How Contagious Is Respiratory Syncytial Virus?

Overview

Respiratory syncytial virus (RSV) is extremely infectious, especially during the 3-7-day period when an individual is symptomatic. Some infants and people with compromised immune systems may be infectious for up to four weeks. The virus is easily spread with droplets from an infected individual who sneezes or coughs. These droplets enter another person’s body through the mouth, nose or eyes. It can also be spread by touching surfaces where these viruses have fallen and then touching the face. This virus can survive on surfaces for several hours.

The symptoms usually appear two to eight days after being infected with RSV and typically persist for three to seven days. The majority of adults and children recover completely within one to two weeks.

What is RSV?

RSV is a microorganism causing respiratory diseases that affect people of all ages. In fact, RSV is the most prevalent cause of respiratory illness in newborns, and reinfection is common later in life. During the winter months, infection rates are often greater, resulting in bronchiolitis in newborns, common colds in adults, and more serious respiratory infections such as pneumonia in the elderly and immunocompromised people. Approximately 87% of newborns will have had an RSV infection by the age of 18 months, and nearly all children will have been infected by age three.¹ 

Causes and Risk factors

RSV affects all populations, ranging from newborns to the elderly. The risk factors of RSV vary, depending on the population^2-4:

Among infants and children 

• Low birth weight (< 2.5Kg)
• Lack of breastfeeding
• History of atopy (tendency to develop allergic symptoms)
• Household crowding with poor ventilation
• Congenital lungs or heart disease
• Maternal smoking during pregnancy or exposure to smoke as a newborn
• Prematurity (< 37 weeks of gestation) 

Among adults and elderly 

• Old age (>65 years)
• Chronic heart disease
• Chronic lung disease
• Living in close proximity to someone who is already infected with the virus (eg. residence homes)

Immunocompromised individuals

• Lymphopenia (a condition characterized by an unusually low amount of lymphocytes in the blood. Lymphocytes are white blood cells that play critical roles in the body's immune system)
• Neutropenia (a condition characterized by an unusually low neutrophil count in the blood. The bulk of circulating white blood cells are neutrophils, which act as the main defence against infections by eliminating bacteria and immunoglobulin-bound viruses in the bloodstream)
• Graft-versus-host disease (GvHD) (a condition characterized by inflammation in many organs and is often connected with bone marrow and stem cell transplantation)
• Long-term use of corticosteroids (this can lead to immunosuppression) 

Symptoms 

RSV infections result in a wide range of signs and symptoms, from mild to severe forms, which can be life-threatening, as it affects the respiratory system.  Symptoms also vary between children and adults.

Adults

RSV reinfection occurs frequently in adults. Adult re-infection is prevalent throughout life and results in mild to moderate symptoms that are identical to the common cold. Sometimes, they might be asymptomatic. However, when they have symptoms, it is usually restricted to the upper respiratory tract, such as runny nose, nasal congestion, sneezing, fever and fatigue. A lower proportion of adults could develop lower respiratory symptoms due to the progression of the disease to the lower respiratory tract.

Even though RSV infection seldom causes serious illness in otherwise healthy individuals, it can cause major morbidity and death in the elderly and those with underlying immune system impairment or cardiac disease.

Children 

Usually, RSV infections in children are self-limiting, with normal upper respiratory tract signs and symptoms such as:

• Nasal congestion
• Sneezing
• Runny nose
• Coughing
• Low-grade fever
• Sore throat, which may cause feeding difficulty
• Red eyes due to conjunctival infection

Children with the above-mentioned symptoms may also demonstrate signs of respiratory distress such as grunting, nasal flaring (the nostrils expand widely when breathing), intercostal retractions (when the muscles between the ribs draw inward) and subcostal retractions (when the abdomen pushes beneath the ribcage). The risk of illness progression is greater in children. Approximately 15% to 50% of children will develop severe lower respiratory tract infections, including bronchiolitis, viral pneumonia or croup. 

Transmission of RSV

How is RSV spread?

RSV is transmitted by contact with droplets from the infected individuals when they cough and sneeze. It can also be transmitted through dry respiratory secretions on surfaces such as bedsheets, doorknobs or counters, and other similar objects. It may survive on hard surfaces for several hours and on the skin for a much shorter period of time.

How contagious is RSV?

RSV is very contagious because it can be easily spread through contact with droplets during cough and sneeze (airborne).

Is there an incubation period?

The incubation period is the time between infection and the onset of symptoms. The incubation period of RSV ranges from 2-8 days, with an average period of 5 days.

How common is it?

RSV is very common, with most children experiencing an episode of the illness before age 2. Every year, around 20,000 infants are hospitalized due to RSV in England. Globally, the infection was seen in around 30 million people.

Is it a seasonal illness?

Yes, RSV is a seasonal illness, and it varies across the globe. Infection rates are higher in temperate areas during the winter months. This is frequently related to greater indoor congestion and viral stability in colder temperatures. However, in tropical and polar climes, yearly fluctuation is less well-defined and appears to be more prominent during the rainy season.⁶ 

Diagnosing RSV

By the signs and symptoms of the illness and the seasonality in which it occurs, the condition is easily diagnosed. The doctor will use a stethoscope to listen for any abnormal sounds when you breathe and evaluate the severity of your disease. The diagnosis will be based on the results of a physical examination and the time of year the symptoms occur.

Laboratory and imaging testing are rarely required. They can, however, aid in the diagnosis of RSV complications and rule out other illnesses that may cause similar symptoms. These tests include blood tests and chest X-rays.

Treatment 

In most cases, RSV infection is managed through supportive care, except in severe cases where medical intervention is needed.

Supportive Care

Medications are administered to alleviate the symptoms which include:

• Acetaminophen (Tylenol) to reduce fever. Children should never be given aspirin.
• Suctioning and nasal saline drops may help clear a stuffy nose.
• Drink plenty of water to prevent dehydration. 

Hospital care

In severe cases, medical-guided or hospital care such as humidified oxygen, IV fluids and mechanical ventilation may be needed. Drugs such as bronchodilators and steroids do not improve the condition, so are not administered except if the infection triggers asthma attacks in patients with asthma.

Prevention

Steps required to prevent the spread of RSV infection include:

• Sneeze and cough with a tissue to prevent the spread of droplets. The upper sleeve of your shirt may also be used instead of your hand.
• Avoid close contact with people, especially children.
• Wash your hands often with soap and water, or clean using sanitiser when you touch surfaces in public spaces.
• Disinfect surfaces where there is constant contact in the house or workspace.

Summary

RSV is a common respiratory virus that causes cold-like symptoms. Most people recover in a week or two, but RSV can develop into a severe illness, especially in newborns, immunocompromised people and the elderly. The virus spreads quickly by droplets from infected persons, especially during the winter. The majority of symptomatic persons have mild symptoms that are managed with supportive treatment.