Preventing and Extinguishing Pandemic Sparks
Although most pandemic preparedness activities focus on reducing morbidity and mortality after a pandemic has spread widely, certain activities may prevent and contain pandemic sparks before they become a wider threat. At the core of pandemic prevention is the concept of One Health, an approach that considers human health, animal health, and the environment to be fundamentally interconnected (Zinsstag and others 2005).1 Activities that focus on understanding and controlling zoonotic pathogens may prevent spillover events and subsequent pandemics (Morse and others 2012).
To understand the etiology of pandemics, important One Health activities include the surveillance of zoonotic pathogens of pandemic potential at the human-animal interface, the modeling of evolutionary dynamics, the risk assessments of zoonotic pathogens, and other methods of understanding the interplay between environmental changes and pathogen emergence (Paez-Espino and others 2016; Wolfe and others 2005). For example, the PREDICT project of the U.S. Agency for International Development (USAID) has invested a significant amount of resources in understanding and characterizing zoonotic risk (Anthony and others 2013).
Countries can focus their spark mitigation efforts on policies designed to control animal reservoirs; monitor high-risk populations such as people working at the animal interface (for example, those involved in animal husbandry, animal slaughter, and so on); and maintain robust animal health infrastructure, biosecurity, and veterinary public health capacities (Jonas 2013; Pike and others 2010; Watts 2004; Yu and others 2014).
Risk communications can play a significant role in the control of an emerging epidemic or pandemic by providing information that people can use to take protective and preventive action (WHO 2013c). The dissemination of basic information (such as how the pathogen is transmitted, guidance on managing patient care, high-risk practices, and protective behavioral measures) can rapidly and significantly reduce the transmission of disease.
The way in which risk communications are framed and transmitted matters a great deal; they must be clear, simple, timely, and delivered by credible messengers. Factors such as literacy rates, cultural sensitivities, familiarity with scientific principles (such as the germ theory of disease), and reliance on oral versus written traditions all have implications for how messages should be designed and delivered (Bedrosian and others 2016).
Public health officials also need to identify and address misinformation, rumors, and anxieties. This can be a significant challenge. During the 2014 West Africa Ebola epidemic, many communities reached for culturally familiar explanations of disease transmission and rejected disease control practices that clashed with their traditional healing and burial practices (Roca and others 2015). Still other individuals spread rumors about the source of the infection; for example, in Liberia some community leaders claimed that the disease was created by the government (Epstein 2014).
Rumors can impede disease control and can be amplified by mistrust of government officials, which is a significant challenge in LMICs with high levels of corruption or legacies of violent conflict and social division. Research has found that in unstable contexts, people tend to believe rumors that confirm their preexisting beliefs and anxieties (Greenhill and Oppenheim 2017). This finding suggests that countering rumors with facts alone will not be sufficient. Risk communications need to be both factual and empathetic, addressing unfolding events and underlying fears through the lens of community experiences, histories, and perceptions.
The effectiveness of risk communications is difficult to measure. However, previous risk communication efforts have brought forth overarching themes that may be beneficial during the next epidemic or pandemic. One notable model comes from a Nipah virus outbreak in Bangladesh in 2010. In that outbreak, investigators found that messages about the sources of infection and potential strategies to reduce risk were more effective when conveyed by trusted local leaders and in terms that were relevant and grounded in the shared experiences of the affected community (Parveen and others 2016).
Reducing Pandemic Spread
Once a pandemic has begun in earnest, public health efforts often focus on minimizing its spread. Limiting the spread of a pandemic can help to reduce the number of total people who are infected and thus also mitigate some of the indirect health and economic effects. Strategies to minimize pandemic spread include the following (Ferguson and others 2005):
Curtailing interactions between infected and uninfected populations: for example, through patient isolation, quarantine, social distancing practices, and school closures
Reducing infectiousness of symptomatic patients: for example, through antiviral and antibiotic treatment and infection control practices
Reducing susceptibility of uninfected individuals: for example, through vaccines.
During the prepandemic period, plans for implementing those measures should be developed and tested through simulation exercises.
Curtailing Interactions between Infected and Uninfected Populations
The methods for curtailing interactions between infected and uninfected populations include patient isolation, quarantine, social distancing practices, school closures, use of personal protective equipment, and travel restrictions.
The practice of quarantine began in the fourteenth century in response to the Black Death and continues today (Mackowiak and Sehdev 2002). Quarantine and social distancing (such as the prohibition of mass gatherings) during the 1918 influenza pandemic reduced spread and mortality rates, particularly when implemented in the early stages of the pandemic (Bootsma and Ferguson 2007; Hollingsworth, Ferguson, and Anderson 2006). During SARS and Ebola outbreaks, health agencies and hospitals limited disease spread by isolating symptomatic patients, quarantining patient contacts, and improving hospital infection control practices (Cohen and others 2016; Twu and others 2003). During the 2003 SARS pandemic, none of the health care workers in hospitals in Hong Kong SAR, China, who reported appropriate and consistent use of masks, gloves, gowns, and hand washing (as recommended under droplet and contact precautions) were infected (Seto and others 2003).
Travel restrictions are sometimes implemented by governments to curtail disease spread. Fear and lack of scientific understanding may motivate the imposition of travel restrictions (Flahault and Valleron 1990). As such, these measures are sometimes implemented for inappropriate pathogens or too late to contain an outbreak and can cause substantial economic damage and public anxiety. Travel restrictions are more beneficial for pathogens that do not have a significant asymptomatic carrier state and have a relatively long incubation period (for example, SARS and Ebola). However, such restrictions may be of limited efficacy for influenza pandemics unless initiated when there are fewer than 50 cases at the spark site (Ferguson and others 2005).
Reducing Infectiousness and Susceptibility
Vaccines, antibiotics, and antiviral drugs can play a critical role in mitigating a pandemic by reducing the infectiousness of symptomatic patients and the susceptibility of uninfected individuals. Antivirals may reduce influenza transmission, although the extent of their effectiveness is unclear (Ferguson and others 2005; Jefferson and others 2014). A systematic review of clinical trial data among treated adults showed that oseltamivir reduced the duration of influenza symptoms by 17 hours, but prophylaxis trials found no significant reduction of transmission (Jefferson and others 2014).
If available, vaccines can reduce susceptibility. Significant efforts have focused on speeding up vaccine development and scaling up production. However, the availability of vaccines—particularly in LMICs—depends on the affected area’s capacity for distribution (including the scale and integrity of the cold chain), its capacity for last-mile delivery to rural areas, and the population’s willingness to adopt the vaccine. Vaccination strategies targeting younger populations may be especially beneficial, in part because influenza transmissibility is higher among younger populations during pandemics (Miller and others 2008).
The effectiveness of antivirals, antibiotics, and vaccines in reducing spread diminishes if the pandemic is already global, if LMICs cannot afford adequate vaccine stocks for their populations, or if specific populations (for example, the poor or the socially vulnerable) cannot access vaccines. Additionally, pandemics may be caused by a pathogen without an available vaccine or efficacious biomedical therapy. Efforts to improve the vaccine development pipeline are underway).