Covid Variants Flu

About Covid Variants Flu

COVID and influenza are both respiratory viruses but differ significantly. SARS CoV 2 has a higher R0 than seasonal influenza, a longer incubation period of about 5 days for early variants versus about 2 days for flu, and a higher rate of asymptomatic transmission. Coronaviruses have a proofreading enzyme and mutate more slowly per replication than influenza, but the vast number of SARS CoV 2 infections allowed rapid evolution. Seasonal influenza has an estimated infection fatality rate of around 0.1 percent. Early in the pandemic, before vaccines, reported COVID case fatality ratios were often in the range of 1 to 2 percent. Both viruses undergo antigenic drift, but coronaviruses also recombine. Seasonal flu vaccines have been estimated at roughly 40 to 60 percent effective in well matched seasons and are reformulated yearly. Early COVID vaccine trials reported around 95 percent efficacy against symptomatic disease, though protection waned over time. Both viruses can cause pandemics, but COVID demonstrated that a novel respiratory virus can shut down the global economy in a way that influenza has not since 1918. The comparison between COVID and influenza shaped public perception and policy during the pandemic.