As winter sets in, the risk of respiratory illnesses rises sharply. Among these, the Respiratory Syncytial Virus (RSV) becomes more common—especially in young children. To understand why RSV cases rise in cold weather and how to identify early symptoms, AIIMS Delhi pediatric specialist Dr. Himanshu Bhadani explains the virus in detail.

What is RSV?
According to Dr. Himanshu, RSV is a highly contagious virus that infects the lungs and respiratory tract. It is so common that most children contract it before the age of two. While it can infect adults as well, the infection is typically more severe in:

• Infants below 12 months
• Premature babies
• Children with congenital heart or lung diseases
• People with weakened immune systems

Why do RSV cases rise in winter?
Dr. Himanshu explains that RSV circulates throughout the year but its incidence increases during the winter months. The reasons include:

• Low humidity: Cold, dry air helps the virus survive longer and spread more easily.
• Less sunlight/Vitamin D deficiency: Low vitamin D levels may weaken immunity, especially in children.
• Indoor crowding: People stay indoors during cold weather, increasing the chance of transmission.

How long does the infection last?
Most RSV infections are mild and clear up within:

• 3–7 days in typical cases
• Up to 2 weeks in stronger infections

But in some children—especially infants—RSV can turn serious and lead to complications such as bronchiolitis or pneumonia. Dr. Himanshu warns that rapid breathing, wheezing, or persistent cough require immediate hospital attention.

Early symptoms of RSV
Parents should watch for the following early signs:

• Feeling unusually cold or chilled
• Severe body aches
• Sore throat
• Runny or blocked nose
• Mild fever
• Rapid or difficult breathing
• Wheezing
• Persistent cough that worsens at night

These symptoms may resemble a common cold, which is why RSV often goes unnoticed in the beginning.

How to protect children from RSV