Reflections on New York City's 1947 Smallpox Vaccination Program and Its 1976 Swine Influenza Immunization Program

In 1947, a smallpox outbreak occurred in New York City with a total of twelve cases and two deaths. In order to contain this outbreak, the New York City Department of Health launched a mass immunization campaign that over a period of some 60 days vaccinated 6.35 million people. This article examines in detail the epidemiology of this outbreak and the measures employed to contain it. In 1976, a swine influenza strain was isolated among a few recruits at a US Army training camp at Fort Dix, New Jersey. It was concluded at the time that this virus possibly represented a re-appearance of the 1918 influenza pandemic influenza strain. As a result, a mass national immunization program was launched by the federal government. From its inception, the program encountered a myriad of challenges ranging from doubts that it was even necessary to the development of Guillain-Barré paralysis among some vaccine recipients. This paper examines the planning for and implementation of the swine flu immunization program in New York City. It also compares it to the smallpox vaccination program of 1947. Despite equivalent financial and personnel resources, leadership and organizational skills, the 1976 program only immunized approximately a tenth of the number of New York City residents vaccinated in 1947. The reasons for these marked differences in outcomes are discussed in detail.

Smallpox as a Weapon for Bioterrorism

Smallpox, the only disease ever eradicated, is one of the six pathogens considered a serious threat for biological terrorism (Henderson et al., 1999; Mahy, 2003; Whitley, 2003). Smallpox has several attributes that make it a potential threat. It can be grown in large amounts. It spreads via the respiratory route. It has a 30% mortality rate. The potential for an attack using smallpox motivated President Bush to call for phased vaccination of a substantial number of American health care and public health workers (Grabenstein and Winkenwerder, 2003; Stevenson and Stolberg, 2002). Following September 11, 2001, the United States rebuilt its supplies of vaccine and Vaccinia Immune Globulin (VIG), expanded the network of laboratories capable of testing for variola virus, and engaged in a broad education campaign to help health care workers and the general public understand the disease (Centers for Disease Control and Prevention, 2003a). This chapter summarizes the scientific and theoretical bases for use of smallpox as a bioweapon and options for preparation for defense against it.

Smallpox vaccines for biodefense: need and feasibility

Smallpox, eradicated as a cause of natural disease through an intensive global effort in the later part of the 20th Century, has resurfaced as a possible agent of bioterrorism. For this reason, there is renewed interest in smallpox vaccines. Live vaccinia virus, an orthopoxvirus related to smallpox, has a long and successful clinical track record as an effective smallpox vaccine; however, its use is associated with uncommon yet serious adverse events. This has led to a surge of recent research into newer-generation smallpox vaccines with improved safety profiles and retained efficacy. This article will review the history of smallpox vaccines, assess the status of newer-generation vaccines and examine the overall risk-versus-benefit profile of smallpox vaccination.

New generation smallpox vaccines: a review of preclinical and clinical data

The recognition that smallpox is a potential threat agent of bioterrorism has engendered renewed interest in the development of improved vaccines against this pathogen. The purpose of this paper is to review current data regarding novel approaches to smallpox vaccines in comparison with traditional vaccine strategies. The method used is a literature search using overlapping search terms and citations from the relevant, published literature. Substantial animal and limited human data suggest that selected second and third generation smallpox vaccines, specifically tissue-cultured vaccinia virus and replication-competent, highly attenuated vaccinia virus possess immunogenicity and surrogate efficacy profiles similar to those of first generation New York City Board of Health and Lister vaccines. Replication-defective, attenuated vaccinia appears to be less immunogenic in both animals and humans but may have utility as a priming agent in those with contraindications to live vaccinia. There is a clear risk of myopericarditis with first and second generation products, but the relative risk of this complication among various vaccine approaches cannot as yet be determined. The incidence of other serious, albeit uncommon, adverse events of smallpox vaccines cannot be determined for newer vaccine approaches because these agents have not yet been deployed on a scale large enough to discern rare events. Since 2001, progress towards improved smallpox vaccines has been accelerated, spurred on by the threat of bioterrorism. Among newer vaccine candidates, replication-competent, highly attenuated vaccinia and tissue culture-derived live vaccinia appear to offer the greatest potential for efficacy, although it is unclear whether these products offer a safer alternative to existing first generation vaccines.

The smallpox vaccine

BACKGROUND

A heightened awareness of the potential for bioterrorist attacks in the United States has led to the expansion of the nation's supply of smallpox vaccine and the institution of procedures to distribute this vaccine in the unlikely event of a release of this potentially deadly agent.

METHODS

The authors conducted a review of the relevant smallpox literature through a MEDLINE search. They also reviewed the Web site of the Centers for Disease Control and Prevention and numerous other Web sites.

RESULTS

The authors considered for inclusion more than 100 articles discussing smallpox, the smallpox vaccine and the role of the dental professional in a bioterrorist attack.

CONCLUSIONS

Dentists may detect the initial signs of a smallpox infection, provide information concerning the disease to the public and potentially assist in the administration of smallpox vaccine.

CLINICAL IMPLICATIONS

Should an intentional release of smallpox occur, the dental professional may play an important role in its treatment and prevention.

Pre-event willingness to receive smallpox vaccine among physicians and public safety personnel

BACKGROUND

Planning for voluntary smallpox vaccination of health and safety officials began in December 2002.

MATERIALS AND METHODS

Surveys were conducted among physicians and fire and police department personnel in Atlanta, Georgia. Information on demographics, willingness to receive smallpox vaccine, self-reported knowledge level, and potential vaccine contraindications was analyzed.

RESULTS

Forty-one percent of physicians (n = 199) were undecided on vaccination (32% would receive vaccine and 27% would not). Forty-eight percent of firefighters (n = 343) and 41% of police (n = 466) were undecided; 23% and 41% would receive vaccine, whereas 28% and 18% would not (fire and police, respectively). Absence of contraindications was associated with physicians' willingness to be vaccinated (P = 0.006). Many physicians (66%) and most public safety personnel (88%) considered themselves inadequately informed on smallpox vaccine. In a multivariate analysis, inadequately informed respondents were more likely to be undecided (OR = 2.23, CI = 1.39 to 3.56).

CONCLUSIONS

Before implementation of the smallpox vaccination program, self-assessed knowledge about smallpox disease and vaccine were poor.

Prediction of smallpox outbreak and evaluation of control-measure policy in Japan, using a mathematical model

Since the September 1 terrorist attacks and moreover, since the anthrax exposure events in 2001 in the United States, bioterrorism attacks seem to be a real threat. Of course, the public health authorities in Japan have started to prepare control measures for such events. We report here our attempts, using a mathematical model, to estimate outbreak size and to examine the most effective measures; comparing ring vaccination (contact tracing, isolation, and vaccination among contacts) and mass vaccination of the susceptible population in the area. The basic framework of the mathematical model follows a model used in previous research. The initial susceptible population is assumed to be 30 million persons. Concerning the important parameters, such as the number of initial-exposure cases, R₀ (infectious power, or natural history) and, the starting day of intervention after the initial exposure, we checked the robustness of our conclusions by sensitivity analysis. We found that mass vaccination is preferable to ring vaccination when the values for the initial-exposure cases and R₀ are high and when the start of intervention by public health authorities is delayed. In the base-case situation, the mass vaccination strategy needs almost 30 million vaccine doses. On the other hand, though ring vaccination needs fewer doses, it needs fewer than 50 000 doses in the worst-case scenario, that with larger first exposure, higher R₀, or later start of public health authority intervention. This mathematical model can measure the prevalence of an infectious disease and can evaluate control measures for it before an outbreak. Especially, it is useful for the planning of the outbreaks of emerging diseases such as severe acute respiratory syndrome (SARS) or for bioterrorism attacks involving such diseases as smallpox. In further research, we will have to take into account the population people vaccinated of for smallpox, who account for about 70% of the total population in Japan.

Risque de variole, vaccination et bioterrorisme

The use of the smallpox virus as a biological weapon is very old. Confronted with a high probability of a current bioterrorist menace, counteracting strategies have been developed. One of the principle aims relies on the vaccination of teams dedicated to the management of persons infected and the stocking of vaccine for the whole population of a country. Following worldwide eradication of the disease, preventive vaccination was topped in 1978 in France for the primo-vaccination, and in 1984 for repeat vaccinations. The various strains used in the first generation vaccinations are weakened living vaccine, the natural host and origin of which is unknown. Second and third generations vaccines are under study; the principle objective is to obtain efficacy with a minimum of side effects. There are two types of adverse events, generally observed with the first generation vaccines: the first, extremely rare, can be life-threatening; the others, more frequent (10 to 15% of patients) are benign. In emergency situations, in the presence of smallpox, there should be no absolute contraindications to vaccination. In the bioterrorist context, massive vaccination campaigns of the population are unadvisable (because of the considerable risk of death and severe adverse events) in the absence of any real permit, in each case, definition of the vaccinal strategy to be adopted.