RSV Alert: Latest Prevention Options Every Parent Should Know

For parents of young infants, hearing your baby’s severe cough or wheezing can be deeply distressing. Aside from flu, RSV (Respiratory Syncytial Virus) is a major cause of concern during autumn, winter, and early spring. RSV is one of the leading causes of serious respiratory infections in young children and a common reason for hospitalisation in infants under one year old. This article will provide an in-depth look at RSV symptoms, progression, the latest prevention measures, and home care recommendations. 

What is Respiratory Syncytial Virus (RSV)?       

RSV, or Respiratory Syncytial Virus, is a highly common virus. In Hong Kong, RSV infections can occur year-round, but parents should stay particularly alert during the virus’s peak transmission period, typically from late February to late September.

RSV spreads through several routes, including direct contact with an infected person’s secretions, as well as droplets released when someone coughs or sneezes. It can also be transmitted indirectly through contact with contaminated objects or surfaces. Everyday activities—like playing in parks, attending nurseries, or visiting relatives—can expose infants and children to the virus. 

Is It Common for Babies to Contract RSV? 

Studies show that nearly 90% of infants will have contracted RSV by the time they turn two, with reinfections also being possible. 

While RSV typically causes mild, cold-like symptoms in older children and adults, it can pose a much greater risk to infants under one year old, particularly those aged six months or younger or born prematurely. In these cases, the virus can spread to the lungs, causing more severe illnesses such as bronchiolitis or pneumonia. These conditions may require hospitalisation, mechanical ventilation, or, in severe cases, could be fatal. Alarmingly, over 70% of RSV-related hospitalisations involve healthy, full-term infants. 

Recognising RSV Symptoms 

Initially, RSV symptoms resemble those of a common cold but can rapidly worsen, particularly in young infants. Parents should watch for the following signs: 

Early Symptoms 

• Runny or stuffy nose

• Low-grade fever

• Coughing

• Sneezing 
  

Additional Symptoms in Babies Under Six Months 

• Rapid breathing
• Irritability or restlessness
• Reduced activity levels
• Decreased appetite
• Apnea (lasting more than 10 seconds)
• Lethargy 

Signs of Worsening Condition 

• Difficulty breathing
• Wheezing
• Severe and persistent cough
• High fever
• Cyanosis (bluish discoloration of the skin due to lack of oxygen) 

Note: If your baby shows any severe symptoms, such as rapid breathing, chest retractions, flaring nostrils, persistent high fever, signs of severe exhaustion or lethargy, seizures or poor oral intake—please seek medical attention immediately. 

How to Effectively Prevent RSV? 

RSV is one of the main causes of hospitalisation in infants, making it a significant concern, especially for newborns. Thanks to advancements in medical science, there are now three key preventative measures available: 

1.  Beyfortus (Long-acting Monoclonal Antibody Injection) 

• Who is it for? Newborns and infants under two years old.
• How it works: Provides passive immunity by directly delivering antibodies for immediate protection, without relying on the baby’s immune system.
• Effectiveness: A Clinical study shows Beyfortus reduces the risk of hospitalisation due to RSV-related lower respiratory tract infections by 26%, compared to maternal RSV vaccination. A single injection provides protection for up to five months. 

2. ABRYSVO (RSV Vaccine) 

• Who is it for? Pregnant women (between 32 and 36 weeks of pregnancy).
• How it works: Antibodies are passed from the vaccinated mother to the baby via the placenta, offering protection after birth.
• Effectiveness: Reduces the risk of severe RSV-related lower respiratory tract infections by 76.5% during the baby’s first six months. 

 3. SYNAGIS (Short-acting Monoclonal Antibody Injection) 

• Who is it for? Premature infants born before 29 weeks of gestation, or children under one year with congenital heart disease or bronchopulmonary dysplasia (BPD).
• How it works: Like Beyfortus, it provides passive immunity.
• Effectiveness: Reduces hospitalisation risks by 55% for premature or BPD infants. Monthly doses are required for continued protection. 

Parents are advised to consult a paediatrician to determine the most appropriate prevention option based on their baby’s health condition.

What If Your Baby Contracts RSV? Home Care Tips

At present, there is no specific antiviral medication for RSV. Treatment focuses on relieving symptoms and making the patient comfortable. It is completely understandable for parents to feel worried when their baby is infected with RSV. However, most RSV infections are resolved on their own within one to two weeks, so it is important for parents to stay calm and focus on caring for their baby during this period.

Below are the home care recommendations for parents, provided by the Hong Kong Society of Paediatric Immunology, Allergy and Infectious Diseases together with various paediatric societies and healthcare associations: 

1. Keep Track of Symptoms: Record key details such as when symptoms started and their progression to allow assessment of the condition.  
2. Monitor Regularly: Observe oral fluid, food intake and the frequency of urination and bowel movement, and watch for any new or worsening symptoms.
3. Measure and Record Temperature: Use an ear thermometer to check your baby’s temperature every four hours. 

Strengthening Your Baby’s Defence Against RSV 

References

1. Chan, P.K.S., et al., (2015) Hospitalization Incidence, Mortality, and Seasonality of Common Respiratory Viruses Over a Period of 15 Years in a Developed Subtropical City. Medicine, [online] 94(46), p.e2024. doi:https://doi.org/10.1097/MD.0000000000002024.
2. ‌Lee Mortensen, G. and Harrod-Lui, K, (2022) Parental knowledge about respiratory syncytial virus (RSV) and attitudes to infant immunization with monoclonal antibodies. Expert Review of Vaccines, 21(10), pp.1523–1531. doi:https://doi.org/10.1080/14760584.2022.2108799. 
3. Centre for Health Protection, (2025) Respiratory Syncytial Virus Infection. Retrieved 4 February 2026 from https://www.chp.gov.hk/en/healthtopics/content/24/36.html
4. 香港兒童免疫過敏及傳染病學會, 聯合聲明：照護嬰幼兒及高危人群的呼吸道合胞病毒（RSV）感染及其預防. Retrieved 4 February 2026 from https://www.hkspiaid.org/download/20251120%20Caring%20for%20Respiratory%20Syncytial%20Virus%20extension%20to%20adults%20protection/%E7%85%A7%E8%AD%B7%E5%AC%B0%E5%B9%BC%E5%85%92%E5%8F%8A%E9%AB%98%E5%8D%B1%E4%BA%BA%E7%BE%A4%E7%9A%84%E5%91%BC%E5%90%B8%E9%81%93%E5%90%88%E8%83%9E%E7%97%85%E6%AF%92%EF%BC%88RSV%EF%BC%89%E6%84%9F%E6%9F%93%E5%8F%8A%E5%85%B6%E9%A0%90%E9%98%B2__20112025_TC.pdf
5.  BEYFORTUS Prescribing Information. Retrieved 4 February 2026 from https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/761328s000lbl.pdf
6. Jabagi, M.-J., et al, (2025) Nirsevimab vs RSVpreF Vaccine for Respiratory Syncytial Virus-Related Hospitalization in Newborns. JAMA, [online] p.e2524082. doi:https://doi.org/10.1001/jama.2025.24082.
7. ABRYSVO Prescribing Information. Retrieved 4 February 2026 from https://www.fda.gov/media/168889/download?attachment
8. The IMpact-RSV Study Group, (1998) Palivizumab, a Humanized Respiratory Syncytial Virus Monoclonal Antibody, Reduces Hospitalization From Respiratory Syncytial Virus Infection in High-risk Infants. PEDIATRICS, 102(3), pp.531–537. doi:https://doi.org/10.1542/peds.102.3.531.