Neumonías Virales

Viral Pneumonias

The objective of this blog is to help the general population learn about various diseases related to Pulmonology. In such a way that anyone who suffers from a respiratory disease can know it better or can be able to promptly identify any symptoms that require medical evaluation and that this allows them to make broadly informed decisions with their doctor.

Today we will talk about generalities of viral pneumonia focused on influenza and covid, its clinical picture and outpatient treatments recommended as of the date of this publication.

At the end of the post you can leave us your comments and questions, or if you wish directly to our email:


Let's define pneumonia

Pneumonia is defined as an infection in the lung parenchyma, therefore an imaging study (ultrasound, x-ray or chest tomography) is required for its diagnosis. These infections are divided into categories depending on where they originated: Community Acquired Pneumonia (CAP) or Hospital Acquired Pneumonia (HAP). They can be caused by viruses, bacteria and even fungi.
Bacterial pneumonias are the main cause of pneumonia. In fact, a bacteria called Streptococcus pneumoniae has been the main causative microorganism of them. However, there have been virus pandemics: the penultimate one in 2009 caused by the H1N1 influenza virus and in 2019 by SARS-COV2.

Clinical picture

In general, we can mention that the symptoms of pneumonia are typically composed of cough, sputum (phlegm), fever and sometimes shortness of breath. However, presentations can be “atypical”, that is, due to different symptoms, such as general malaise, headache, dry cough, fatigue, anosmia (loss of smell), diarrhea, joint pain, among many others. Bacterial pneumonias are capable of giving typical and atypical symptoms; while viruses are considered “pneumonitis” causing atypical pneumonia.
Prior to the emergence of COVID-19, the influenza virus was the virus that most frequently caused pneumonia (50% of viral pneumonias) whose predominant symptoms are:
  • Dry cough,
  • pharyngeal pain,
  • Headache (headache),
  • Myalgia (muscle pain) and
  • Intense general malaise

On the other hand, Respiratory Syncytial Virus (RSV) is the most common in children and the second most common in elderly people.

Its main symptoms are:

  • Fever
  • Dry cough,
  • Otalgia (Earache),
  • Anorexia (Loss of appetite) and
  • Dyspnea (shortness of breath)

In the case of COVID19, it has been characterized by a constellation of signs and symptoms such as: headache, cough, anosmia (loss of smell), diarrhea, insomnia and anxiety among many others that involve the following systems:

  • Respiratory
  • Cardiovascular
  • Gastrointestinal
  • Musculoskeletal
  • Neuro-psychiatric
  • Endocrine.
Regardless of the cause of pneumonia, it can be mild, moderate or severe. That is to say; Although it will not necessarily cause respiratory failure and therefore can be managed at home; On some occasions it can progress to more severe forms of presentation where there may be respiratory difficulty or the recently described “happy hypoxemia” referring to the drop in oxygenation but without the patient's perception of it. Invariably, in cases of respiratory distress or decreased oxygenation (SpO2 < 92%), management within a hospital is suggested.


The routes of transmission vary by the type of organism, although it is generally through the air when in contact at less than 1.5 m for more than 15 minutes with an infected person. Likewise, there is also contagion through skin contact or contaminated articles that we call fomites. Once these germs reach the nasal mucosa or conjunctiva, they are capable of reproducing and infecting lung cells.


Our body has defenses that will protect us:
  • Mechanical barriers.
  • Immune system

The mechanical barriers are:

  • Fimbriae in our nasal passages that manage to stop large particles (10 microns);
  • Mucociliary clearance consisting of villi on the mucosa of the airways that help expel medium particles (5-10 microns).

In the immune system we can divide it in a very general way:

  • Humoral. It refers to immunoglobulins, mainly A, M and G.
  • Phagocytic cells. It refers to cells known as polymorphonuclear cells (PMN), macrophages and dendritic cells. These cells are the first defense when a virus enters the person's cells.
  • Cellular immunity. They are the main defense mechanism. They are involved in the production of antibodies and molecules called cytokines.


The diagnosis of pneumonia is generally made through a chest x-ray, although sometimes a chest tomography and/or lung ultrasound is necessary.

Although it is true that the distribution and type of image that we observe can guide us about the microorganism, it is advisable to perform studies to try to identify the cause of the pneumonia.

In the case of bacterial pneumonia, sputum (phlegm) cultures are performed, which is only recommended when the severity is sufficient to warrant hospitalization.

In the case of viral pneumonia, PCR by nasopharyngeal swab (PCR-HNF) is recommended, which can identify the SARS-COV2 virus, Influenza A, B and H1N1, as well as RSV.

Occasionally, two viruses can be found simultaneously and even a bacteria or fungus can complicate viral pneumonia, so the positivity of a study does not rule out the rest of the etiologies.


Antibiotics are recommended when the pneumonia is suspected to be bacterial, and are unnecessary in the case of viral pneumonia.

Antiviral treatment for pneumonia is as follows:


You can use: Oseltamivir, zanamivir, peramivir and baloxavir.
  • These are recommended in the first 48 hours of the onset of symptoms,
  • When symptoms worsen,
  • In all cases that require hospitalization,
  • In pregnant women
  • In all children under 2 years of age or ≥ 65 years of age
  • In all with chronic diseases such as asthma, hypertension, kidney, liver, among others.


It will depend on the severity of the disease.

In outpatient cases, without hypoxemia, the following can be used:

  • Paxlovid . It should be started within the first 5 days of the onset of symptoms, and is authorized in people ≥ 12 years of age. Reduces hospitalization and mortality from covid by 88%.
  • Remdesivir . It should be started within the first 7 days of the onset of symptoms, and is authorized in people ≥ 12 years of age. Reduces hospitalization and mortality by 87%.
  • Molnupiravir . It should be started within the first 5 days of the onset of symptoms, and is authorized in people ≥ 18 years of age. Reduces the risk of hospitalization and mortality by 30%.
  • Strongly avoiding using
  • Dexamethasone
  • Anticoagulants
  • Colchicine
  • Ivermectin
  • Chlorine dioxide

I am Dr. Cecilio Omar Ceballos Zúñiga, specialist in pulmonology and internal medicine [National Institute of Respiratory Diseases (UNAM) and General Hospital of the State of Sonora (UNAM)] and basic training at the Mexicali School of Medicine (UABC) . Co-founder of Breathbaja.

Ced. Prof. 4829126, reg. esp. 6119468 / 7440242

We are members of:
  • American Academy of Sleep Medicine
  • Mexican Academy of Sleep Medicine
  • Mexican Society of Pulmonology and Thorax Surgery
  • European Respiratory Society
  • American Thoracic Society
  • Latin American Thorax Association
  • Latin American Society of Respiratory Physiology
  • Mexican Society of Internal Medicine. Mexicali Chapter

Back to blog