Respiratory viruses: the most frequent types, evolution and prevention

With the arrival of the cold weather, respiratory viruses take on significance again. The drop in temperatures, spending more time in closed spaces or the changes in humidity encourage, amongst other factors, the transmission of pathogens such as flu (influenza), COVID-19 (SARS-CoV-2) or the respiratory syncytial virus (RSV).

During the pandemic, sources from the Infectious Diseases Unit of the Internal Medicine Service at the Hospital de Barcelona explain, “the circulation of ´flu, RSV, parainfluenza and metapneumovirus dropped, while other viruses such as rhinovirus/enterovirus and the seasonal coronaviruses remained stable.” After lifting the restrictions, the viruses reappeared in a staggered way and today, the activity and seasonality of respiratory viruses are returning to pre-pandemic patterns.

In adults and the elderly, the most important viruses, according to the Infectious Diseases Unit, are ´flu, RSV, rhinovirus, seasonal coronavirus and metapneumovirus. In these groups, the infection can become serious due to the presence of other diseases and due to the actual ageing of the immune system. Co-infections are less frequent in children, “but they increase in the elderly who live in residential centres,” they state.

In the case of children under the age of two years, bronchitis continues to be, year after year, one of the respiratory diseases with the greatest impact. This pulmonary infection inflames and congests the bronchioles and is usually caused by respiratory syncytial virus (RSV). It starts out as a cold with a cough, phlegm and at times, a low-grade fever, which rarely exceeds 38,5 °C, but that can derive towards respiratory difficulty which can require hospital valuation.

The most common respiratory infections

The most frequent respiratory viruses are rhinovirus/enterovirus, respiratory syncytial virus (RSV), influenza A, seasonal coronavirus, adenovirus, parainfluenza and metapneumovirus. They are usually short processes, with a viral origin and that rarely present any complications. 

However, there are symptoms that should make patients consult their doctor, such as “breathlessness, chest pain, an alteration in the mental state such as confusion, a stiff neck, persistent fever or low blood pressure,” according to sources from the Infectious Diseases Unit of the Internal Medicine Service at the Hospital de Barcelona. 

They also recall that this is a symptomatology that must be looked at carefully in cases of  vulnerable people, (patients over the age of 65 years, immunocompromised patients, pregnant women, chronic patients or nursing infants.) The experts estimate that the “advances in broad spectrum antivirals, latest generation vaccines and monoclonal antibodies” will be essential in a future when managing all these viruses.  

1. The common cold. It represents around 80% of acute respiratory infections. It is usually caused by rhinoviruses, although there are over 200 viruses involved, such as seasonal coronavirus, adenovirus, enterovirus and parainfluenza. After two or three days of incubation, nasal congestion, sneezes, sore throat and a slight cough appear. A temperature is not frequent in adults. The symptoms usually get better in less than ten days.
2. ´Flu (influenza). The influenza A and B viruses cause seasonal epidemics every winter. Unlike the cold, ´flu starts suddenly, with a high temperature, muscle pain, headache and a general feeling of being ill. Although it usually disappears within a week, it might cause respiratory complications, particularly pneumonia, in older people, chronic patients, pregnant women and children.  
3. COVID-19. SARS-CoV-2 continues to form part of the epidemiological panorama. Its symptoms may overlap with those of ´flu, although it more frequent for it to cause nasal congestion, a sore through and the loss of the sense of smell or taste. It lasts for a variable length of time: from 5 to 14 days in most cases.
4. Respiratory Syncytial Virus (RSV). In adult patients, this virus usually appears as a slight cold but in nursing infants and people over the age of 65 years, it can derive into bronchiolitis or pneumonia. The incidence of RSV usually increases slightly before ´flu, with peaks in December and January. 

How to reduce the contagion?

La combinación del cambio climático, el aumento de la población, el contacto humano-animal o el incremento de viajes internacionales y personas vulnerables desde un punto de vista sanitario está favoreciendo patrones más erráticos de transmisión de virus respiratorios. Desde el Hospital de Barcelona aportan algunas medidas que pueden prepararnos para el futuro: para los especialistas es clave, por ejemplo, “reforzar la vigilancia epidemiológica a escala ambiental y de centros sanitarios de forma integrada, además de fortalecer el sistema de atención primaria y los planes de contingencia en los aumentos bruscos de casos”. Además, coinciden en que la prevención es la herramienta más eficaz para frenar la transmisión de virus respiratorios. Entre las recomendaciones destacan:

The combination of climate change, increase in the population, human-animal contact or the increase in international travel and vulnerable people from a healthcare point of view is encouraging more erratic transmission patterns of respiratory viruses. Sources at the Hospital de Barcelona inform of some steps that can prepare us for the future: for the specialists it is essential, for example, “to strengthen the epidemiological monitoring on an environmental scale and in healthcare centres in a comprehensive way, in addition to strengthening the primary care system and the contingency plans for the sudden increase in cases.” They also coincide in the fact that prevention is the most effective tool for curbing the transmission of respiratory viruses. Amongst the recommendations the following stand out: 
 

• Cover your face when coughing or sneezing.
• Ventilate interior spaces.
• Disinfect surfaces. 
• Avoid tobacco and smoky environments.
• Follow a healthy lifestyle and eat a good diet.
• Use face masks in closed spaces when you are ill or if you live with vulnerable people.
• Carry out the annual vaccination against ´flu and COVID-19, particularly for people over the age of 60 years, pregnant women, immunocompromised people and small children according to healthcare criteria.