As physicians, other medical experts, and the public learn more about the 2019 Novel Coronavirus, or COVID-19, scientists are learning more about the similarities – and differences – between COVID-19 and influenza. Both viruses cause respiratory disease, yet the World Health Organization (WHO) reports there are important differences between the two and how they spread.
First, COVID-19 and influenza viruses have similar disease symptoms and a wide range of illness from mild to severe disease, and even death. Second, both viruses are transmitted by contact, droplets (from sneezes and coughs, for example), and contact with surfaces that can carry the infection, such as clothes, utensils, and furniture. As a result, common public health measures, such as cleaning high-contact surfaces such as door handles and handrails, washing hands, and coughing into your elbow or a tissue (and immediately disposing of the tissue), are important actions to prevent transmitting the disease to others. Doctors also recommend staying home if you are sick.
While the symptoms appear the same, there is a big difference between patients suffering a severe case of COVID-19 and influenza. The flu has a shorter incubation period from infection to diagnosable symptoms and can take 3 days to spread from person to person. The flu spreads faster than COVID-19, which can take 5 to 6 days to spread person to person. Also, flu can be transmitted before someone has symptoms, a major factor in the spread of influenza. As a result, children, pregnant women, elderly people, patients with chronic medical conditions, and those with compromised immune systems are most at risk to catch the flu.
The WHO reports a COVID-19 carrier can shed the virus 24 to 48 hours prior to symptom onset, reducing the threat of transmission to other people. Pre-symptomatic transmission of the flu is 3 to 5 days. However, when COVID-19 symptoms appear, the range of illness severity is proportionately different than the flu. WHO data suggests that 80% of COVID-19 infections are mild or asymptomatic, but 15% are severe infections requiring oxygen and 5% are critical infections requiring intensive care.
So, who is most at risk? Medical experts say people who are elderly, especially those with preexisting conditions, have an increased risk of getting sick from COVID-19. So far, the WHO says children, from newborn to age 19, are less likely to catch COVID-19. Additional studies in China also suggest that children who do catch COVID-19 are more likely to catch it from adults, rather than vice-versa. However, children play a major role in the spread of the flu.
Scientists are currently developing more than 20 COVID-19 vaccines, but there are currently no licensed vaccines or therapeutics available. In contrast, antivirals and vaccines are widely available for influenza. While the influenza vaccine is not effective against COVID-19 virus, it is highly recommended to get vaccinated each year to prevent the flu.
To help Texas physicians defend Texans against COVID-19, TMA has established – and continuously updates – an online Coronavirus Resource Center. Visit texmed.org/Coronavirus.