Editorial

COVID-19 unlikely to behave like 1918 Spanish flu

COVID-19 is more lethal than the seasonal flu. But there are no signs it will be as catastrophic as the worst pandemic the 1918 Spanish flu.

The 1918 flu is the quintessential pandemic, estimated to have killed 50 million people worldwide. Although it occurred in an era before international air travel, its movement around the globe was facilitated by troops fighting in World War I. It went around the world four times in one year when there were no airplanes. That’s what it means to spread like wildfire.

The 1918 flu was unusually bad for targeting healthy people, with fatalities high in those younger than 5, between the ages of 20 and 40 and those 65 and above. The new coronavirus, by contrast, has so far spared babies, toddlers and young children from death. It’s estimated to be mild in about 81% of those infected. The risk of death is substantially higher for those aged 70 and older and those with underlying medical problems.

Fatality rate for the 1918 flu was > 2.5%. In the early months of the coronavirus outbreak, the fatality rate held steady at around 2.3%. This week, it inched up above 3.4%.

The case fatality rate of the 1918 Spanish flu also varied between countries, with poorer ones taking a bigger hit. In the U.S., mortality also differed by economic status: the lower the economic level, the higher the attack rate. People of lower socioeconomic status are more likely to have chronic health conditions that would make them more vulnerable to an influenza infection. Fatality rates can also be affected by how well or how poorly public health officials respond to outbreaks.

For instance, in the first months of the coronavirus outbreak, Chinese authorities allowed crowds to gather in tight spaces for Lunar New Year celebrations even though it was clear the new virus was circulating. They also let 5 million people flee the Wuhan area just before enforcing an unprecedented regional quarantine.

The underlying health of the population matters too. Some experts suspect that high smoking rates among Chinese men may help explain why some studies have reported that men who are infected are more likely than women to die of COVID-19.

Back in 1918, those who were infected did not have the benefit of the medicines available today. Antibiotics hadn’t yet been invented, and that was a problem because most of the people with the flu died of secondary bacterial infections.

At this time, there’s no evidence that secondary bacterial infections are a major complication of the new coronavirus.

The overall clinical consequences of the new coronavirus may ultimately be more like a severe seasonal flu, or one of the flu pandemics the world saw in 1957 and 1968.

Each of those flu pandemics resulted in about 1 million deaths worldwide, and about 100,000 deaths in the U.S.

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA