Chronic sinusitis has emerged as a significant concern during the COVID-19 pandemic, presenting in various forms. Understanding the relationship between COVID-19 and sinusitis is crucial for effective management. This narrative literature review aims to analyze the available evidence on the association between COVID-19 and sinusitis, offering insights into the best clinical practices.

The review examined articles from Scopus, PubMed, and Google Scholar, along with a manual search. Using keywords such as "sinusitis," "invasive," "COVID-19," "risk factors," "fungal," "rhinosinusitis," and "pathogenesis," the initial search yielded 285 articles. After applying inclusion and exclusion criteria (English language, peer-reviewed, full-text access), 96 papers were included in the review.

A comprehensive literature search was conducted across Scopus, PubMed, and Google Scholar databases. A manual search was also performed to identify potentially relevant articles. The research team initially identified keywords based on Medical Subject Headings (MeSH) terms, searching for articles individually and in various combinations. The review included only full-text, peer-reviewed articles published in English. Articles not in English or without peer review were excluded. The initial search yielded 285 articles, which were narrowed down to 96 articles for the review based on the inclusion and exclusion criteria.

The association between chronic rhinosinusitis (CRS) and COVID-19 showed conflicting results. Some studies indicated no association between CRS and severe COVID-19 or increased risk of infection, while others reported a significant association between CRS and increased risk of COVID-19 hospitalization. Regarding pathogenesis, chronic rhinosinusitis is linked to increased risk of sepsis, pneumonia, and mortality, potentially due to reduced nitric oxide production, viral/bacterial reservoirs, and impaired immune response. COVID-19 frequently causes olfactory dysfunction (5%-85% of cases), usually reversible, although some cases may persist. A significant association was observed between COVID-19 and acute invasive fungal rhinosinusitis (AIFR), with a substantial increase in AIFR cases reported during the pandemic. Diabetes mellitus (DM) emerged as the most common risk factor for AIFR, followed by steroid use and COVID-19-induced immunosuppression. Increased serum ferritin levels were also associated with increased risk of mucormycosis among COVID-19 patients. Ethmoid sinuses were the most commonly involved paranasal sinuses in AIFR cases.

The findings highlight the complex relationship between COVID-19 and sinusitis. While the association between CRS and severe COVID-19 remains inconclusive, necessitating further research, a clear link between COVID-19 and AIFR is evident. The high prevalence of DM and steroid use as risk factors for AIFR underscores the importance of managing these conditions in COVID-19 patients. The frequent involvement of the ethmoid sinuses in AIFR suggests a potential focal point for infection and warrants further investigation. The conflicting results regarding CRS and COVID-19 severity highlight the need for larger, well-designed studies to clarify this association.

This review underscores the significant association between COVID-19 and AIFR, highlighting DM and steroid use as major risk factors. Further research is needed to clarify the complex relationship between CRS and COVID-19 outcomes. Future studies should focus on larger patient cohorts, standardized diagnostic criteria, and longitudinal follow-up to improve understanding and management of sinusitis in the context of COVID-19.

The study's limitations include its narrative review design, which may be subject to bias in the selection and interpretation of studies. The heterogeneity in study designs and methodologies among the included articles limits the ability to draw definitive conclusions. The reliance on published literature may also lead to publication bias, potentially underrepresenting studies with negative findings. More research with larger sample sizes and consistent methodologies is needed to confirm the findings and address the inconsistencies observed.