This time last year, the United States was in the grips of one of the biggest outbreak scares in recent memory. It was on September 30, 2014 that an Ebola patient was diagnosed on our shores for the first time. But another date deserves more attention: October 20, 2014. That was the day the Centers for Disease Control and Prevention, after insisting that American hospitals were equipped to treat Ebola patients and that workers needed no protection against the transmission of Ebola through the air, was forced to do an about-face after two Dallas nurses contracted Ebola from their patient.
The story of how the CDC arrived at that point — only the most visible instance of a series of missteps — is the subject of my in-depth investigative article published earlier this year in The New Atlantis (“The Ebola Gamble,” Spring 2015). The CDC and other public health authorities made unqualified claims about Ebola, claims that were repeated with such certainty by officials and some journalists that they practically became a set of talking points with only tenuous relation to the available science. These talking points were themselves the basis for numerous aspects of the public health response, from the 21-day quarantine period, to the lack of quarantine for asymptomatic Ebola workers, to the initial recommendation against workers wearing respirators. Many of these confident claims turned out to be wrong, oversimplified, or uncertain, largely on the basis of evidence available at the time.
To get a sense of just how wrong the official pronouncements were one year ago, it is worth cataloguing a few of the most pervasive and misleading claims:
Claim 1: Ebola spreads only by direct contact with the bodily fluids of an infected person. This was the central claim about the disease repeated by CDC director Thomas Frieden, and by many other officials and journalists. In fact, the CDC’s own fact sheets acknowledged the possibility of indirect transmission via medical equipment, doorknobs, toilets, and other surfaces, for days after they come into contact with infected bodily fluids.
Claim 2: You can’t get Ebola through the air. This widespread claim was the basis for the initial refusals by the CDC and the World Health Organization to recommend that workers treating Ebola patients wear respirators, and their insistence that one could not catch the disease by sitting next to an infected person on the bus or subway. The claim was based in part on equivocation: splashes of bodily fluids fall under the medical label of droplet or contact rather than airborne transmission, but CDC fact sheets include the unqualified claim “Ebola virus is not spread through air,” a misstatement in any ordinary interpretation of the English language. And officials offered a series of unclear and conflicting statements about whether Ebola could spread via coughs or sneezes.
These interpretations were themselves based on overstatements of the clarity of the limited available evidence about transmission through the air. This evidence was strong enough to rule out aerial transmission (including coughs, sneezes, and ordinary breathing) as the primary way that Ebola is transmitted, but it was far from sufficient to claim that aerial transmission is impossible or even uncommon. Indeed, a February 2015 literature review by twenty-one researchers, including many of the most respected names in the field, concluded, “It is very likely that at least some degree of Ebola virus transmission currently occurs via infectious aerosols.”
Claim 3: Ebola is contagious only when infected individuals are symptomatic. When people ill with Ebola become symptom-free and no longer show the virus in their blood, doctors and journalists often describe them as “cured” or “Ebola-free.” In fact — as was sometimes acknowledged but often ignored during the height of the outbreak — Ebola can stick around in the body long after the symptoms are gone. Ebola persists in semen for months after illness, and the first documented case of sexual transmission was reported earlier this year, to a woman whose partner’s symptoms had ended months before. Doctors also learned during the outbreak that the virus may persist in the fluid of the eyes for months after illness.
The February 2015 literature review also noted some documented cases of transmission from people only showing the limited early symptoms of the disease. Moreover, studies from the 1970s and 1980s found Ebola antibodies in 6 to 14 percent of West African populations despite no known outbreaks, suggesting “the possibility of … persistent, if latent, Ebola infection in humans.” And a 2000 study in The Lancet claimed to have found positive evidence for asymptomatic infection and transmission — in other words, evidence that Ebola may sometimes be a carrier disease.
Claim 4: Ebola has a maximum incubation period of 21 days. Along with the evidence mentioned that Ebola may sometimes cause contagious infection without creating any symptoms at all, a Drexler University researcher has traced the origin of the 21-day figure for Ebola incubation, finding that it was developed in response to the limited data available from the first outbreaks in the 1970s, and has not been carefully examined since. His analysis of the epidemiological data concluded that between 0.2 and 12 percent of infected individuals do not develop illness until more than 21 days after exposure. Relatedly, just this month, a Scottish nurse, who contracted Ebola in December 2014 but seemingly beat the disease, fell ill again, in what appears to be the first known case of relapse.
Claim 5: The CDC did not change its protection guidelines. Among the strangest and most telling misstatements related to the outbreak was the CDC’s characterization of its own policy shifts. In a public video statement explaining the new guidelines issued on October 20, 2014, and in response to my request to explain the rationale for the changes, CDC spokespersons described the new guidelines as “updated,” “clarified,” and “more detailed” versions of the previous guidelines. These statements falsely suggest that the guidelines did not substantively change. In fact, the new October 20 guidelines reversed the previous recommendation against workers wearing respirators when providing routine care to Ebola patients.
It’s the norm in science that tentative initial conclusions are qualified and revised as new evidence emerges. But these claims were offered by authorities and even many journalists as if Ebola, which has been known for less than forty years, and which saw only 2,400 human cases prior to the current outbreak, were as studied and reliable as smallpox or influenza. Their claims were based not on a frank reading of the science but a desire to reassure the public — an approach that Peter Sandman, a risk-communication researcher, summarized as “don’t scare the children.”
As our investigative article “The Ebola Gamble” describes, many reputable scientists at the time warned of the CDC and WHO’s overconfidence, pointing to the evidence contradicting their statements and policies. These critics urged that the recommendations against Ebola workers wearing respirators placed doctors and nurses at needless risk. But the critics faced pushback, both from colleagues and from the CDC and WHO. In one case, a WHO doctor was pressured by top leadership at the agency to remove his name from the literature review that concluded Ebola infection can probably spread through the air to some extent.
The most misleading belief afoot during the Ebola outbreak was that the public health response was based on rigorous readings of the science, unsullied by political concerns. Though the CDC and WHO have been widely derided for their weak and sluggish responses, it has gone largely unnoticed that the organizations were not simply caught off-guard but ignored and squelched the warnings of scientists at the time, apparently in the interests of safeguarding their reputations and tamping down a largely imagined hysteria.
The relative weakness of Ebola’s infectivity, and the general strength of the health care system in the United States, meant that Ebola was never likely to cause a large outbreak here. But this is of little consolation to the health care workers whose infections might have been avoided, both here and in West Africa — indeed, even today the WHO has not yet adopted the CDC’s updated respirator recommendations. In the future, a more resilient disease may prove less forgiving of such overconfidence. Ebola was a warning we have yet to heed.
Untruths We Were Told about Ebola