It has been found by researchers that the release of interferons is necessary for the body to activate an immune response on encountering a virus. But on being exposed to the COVID-19 virus, the body doesn't increase the production of interferons as it does with other viral diseases and hence we do not see symptoms until 7-10 days after infection. It has been thought that the SARS-CoV-2 virus may hide its genomic material from being recognised in the alveolar macrophages, thereby not inducing the production of interferons. This allows the virus to spread further in the community before the appearance of symptoms.