Virology: Current Research

The Emergence of Ten SARS-CoV-2 Variants and Airborne PM_2.5

Abstract

Yves Muscat Baron* and Liberato Camilleri

Background: The atmospheric pollutant PM_2.5 has been implicated in the pathogenesis of COVID-19. Some of the variants of SARS-CoV-2 possess the attributes of increased transmissibility and immune escape and appear to have been naturally selected to promulgate the pandemic. Variants of SARS-CoV-2 resulted due to a number of persistent SARS-CoV-2 mutations found in widely disparate and distant regions. This paper examines a possible association between airborne pollutant PM_2.5 and the emergence of ten SARS-CoV-2 variants.

Methods: The daily mean levels of PM_2.5 of a number of cities, where SARS-CoV-2 variants were detected, were obtained from the World Air Quality Index (WAQI). The mean daily PM_2.5 levels were evaluated just before the occurrence of the first cluster of PM_2.5 peaks’ atmospheric concentration, till after the emergence of the SARS- CoV-2 variants. Where available the daily number of new cases of COVID-19 diagnosed was matched to the PM_2.5 levels.

Results: There appears to be a common pattern of PM_2.5 in most of the regions prior to the emergence of the SARS-CoV-2 variants. An initial cluster of PM_2.5 peaks was noted on average 50 days prior to the emergence of the variants and another group of smaller peaks in PM_2.5 were noted just before or contemporaneous with the emergence of the SARS-CoV-2 variants. In the regions where the quantity of daily new cases was available, a number of significant correlations were obtained between PM_2.5 levels and the number of new cases of SARS-CoV-2 variants.

Conclusion: In most regions two clusters of PM_2.5 peaks were noted prior to the emergence of SARS-CoV-2 variants. The first cluster of PM_2.5 peaks may suggest that anthropogenic activity was increased possibly reflecting augmented human to human contact. Due to elevated levels of PM_2.5, a consequent propagation of the respiratory ACE-2 receptor (port of viral entry into the cell) ensued. Coronavirus- laden PM_2.5 may have induced intra-host mutagenesis in the SARS-CoV-2 genome, contemporaneously diminishing pulmonary immunity. With the second cluster of PM_2.5 peaks, this airborne pollutant may have also acted as a viral vector. The above findings suggest that antecedent peaks in PM_2.5 prior to SARS-CoV-2 variants’ emergence not only contributed to transmission, but also impacted the immediate viral environs which may have led to SARS-CoV-2’s natural selection.