelitis).

• Vaccines will be available for older individuals prior to the 2023/2024 RSV season, which typically begins in the fall.

• Route of administration: Intramuscular injection

• Dosage: 0.5ml. Reconstituted vaccine should be administered immediately or can be stored at 2- 8 degree Celsius at room temperature protected from light and used within 4 hours. If not used within 4 hours, the reconstituted vaccine must be discarded. (5)

• Contraindication: Anyone with a history of anaphylaxis to any vaccine component.

• The cost of the vaccine has not yet been decided.

• 30 European countries are also authorized for vaccine usage. (6)

Conclusion:

Now the recommendation should come from the Centres for Disease Control and Prevention (CDC) after reviewing by Advisory Committee on Immunization Practice (ACIP) on various aspects like epidemiology, immunogenicity, cost-effectiveness, and whether to give it for all ≥60 or those with comorbidities. But some problems like lack of awareness and vaccine hesitancy will be there. Vaccines for pregnant women are also in the trials. In India RSV is the most common cause of acute respiratory infection in young children and candidate vaccines are in the pipeline.

References:

1. CDC. respiratory syncytial virus(RSV).Available from: https://www.cdc.gov/rsv/index.html.

2. Guidelines on the quality, safety and efficacy of respiratory syncytial virus vaccines, Annex 2, TRS No 1024. Available from: https://www.who.int/publications/m/item/respiratory-syncytial-virus-vaccines-annex-2-trs-no-1024)

3. Respiratory Syncitial Virus (RSV) Disease. Available from: https://www.who.int/teams/health-product-policy-and-standards/standards-and-specifications/vaccine-standardization/respiratory-syncytial-virus-disease)

4. U.S. Food and Drug Administration.Press announcements. FDA Approves First Respiratory Syncytial Virus (RSV) Vaccine. Available from:https://www.fda.gov/news-events/press-nnouncements/fda-approves-first-respiratory-syncytial-virus-rsv-vaccine

5. GSK.Highlights of Prescribing Information.Available from : https://gskpro.com/content/dam/global/hcpportal/en_US/Prescribing_Information/Arexvy/pdf/AREXVY.PDF

6. GSK.Press releases. Available from : https://www.gsk.com/en-gb/media/press-releases/european-commission-authorises-gsk-s-arexvy-the-first-respiratory-syncytial-virus-rsv-vaccine-for-older-adults/