Could SARS-CoV-2 cause the deadliest form of pneumonia? In a breakthrough article recently published in the February 2022 issue of the International Journal of Infectious Diseases, a group of medical researchers from Spain shared their findings in which patients hospitalized for bacterial pneumococcal pneumonia (B-PCAP) were compared to those hospitalized for pneumonia from SARS-CoV-2 – the virus that causes COVID-19 infection[1].  

Pneumonia is brought on by a viral, bacterial, or fungal infection, during which the small air sacs in your lungs, also known as alveoli, are clogged with pus or fluid[2]. A typical patient with pneumonia likely will have a cough with mucus and other symptoms such as fever, chills, and trouble breathing. Globally, the majority of bacterial pneumonia cases are caused by a pathogen known as Streptococcus pneumoniae[3]. It also causes the most hospitalized and fatal cases of pneumonia around the world[4]. 

During the COVID-19 pandemic, cases of pneumonia caused by SARS-CoV-2 have surfaced. As of now, over 5 million people have died globally due to complications from COVID-19[5]. Few studies have compared SARS-CoV-2 pneumonia to other forms of pneumonia. The study from Spain spearheaded by Serrano et al. (2022) aims to compare B-PCAP, a prevalent variant ,to SARS-CoV-2 pneumonia to better understand disease caused by SARS-CoV-2.

The study collected samples and demographic information from patients who were admitted to hospitals in Spain between March and December 2020 for SARS-CoV-2 pneumonia, and compared it to data from patients hospitalized for B-PCAP between January 2000 and May 2020. Patients who were immunocompromised were not included in this study. SARS-CoV-2 infection was tested via the nasal swab PCR method, and infection from B-PCAP was measured through blood samples. Standard x-ray images were used to confirm lung infection in all patients. 

When comparing the two patient groups, B-PCAP seems to mainly target patients over 65 years of age and those with underlying conditions such as chronic obstructive pulmonary disease caused by heavy smoking and drinking. In contrast, SARS-CoV-2 pneumonia attacked adults of all ages and health backgrounds. These patients also exhibited less symptoms compared to those sick with B-PCAP. Those with B-PCAP exhibited more instances of mucus present in coughs and chest pain, among other classic signs of pneumonia. Yet, these symptoms only lasted for about 3 to 4 days. Those with SARS-CoV-2 mainly experienced high respiratory system inflammation. One possible reason for this was that patients afflicted with B-PCAP were more likely to show prior extreme symptoms than those with SARS-CoV-2 when admitted, which was when a lot of the characteristic data was collected. 

Despite B-PCAP presenting more clinical severity, it was the SARS-CoV-2 form of pneumonia that resulted in higher in-hospital mortality within the patient population. A possible theory is that with B-PCAP causing more visible symptoms, these patients are more aware of their ailments, prompting them to seek help quicker. There’s also the fact that the SARS-CoV-2 virus is more potent, triggering strong innate inflammatory reactions, like tightness in the chest and closing of the throat, which imposes more respiratory stress on the patient. It was also found that SARS-CoV-2 pneumonia patients were more likely to have both lungs affected, which could also intensify the respiratory stress.

It should also be considered that B-PCAP has been around for much longer than SARS-CoV-2. Vaccines to fight against B-PCAP have helped improve patient outcomes over the years[6], and the illness has been around long enough to improve early diagnosis and treatments[7]. At the time that the SARS-CoV-2 patients’ data was collected, the vaccine and other treatments were not available yet. Whether the current COVID-19 vaccines and treatments would help to lower the mortality rate is an important question for future studies.

By comparing characteristics between the most common form of pneumonia and this newer form, we can better pinpoint specific demographics of patients that may be more at risk for SARS-CoV-2 pneumonia. A better understanding of unique symptoms with this new variant may warrant and advocate for more serious medical attention. Through this study, we learn that unlike B-PCAP, SARS-CoV-2 pneumonia can target any adult, particularly in the elderly and in those with underlying medical conditions. The number of in-hospital deaths could potentially indicate that it’s more fatal than other forms of pneumonia. With the only distinct signs of SARS-CoV-2 pneumonia being acute inflammation and respiratory distress, this further supports that those infected with COVID-19 should seek medical attention if they are having trouble breathing and experiencing tightness in the chest. 

Reference 

1. Serrano Fernández, L., Ruiz Iturriaga, L. A., España Yandiola, P. P., Méndez Ocaña, R.,        Pérez Fernández, S., Tabernero Huget, E., Uranga Echeverria, A., Gonzalez Jimenez, P., García Hontoria, P., Torres Martí, A., Menendez Villanueva, R., & Zalacain Jorge, R. (2022). Bacteraemic pneumococcal pneumonia and SARS-COV-2 pneumonia: Differences and similarities. International Journal of Infectious Diseases, 115, 39–47. https://doi.org/10.1016/j.ijid.2021.11.023
2. U.S. Department of Health and Human Services. (n.d.). Pneumonia. National Heart Lung and Blood Institute. Retrieved January 29, 2022, from https://www.nhlbi.nih.gov/health/pneumonia
3. Mayo Foundation for Medical Education and Research. (2020, June 13). Pneumonia. Mayo Clinic. Retrieved January 29, 2022, from https://www.mayoclinic.org/diseases-conditions/pneumonia/symptoms-causes/syc-20354204
4. Johansson, N., Kalin, M., Tiveljung‐Lindell, A., Giske, C. G., & Hedlund, J. (2010). Etiology of community‐acquired pneumonia: Increased microbiological yield with new diagnostic methods. Clinical Infectious Diseases, 50(2), 202–209. https://doi.org/10.1086/648678
5. Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU). (2022). COVID-19 Dashboard. Coronavirus Resource Center – Johns Hopkins University & Medicine. Retrieved February 23, 2022, from https://coronavirus.jhu.edu/map.html
6. Centers for Disease Control and Prevention. (n.d.). Pneumococcal disease (streptococcus pneumoniae). Centers for Disease Control and Prevention. Retrieved January 28, 2022, from https://wwwnc.cdc.gov/travel/diseases/pneumococcal-disease-streptococcus-pneumoniae
7. Pneumonia. Johns Hopkins Medicine. (n.d.). Retrieved January 29, 2022, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/pneumonia