The epidemiology of Fearbola

In the mid-19th Century, a newspaper could reach several thousand people daily or weekly. By the mid-20th Century, TV and radio reached 10s to 100s of millions of people instantaneously and possessed a multinational reach. Today, with the Internet, and satellite TV and radio, it is possible to reach 100s of millions of people or more across the globe within minutes. This vast and practically instantaneous reach of technology feeds a seemingly insatiable, 24/7 appetite for news and information. What are the implications of this for fighting epidemics? 

We've seen some of the consequences in the Ebola outbreak this year. On the one hand, the ability of aid groups to spread information broadly has been helpful for raising awareness and bringing additional resources to bear on the epidemic. On the other hand, news headlines resulted in near-hysteria and much counterproductive behavior in the US and other developed nations. Examples were highlighted in a previous post, and many, many others have offered similar observations and commentary.

Perhaps the reactions observed in the US have been understandable, as many ingredients were present for an epidemic of sensationalism and fear: An active public imagination rooted in previous popular books and movies, a government that addressed the issue late and with almost Pollyannaish credibility at first, and a wealth of news outlets offering non-expert commentary while playing to the continuous news cycle.

The resulting epidemic of "Fearbola" should thus not be surprising. It is sobering, however, for it provides a warning for domestic public health agencies: Understand how to administer effective public health messages that are relevant and appealing to the constant clamor of CNN, Fox, and the like, or else risk being drowned out by noise and hype. What if this epidemic had been of a pathogen possessing a short serial interval and high virulence, transmissibility, and R₀? The medical system may or may not be prepared, but it seems clear that our risk communication strategies are not. Would the news coverage we saw during the Ebola hysteria in recent months have served the public well if this had been a bona fide threat to US public health?

It's important to understand how the epidemic of fear and hype came into being and propagated so well. I tend to think of messages as themselves being infectious. From that perspective, the ideas that resulted in the hysteria surely had R₀ > 1. For ideas related to "dread threats", such as virulent infections with no known cure, is this unavoidable given the high contact rate (e.g., frequency of checking for news and rumors combined with near-constant coverage), short serial internal (e.g., rush to post on social media), broad coverage, and rapid dissemination of modern communications?

If so, we must learn how to craft public health messaging strategies so that authoritative messages will out-compete hype and fear in our hyper-connected world. If we don't learn how to do so, we run the risk that important messages will be drowned out by high-incidence, fearful messages in future outbreaks of international public health importance.

(image source: David Hartley)

Influenza vaccine recommendations: Stop needling me!

Seasonal influenza is responsible for an estimated 200,000 hospitalizations and 23,000 deaths in the US annually. Each year influenza vaccines are produced based on the viruses forecast to become prevalent. There are two types of vaccine: inactivated influenza vaccine (IIV), delivered via injection, and live attenuated influenza vaccine (LAIV), delivered via a mist sprayed into the nose. Influenza vaccines typically have efficacies exceeding 60% and an estimated 46% of the American public relieves vaccine annually.

While many people are vaccinated each year, it is desirable to increase vaccination rates for at least two reasons. First, vaccine-associated immunity protects individuals from developing potentially serious or fatal disease. Second, high population coverage produces a herd immunity effect: those possessing vaccine-associated immunity cannot become infected and thus cannot infect others. This is especially important for protecting individuals for whom vaccines are contraindicated.

Individuals who are immunocompromised or immunosuppressed are such a group. Consider, for example, patients recovering from hematopoietic stem cell transplantation (HSCT) following myeloablative conditioning. In cases of imperfect donor-recipient match, patients may take immunosuppressive medications as prophylaxis against, or treatment for, graft versus host disease. During this process of immunologic tolerization, which can last months or longer, patients must avoid crowds and limit work/school and social interactions in order to avoid potentially fatal infections. And during this period it is critically important for caregivers and contacts to be vaccinated against influenza and other vaccine-preventable diseases so that they do not become infectious.

LAIV is contraindicated for caregivers of such persons in the Advisory Committee on Immunization Practices (ACIP) guidelines. Because LAIV contains live influenza viruses, a potential exists for transmission of vaccine strain viruses from vaccinees to other persons. The period of viral shedding in vaccinees is variable and relatively short lived. Vaccinated immunocompetent children, for example, shed vaccine viruses for less than 3 weeks, and evidence suggests that shedding may be much shorter lived than that. LAIV-associated shedding occurs in lower titers than is typically observed in disease-associated shedding caused by wild-type influenza viruses.

As several studies have demonstrated higher efficacy of LAIV relative to IIV in children (but see the footnote below), the ACIP has expressed

a preference for the use, when immediately available, of live attenuated influenza vaccine (LAIV) for healthy children aged 2 through 8 years, to be implemented as feasible for the 2014–15 season but not later than the 2015–16 season.

Higher protective efficacy of LAIV in children provides strong rationale for the ACIP statement. Moreover, promoting LAIV as an alternative to IIV in older patient populations may result in increased coverage in those who avoid vaccination due to fear of needles. I wonder if increased use of LAIV might pose additional risk to immunocompromised persons, however, in terms of inadvertent exposure to recent vaccinees shedding live, though attenuated, influenza viruses. Such patients may need to become more meticulous in screening visitors and contacts who may have received LAIV recently.

Footnote: During 2013-2014 there was no measurable effectiveness for LAIV against influenza A (H1N1) among children enrolled in effectiveness studies. The reasons for this are unclear.

(image source: Wikipedia)

Fearbola

Some people in the US have absolutely panicked over the threat of Ebola at home. To cite but a few examples:

• A Portland, Oregon, high school canceled a visit by African students, citing concerns about Ebola. The 18 visiting students came from Republic of Congo, Niger and Ivory Coast, none of which currently have reported cases of Ebola, according to the WHO.
• Two children who recently moved to the US from Rwanda are being kept home from school after parents at an elementary school in New Jersey voiced concerns. Rwanda is in East Africa, over 2,500 miles from the West African areas where Ebola virus is currently circulating.
• An assistant principal at a North Carolina middle school has to spend 21 days working from home when she returns from a mission trip to South Africa, by order of the school board. The chairperson of the school board explained why: "It’s not that we think that she poses any type of risk, but it's public perception here that we're concerned about.

More examples are described in a recent CNN article, which also notes that:

This is getting ridiculous. While the threat of Ebola is very real in Africa, the paranoia it's generated in the United States is unreal.

Many baseless actions are being taken out of "an abundance of caution", and it's not only in the US: A recent article by Andrew Higgins describes similar behavior in Europe.

While listening to the radio while working today, it struck me how someone having a case of air sickness on a commercial jetliner now makes the national news. Perception of risk is a notoriously sticky subject, but perhaps it's a good time to begin a conversation on how to educate people better on the topic. Could some basic elements of risk assessment be taught, for example, in high school?

(image source: Wikipedia)

Fear, Ebola, and the plague doctor's outfit

An earlier post mused that, in some ways, modern healthcare workers in contact precautions might appear as the plague doctors did in the Middle Ages to their febrile, terrified patients. The imagery of the plague doctor's outfit has survived centuries in association with a horrific event responsible for significant death and social disruption. Today, the doctor's outfit remains a powerful symbol of desperate times.

While the current epidemic of Ebola virus disease is unlikely to have the depopulating effect that plague did in the 1300s -- the Black Death is estimated to have killed up to 60% of the European population at the time -- the deadliness of this virus as it circulates in Western Africa must produce a fear similar to that of the Black Death in the Middle Ages. It makes me wonder if, years from now, pictures of doctors and nurses in Ebola personal protective equipment (PPE) -- the garb healthcare workers must wear to care for patients -- will conjure up similar reactions to those of the plague doctor's outfit.

Think of the similarities. If the case fatality rate (CFR) of plague in the 14th Century was similar to that of plague in the US between 1900 and 1941 (i.e., in the pre-antibiotic era), the CFR of the Black Death could have been over 60%. The CFR of Ebola in West Africa is currently estimated to be near 70%. Probably due to this high CFR during the Black Death, people were often deeply skeptical of doctors, as as Giovanni Boccaccio  describes in The Decameron:

Which maladies seemed set entirely at naught both the art of the physician and the virtue of physic; indeed, whether it was that the disorder was of a nature to defy such treatment, or that the physicians were at fault - besides the qualified there was now a multitude both of men and of women who practiced without having received the slightest tincture of medical science - and, being in ignorance of its source, failed to apply the proper remedies; in either case, not merely were those that covered few, but almost all within three days from the appearance of the said symptoms, sooner or later, died, and in most cases without any fever or other attendant malady . . . 

As we have read in this event, distrust of healthcare workers in Western Africa has led to attacks on doctors, though this sentiment may partially stem from historical events. Indeed, serious issues with healthcare in this region are nothing new.

Of course, there are important differences between bubonic plague in the Middle Ages and Ebola in Africa today as well. Plague is caused by a bacterium whereas Ebola virus disease has a viral etiology; Yersinia pestis is carried by domestic rodents and vectored to humans by fleas whereas Ebola virus is directly transmitted between humans; et cetera. Perception is reality, however, and one overarching public perception is proving a difficult to alter: Ebola is terrifying. Ebola PPE is a modern plague doctor's suit, a tangible symbol of fear, a fear that we have but to turn on any newscast to see spread.

I feel strongly that we must never forget the human dimensions of disease. Physiologically speaking, Ebola virus disease in Homo sapiens is increasingly well understood, but the impact of the disease on the human condition is perhaps less so. If we are to control the spread of Ebola virus, we must understand this better; it seems clear that we don't. Fear and panic only make the situation worse. We must control the fear.

(image source: Wikipedia and WHO)