Children with severe respiratory infections are on the rise in UK hospitals. This includes an unseasonal rise in the respiratory syncytialvirus (RSV) infection in children as young at two months.This has led to an increase in hospital admissions for bronchiolitis (a form of bronchitis).RSV is considered a winter disease. Its peak in summer 2021.Simply put, other respiratory viruses were also prevented from spreading by COVID-19-restrictions. Many respiratory diseases are now spreading as many countries lift these restrictions.RSV is a common pathogen that affects the respiratory system. It's so widespread that almost all people are infected by it before they turn two. This virus causes mild symptoms that resemble a severe cold. It can cause a runny nose, cough, and runny eyes. These symptoms usually resolve within one to two weeks.RSV can lead to bronchiolitis in about one third of children. This is an inflammation of our smallest tubes, the bronchioles. Patients experience difficulty breathing and a reduced airway, which can cause a variety of symptoms, including a wheezing sound and increased temperatures.Bronchitis can be treated with fluids and paracetamol. However, it is possible to become a serious condition. When bronchiolitis becomes severe in young people, it can lead to breathing difficulties, blue lips, temperature over 38° Celsius, and difficulty breathing.Young children may refuse to eat or use dry nappies for prolonged periods of time. Many parents make the right decision to send their child to the hospital.Children as young as six months old are most at risk of being admitted to the hospital. This is due to their smaller airways.Bronchitis can sometimes be treated, but it is possible to die. Globally, 3.5 million children are admitted to hospital each year. Around 5 percent of these cases result in death.Delayed surgeIt appears that COVID responses such as increased hand washing, mask wear, and reducing contact between people have led to a significantly decreased flu season in winter 2020-21.Similar results were seen for RSV. Studies showed that bronchiolitis was associated with 84 percent less hospitalizations in the northern hemisphere than previous years. Australia also saw dramatic reductions in hospitalizations due to bronchiolitis.The opposite is now happening. This will affect a whole year's worth of newborns who didn't get any respiratory viruses during restrictions.It is not known why RSV-infected children experience mild symptoms while others become severely ill. There are many risk factors that can lead to severe RSV disease, such as age (one-month-olds are most at risk), gender (males are statistically at greater risk than women), environmental factors, like smoking, underlying lung diseases and other genetic factors.It is not yet possible to predict which children will get bronchiolitis despite this knowledge. These risk factors are known and prophylactic treatment is given to high-risk individuals in certain countries.A strong immune response is crucial to clearing an infection, as with all infectious agents. It is known that severe illnesses are protected by high levels of neutralizing antibodies, including maternal antibodies and anti-infective treatments like palivizumab.However, RSV immunity is not permanent or complete. Most people are re-infected every day. Despite the immense efforts of many research groups, no vaccines are currently available.Our immune system can also cause damage when trying to get rid of an infection. Certain immune responses associated with RSV have been shown to increase disease severity and are linked to the development asthma.Because of the prevalence of RSV and asthma in the UK both, the link between them is widely studied. I'm currently involved in the Wellcome Trust funded Breathing Together project.RSV vaccines and treatments must be balanced between being effective in clearing the infection and not causing any negative side effects. There have been many mistakes made, including failed attempts to develop an RSV vaccine in 1960. This led to children becoming very ill.Vaccines for RSV are still in development, but RSV immunity is now better understood and researched. Many are in clinical trials to ensure that all children are protected from RSV-induced Bronchitis.Grace C Roberts is a Research Fellow in Viology at Queen's University Belfast.This article was republished by The Conversation under Creative Commons. You can read the original article.