Study: Croup Associated With SARS-CoV-2: Pediatric Laryngotracheitis During the Omicron Surge. Image Credit: rumruay / Shutterstock

Evidence of diphtheria associated with SARS-CoV-2

Croup, inflammation of the mucous membrane of the upper airway under the glottis manifests as airflow obstruction for shortness of breath in children. In addition, it is associated with edema at the epithelium level, and most emergency department (ED) admissions are caused by acute viral infection.

Study: Diphtheria Associated with SARS-CoV-2: Pediatric Laryngitis and Laryngitis During Omicron Increase. Image Credit: rumruay / Shutterstock

The frequency of presentations appears to be variable based on local prevalence and specific viral pathogens. About 75% of cases are due to a specific parainfluenza virus (PIV), of the four subtypes, while the rest are caused by common seasonal respiratory viruses. Common cold viruses, in addition to endemic coronaviruses, are included in the standard multiplex RVP (Respiratory Viral Panel Test).

A small number of cases (<10) were reported from the SARS-CoV-2-associated cluster 2 (SARS-CoV-2) before the increase in cases associated with the Omicron variant. For these, the RVP multi-etiology test confirmed the etiology of SARS-CoV-2.

From December 2021 to January 2022, the metropolitan city of Atlanta experienced a sudden rise in the prevalence of coronavirus disease 2019 (COVID-19), which was evident by the sudden escalation in cases of diphtheria ED.

the study

A new study was published in Journal of the Society of Pediatric Infectious Diseases It aims to characterize the clinical features of the group associated with SARS-CoV-2 among children who progress to ED during the phase in which transmission of the Omicron variant was high.

Here, ED visits associated with SARS-CoV-2 infection were identified, and the frequency of diphtheria was compared between these pediatric patients during the study period and in the preceding delta phase.

Patterns of ED visits during both time periods were analyzed to determine whether the presentations could be attributed to SARS-CoV-2 strains. Cases are categorized into Period 1 – Omicron-dominant (between December 2021 to January 2022) and Period 2 – Delta-dominant (between July 2021 to August 2022).

Next, cases with a diagnosis of concurrent diphtheria were identified, and the frequency of this co-association between the two time periods was compared. The effect on younger children during the two outbreaks was differentiated by comparing the significance of relative differences.

the findings

Overall, 218,387 emergency department visits were recorded from 2021 to 2022; Of these, 15.9% were hospitalized. The Omicron period saw a tripling of ED group visits which coincided with a high prevalence of SARS-CoV-2. The acceptance rate during this phase was from 12.1% to 15.6%. While the general acceptance rate of diphtheria during this period ranged from 12.1% to 15.6%.

Interestingly, all other respiratory viral infections occurred less frequently during the Omicron period. However, during the delta period, respiratory syncytial virus (RSV) and rhino/enterovirus (RV/EV) caused unexpected hospitalization.

In the delta period, 44,940 emergency department visits were recorded. Of those, 4.7% can be attributed to COVID-19. Among the COVID-19 cases, 28.8% were pediatric patients (0-4 years of age); Of these, 17.6% were hospitalized. Of all cases of COVID-19 during this delta period, 0.9% were diagnosed with diphtheria.

15,423 ED visits occurred during the Omicron period, of which 12% were associated with COVID-19. Among the patients infected with COVID-19, 51.2% were children (0-4 years) – this translates to a 77.8% increase in the proportion (cases of COVID-19 in this age group) compared to the delta period. Of those children infected with COVID-19, 16.1% were hospitalized. 10.8% of those infected were diagnosed with diphtheria – a 12-fold increase in the COVID-19-related group.

Overall, 36 patients with diphtheria underwent RVP multiple testing; 66.7% tested positive for SARS-CoV-2. Among the patients infected with SARS-CoV-2, 24 patients with a mean age of 12 months – 18 were male and six were female. While 10 were Caucasians, seven were African American, five were Hispanic, and two were Asian.

Of those 24 patients, 11 were hospitalized – two in the intensive care unit (ICU) and one requiring supplemental oxygen with heliox. The median length of hospital stay (LOS) was 24 hours and patients were managed according to the standard treatment protocol for diphtheria.


Compared with the SARS-CoV-2 Delta variant, the Omicron variant has greater transmissibility. It was observed that the cluster associated with SARS-CoV-2 presentation significantly increased in frequency during the Omicron phase of the COVID-19 pandemic. In addition, the diagnosis of COVID-19 nearly doubled among children aged 0-4 years during the Omicron period compared to the Delta period.

Therefore, the importance of vaccination efforts cannot be neglected, especially among this vulnerable group. Furthermore, distension of the upper respiratory tissue was demonstrated by the Omicron variant. This virus helps in adapting to new tissues to improve their suitability to enable better survival and increase transmissibility. Sweden recently reported several cases of pharyngitis and laryngitis among young adults during the Omicron-dominant period – indicative of the development of tissue swelling of the pathogen.

The results supported the SARS-CoV-2 diphtheria syndrome mimicking diphtheria due to other respiratory viruses, which spiked in frequency during Omicron’s dominance. In addition, a significantly increased incidence of diphtheria was recorded in younger children with COVID-19 during the Omicron period compared to the previous Delta period.

Thus, ongoing efforts to prevent the spread of COVID-19 to younger children have been validated, due to the negative effects of COVID-19 in this population.

2022-05-09 06:45:00

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