Seasonal Irritants. Coronavirues are seasonal irritants, with four – alpha genus CoV-229E & CoV-NL63 and beta genus CoV-HKU1 & CoV-OC43 – causing the common cold. They are seasonal because, like many viruses such as seasonal or winter flu (the clue being in the name), they need environmental factors to sustain their virulence and therefore maintain […]
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