One hundred years ago, a pandemic caused by a new virus sickened 500 million people and killed 50 million, including 670,000 Americans. Average U.S. life expectancy fell by 12 years. This catastrophe was not caused by a coronavirus, like the one currently ravaging China and raising fears around the world. Influenza virus, commonly known as the flu, was the culprit—and it remains, today, a far larger threat than coronavirus. Some perspective is in order.
Familiarity breeds complacency—“oh, it’s just the flu”—but seasonal influenza is a serious public health problem, causing widespread illness, hospitalizations, and death. The Council of Economic Advisers recently estimated that in a typical flu season, 27 million Americans will get sick; 59,000 will die, while another 368,000 will be hospitalized. The total cost will be $361 billion per year, primarily due to the value of lives lost.
On occasion, new influenza viruses emerge containing significant genetic changes to which people have little or no immunologic memory or protection. These viruses can spread from person to person in an efficient and sustained way, leading to a pandemic with higher rates of illness, serious complications, and mortality than seasonal influenza. The past 100 years have seen four influenza pandemics—1918, 1957, 1968, and 2009—leading to worldwide deaths totaling, respectively, 50 million, more than 1 million, 1 million, and 151,700–575,000. The CEA estimates that a future influenza pandemic would cause $413 billion to $3.79 trillion worth of economic damage in the U.S., depending on the transmission efficiency and virulence of the pandemic virus. U.S. fatalities in the most serious scenario would exceed half a million.
By contrast, coronavirus infections in humans have generally been associated with mild illnesses such as the common cold. In three cases, more pathogenic coronaviruses jumped from animals to infect humans. A coronavirus variant identified in China in 2002 caused a new disease: severe acute respiratory syndrome. SARS spread via international travel to more than 24 countries. Most human-to-human transmission occurred from symptomatic patients in health-care settings, though a few episodes of community transmission were reported. Public health measures ended the pandemic but only after 8,098 people were infected and 774 had died, according to Chinese government figures—though these are widely seen as lowball numbers.
A second highly pathogenic (36 percent fatality rate) coronavirus disease, Middle Eastern respiratory syndrome (MERS), was identified in 2012. It has not been associated with community spread but has been transmitted within health-care centers. To date, MERS has caused 2,494 cases and 858 deaths, primarily in Saudi Arabia.
The newest coronavirus (2019-nCov) was identified last month in Wuhan, China. The viral genome is 75 percent to 80 percent identical to the SARS virus and uses the same cellular receptor to infect human respiratory-tract cells. It is, therefore, likely that human-to-human transmission occurs through a similar mechanism as SARS, primarily in medical settings. As of February 1, almost 12,000 cases had been reported (nearly all in China), with 259 deaths (all in China), making 2019-nCov much less lethal than SARS or MERS. Only eight known cases exist in the U.S. thus far.
Despite its more serious outbreaks, coronavirus represents much less of a health threat than either seasonal or pandemic influenza. The public health measures that controlled SARS, including timely diagnosis and quarantine and strict adherence to universal precautions, will likely successfully contain 2019-nCov outside of China. Meantime, according to the CDC’s latest “Weekly U.S. Influenza Surveillance Report,” so far in the current flu season, which has four more months to run, 19 million Americans have gotten influenza, with 180,000 hospitalized and 10,000 deaths.
Annual vaccination is the most effective influenza countermeasure. Yet current vaccine manufacture, which largely depends on a lengthy production process in chicken eggs, would be too slow to respond to new pandemic threats and leads to low seasonal vaccine effectiveness. Over the past 15 years, vaccine effectiveness varied between 10 percent and 60 percent. Moreover, no matter how effective a vaccine is in preventing infection, it can work only if people get vaccinated. Unfortunately, over many years, the average population-wide vaccination rate reaches only 45 percent.
Faster vaccine-production methods that would make vaccines more readily available for unexpected pandemic threats and that may lead to more effective vaccines by better matching of the vaccines to circulating viruses have been developed through public-private partnerships, but they have not been widely adopted. In September 2019, President Trump signed an executive order promoting the use of these new methods and the development of others to make vaccine manufacture faster and produce a more effective product. The order also seeks ways to increase influenza vaccination across the population.
Faster production of more effective influenza vaccines that will be administered to more people will not happen overnight. But we should not be distracted from these priorities by the far less significant threat of coronavirus.
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