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Cardiac adverse events following smallpox vaccination--United States, 2003.

During January 24-March 21, smallpox vaccine was administered to 25,645 civilian health-care and public health workers in 53 jurisdictions as part of an effort to prepare the United States in the event of a terrorist attack using smallpox. Seven cases of cardiac adverse events have been reported among civilian vaccinees since the beginning of the smallpox vaccination program. In addition, 10 cases of myopericarditis have been reported among military vaccinees. This report summarizes data on the seven cases reported among civilians and provides background information on recent military vaccinees. Although a causal association between vaccination and adverse cardiac events in the civilian population is unproven, as a precautionary measure, CDC recommends that persons with physician-diagnosed cardiac disease with or without symptoms (e.g., previous myocardial infarction, angina, congestive heart failure, or cardiomyopathy) be excluded from vaccination during this smallpox preparedness program.

Adult↗

Update: cardiac-related events during the civilian smallpox vaccination program--United States, 2003.

During the pre-event smallpox vaccination program, the U.S. Department of Defense (DOD) and CDC have received reports of cardiac events after vaccination. A case definition for myo/pericarditis as a smallpox vaccine--associated adverse event has been developed in conjunction with DOD, the joint Smallpox Vaccine Safety Working Group of the Advisory Committee on Immunization Practices (ACIP) and the Armed Forces Epidemiology Board (AFEB), and consulting cardiologists, immunologists, and epidemiologists. The term myo/pericarditis is used for surveillance purposes to refer to patients who have myocarditis, pericarditis, or both (myopericarditis). Myo/pericarditis cases are classified into suspected, probable, and confirmed categories. Suspected cases include those that are investigated and reported, although the level of certainty for the diagnosis is lower. These definitions were used to categorize all cardiac-related reports among civilian vaccinees received through May 9, 2003; a total of 21 cases of myo/pericarditis were ascertained. All have been reported previously; however, some have been reclassified. In addition, nine cases of ischemic cardiac events (i.e., myocardial infarction [MI] or angina) among civilian vaccinees have been reported previously. This report includes the case definition of myo/pericarditis and updates information on all reports of cardiac adverse events among 36,217 civilian vaccinees since the beginning of the civilian smallpox vaccination program reported through May 9 to CDC from the Vaccine Adverse Event Reporting System (VAERS).

Female↗

Update: cardiac and other adverse events following civilian smallpox vaccination--United States, 2003.

During January 24-June 20, 2003, smallpox vaccine was administered to 37,802 civilian health-care and public health workers in 55 jurisdictions to prepare the United States for a possible terrorist attack using smallpox virus. This report updates information on vaccine-associated adverse events among civilians vaccinated since the beginning of the program and among contacts of vaccinees, received by CDC from the Vaccine Adverse Event Reporting System (VAERS) as of June 20. Two cases of dilated cardiomyopathy (DCM) were diagnosed 3 months after vaccination. For the potential relation between smallpox vaccine and DCM to be assessed, identification of additional cases of DCM among vaccinees will be essential. Physicians who treat smallpox vaccine recipients are encouraged to evaluate and report patients with symptoms compatible with DCM, including those that occur several months after vaccination.

Adverse Drug Reaction Reporting Systems↗

Cardiac deaths after a mass smallpox vaccination campaign--New York City, 1947.

During the first wave of the 2003 smallpox vaccination campaign, two ischemic cardiac deaths occurred in civilian vaccinees aged 55 and 57 years, and one occurred in a military vaccinee aged 55 years, 4-17 days after vaccination with the New York City Board of Health (NYCBOH) vaccinia strain. Whether these and 13 other recognized military and civilian nonfatal ischemic events among vaccinees were associated with smallpox vaccination is unclear. The same NYCBOH strain was used in 1947 to vaccinate approximately six million New York City (NYC) residents (80% of the population) during a 4-week period (April 4-May 2) after a smallpox outbreak. To determine whether smallpox vaccination increased the risk for cardiac death in 1947, the NYC Department of Health and Mental Hygiene (DOHMH) analyzed data from NYC death certificates during that period. This report summarizes the results of that analysis, which found no increases in cardiac, atherosclerotic, or all-cause deaths. The findings are consistent with a growing body of evidence suggesting that ischemic cardiac deaths observed after the 2003 campaign might have been unrelated to vaccine.

Heart Diseases↗

[Tenth anniversary of smallpox eradication: Results of epidemiological and virological surveillance and studies in the post-eradication period].

In accordance with recommendations of the Global Commission on the certification of smallpox eradication for the 10-year period after the eradication of this infection, all suspected cases of smallpox have been thoroughly checked up, and in none of them the diagnosis of smallpox has been confirmed. The study of monkeypox in humans has revealed that this zoonosis is spread over a wider area than supposed earlier and covers 7 countries of Equatorial Africa, occurring most frequently in Zaire. In about 70% of cases of monkeypox in human the disease is contracted from animals serving as natural virus carriers and in about one-third of such cases, from humans having monkeypox. The infectivity of humans with monkeypox for persons having close contacts with them is somewhat lower (12.3%) than in smallpox when this characteristic varies from 37% to 88%. Monkeypox in humans may take an asymptomatic course. Some species of tropical squirrels serve as natural virus carriers. These investigations have also resulted in essential corrections being made in understanding the ecology of cowpox virus, another orthopoxvirus pathogenic for man. At least 5 species of rodents have proved to be of interest as natural carriers of cowpox virus.

Africa↗

[Study of the properties of a tissue smallpox vaccine manufactured by the Moscow Research Institute of Viral Preparations].

The tissue culture vaccine against smallpox has some important advantages over the dermal preparation: it is free from bacterial contamination, contains no serum proteins, and suitable for intradermal inoculation with jet injections. The virus for the tissue culture smallpox vaccine is grown in Japanese quail embryo cultures controlled for the absence of contaminating viruses. In trials of the tissue culture smallpox vaccine in 800 revaccinated volunteers no untoward reactions or complications were observed. The antigenic activity of the tissue culture smallpox vaccine was superior to that of dermal vaccine used in the same dose: the geometric mean neutralizing antibody titre after vaccination with the tissue and dermal preparations was 1 : 256 and 1 : 158, respectively, and the antibody rise was 4.5- and 2.5-fold.

Adult↗

Haemorrhagic smallpox. I. Preliminary haematological studies.

In an investigation of specific haematological defects that might account for the haemorrhagic diathesis in certain smallpox patients, 93 patients with haemorrhagic and non-haemorrhagic forms of the disease were subjected to a variety of bleeding and coagulation studies. The findings indicate that smallpox patients with no clinical evidence of haemorrhage have no significant clotting defects although many have decreased platelets and clot retraction abnormality. Patients with the late haemorrhagic form of smallpox consistently show thrombocytopenia and associated abnormalities in the bleeding time, tourniquet test and clot retraction; some also have slightly depressed specific prothrombin activity.Patients with the severe, and uniformly fatal, early haemorrhagic form have severe thrombocytopenia, a marked decrease in specific prothrombin activity and prolongation of the prothrombin complex times. They also have a marked prolongation of the thrombin time, suggesting the presence of a circulating antithrombin.Both early and late haemorrhagic smallpox patients also have a marked abnormality of prothrombin consumption, indicating impaired plasma thromboplastin production. This finding could be explained by the thrombocytopenia present in all haemorrhagic cases.

Blood Coagulation Disorders↗

Smallpox and monkeypox in non-human primates.

In considering global eradication of smallpox the absence of an animal reservoir is important. Present knowledge of experimental infection of non-human primates with variola virus and of a related virus infection in monkeys, termed monkeypox, is examined.From the literature review and the results of a survey of captive monkeys in 26 major biological institutions it is concluded that outbreaks of supposed smallpox and monkeypox are not frequent and that man may be comparatively insusceptible to monkeypox. A natural reservoir of smallpox in non-human primates is thought to be unlikely although further studies are warranted since the survey reveals that certain species of monkeys can be infected with smallpox and that infected monkeys can transmit infection to others.

Animals↗

An airborne outbreak of smallpox in a German hospital and its significance with respect to other recent outbreaks in Europe.

Since 1960, smallpox has been introduced into 10 European countries on 28 separate occasions. Most commonly, the index case was infected in Asia and returned to Europe by air during the period December-May. Subsequent cases have occurred mainly among persons exposed by direct, face-to-face, contact in the household or hospital. Medical and hospital personnel, patients and visitors constituted approximately half of all cases in these outbreaks.In a recent outbreak in Meschede, Federal Republic of Germany, detailed epidemiological studies have clearly indicated that 17 of the cases were infected by virus particles disseminated by air over a considerable distance within a single hospital building. Several features believed to be of importance in this unusual pattern of transmission were common to a similar outbreak in the Federal Republic of Germany in 1961 in which airborne transmission also occurred. These features include a source case with extensive rash and cough, low relative humidity in the hospital and air currents which caused rapid dissemination of the virus. While airborne transmission of this sort is rarely observed in smallpox outbreak, it is important to recognize that it may occur under certain circumstances.Proper vaccination of travellers prior to their departure from their native countries and a regular programme for vaccination of medical and hospital personnel could have prevented at least half of the cases which occurred in Europe during the past decade. Although progress in the global smallpox eradication programme has been accompanied by a decreased frequency of importations into Europe, no country should relax its vigilance until smallpox has been eliminated everywhere.

Adolescent↗

Smallpox vaccination for emergency physicians.

On December 13, 2002, President Bush formally announced the national smallpox vaccination program. The plan involves vaccinating health care workers who would respond to possible smallpox cases, including emergency physicians. Although not all aspects of the program are clearly established, it appears that vaccination of health care workers will occur in the near future. This joint statement has been used by the American Academy of Emergency Medicine and the Society for Academic Emergency Medicine regarding smallpox vaccination for emergency physicians.

Adverse Drug Reaction Reporting Systems↗

Detection of smallpox virus DNA by LightCycler PCR.

A 300-bp plasmid fragment of the hemagglutinin gene was used as target DNA to develop a rapid real-time LightCycler (Roche Applied Science, Indianapolis, Ind.) PCR assay for laboratory detection of smallpox virus. PCR primers and probes were designed specifically for detection of smallpox virus DNA, but all viruses of the genus Orthopoxvirus tested could be detected by use of the hemagglutinin gene target sequence. Base pair mismatches in the 204-bp amplicon allowed discrimination of cowpox virus (melting temperature [T(m)], 56.40 degrees C), monkeypox virus (T(m), 56.24 degrees C), and vaccinia virus (T(m), 56.72 degrees C), including the Dryvax vaccine strain, from smallpox virus (T(m), 62.45 degrees C) by melting curve analysis. The analytical sensitivity was 5 to 10 copies of target DNA per sample. The assay was specific for members of the genus Orthopoxvirus; the DNAs of herpes simplex virus and varicella-zoster virus were not detected by the smallpox virus LightCycler PCR.

Animals↗

Following in the footsteps of smallpox: can we achieve the global eradication of measles?

BACKGROUND: Although an effective measles vaccine has been available for almost 40 years, in 2000 there were about 30 million measles infections worldwide and 777,000 measles-related deaths. The history of smallpox suggests that achieving measles eradication depends on several factors; the biological characteristics of the organism; vaccine technology; surveillance and laboratory identification; effective delivery of vaccination programmes and international commitment to eradication. DISCUSSION: Like smallpox, measles virus has several biological characteristics that favour eradication. Humans are the only reservoir for the virus, which causes a visible illness and infection leading to life-long immunity. As the measles virus has only one genetic serotype which is relatively stable over time, the same basic vaccine can be used world-wide. Vaccination provides protection against measles infection for at least 15 years, although efficacy may be reduced due to host factors such as nutritional status. Measles vaccination may also confer other non-specific health benefits leading to reduced mortality. Accurate laboratory identification of measles cases enables enhanced surveillance to support elimination programmes. The "catch-up, keep-up, follow-up" vaccination programme implemented in the Americas has shown that measles elimination is possible using existing technologies. On 17th October 2003 the "Cape Town Measles Declaration" by the World Health Organisation and the United Nations Childrens Fund called on governments to intensify efforts to reduce measles mortality by supporting universal vaccination coverage and the development of more effective vaccination. SUMMARY: Although more difficult than for smallpox, recent experience in the Americas suggests that measles eradication is technically feasible. Growing international support to deliver these programmes means that measles, like smallpox, may very well become a curiosity of history.

Journal Article↗

Pregnancy discovered after smallpox vaccination: Is vaccinia immune globulin appropriate?

Smallpox vaccination just before conception or during pregnancy can result, in rare instances, in fetal vaccinia from viral infection of the fetus. Approximately 50 cases have been documented, despite literally billions of people having been vaccinated. This live viral vaccine has a wider array of rare but serious medical side effects (eg, eczema vaccinatum, progressive vaccinia, encephalitis, myopericarditis) compared with other vaccines that are given currently to the public. In response to recent world events, the Centers for Disease Control and Prevention and the United States Department of Defense established a preoutbreak smallpox vaccination program. Because no actual outbreak has yet occurred, some investigators have proposed prophylactic treatment with vaccinia immune globulin for pregnancies that are exposed to smallpox vaccine to prevent fetal vaccinia. We review the existing medical literature to access the risks of fetal vaccinia in these pregnancies and the controversy regarding the prophylactic use of vaccinia immune globulin.

Counseling↗

Smallpox vaccines: Past, present, and future.

The global eradication of smallpox was a tremendous achievement made possible by the development of an effective vaccine. Routine vaccination of the general population is no longer recommended. However, stocks of variola virus, the causative agent of smallpox, still exist in 2 secure laboratories, and permanent disposal has been controversial. In addition, there is speculation that variola virus may exist outside of these 2 facilities, and there is a concern that the threat of smallpox will be used as a bioterrorist weapon. In 2002, this concern led to a vaccination campaign in US military and civilian healthcare workers and first responders. Although the historical live virus vaccine has proven efficacy, it also is associated with serious adverse events and rare fatal reactions, particularly in the setting of immunodeficiency and atopic eczema. In addition, this vaccine was historically produced using animal intermediaries in a process that was prone to contamination and not acceptable for current manufacturing standards. Development of alternative poxvirus vaccines is focused on replication-defective viruses, gene-based vectors, and subunit approaches to improve safety and immunogenicity. The conundrum is that in the absence of an intentional release of variola, efficacy evaluation of new candidate vaccines will be limited to animal model testing, which creates new challenges for the vaccine licensure process. Although motivated by the threat of bioterrorism, the hope is for new poxvirus vaccines to have their greatest utility against other pathogenic orthopoxviruses such as monkeypox and for the development of recombinant poxvirus-based vectors to treat and prevent other diseases.

Animals↗

Effects of behavioral changes in a smallpox attack model.

The impact of individual and community behavioral changes in response to an outbreak of a disease with high mortality is often not appreciated. Response strategies to a smallpox bioterrorist attack have focused on interventions such as isolation of infectives, contact tracing, quarantine of contacts, ring vaccination, and mass vaccination. We formulate and analyze a mathematical model in which some individuals lower their daily contact activity rates once an epidemic has been identified in a community. Transmission parameters are estimated from data and an expression is derived for the effective reproduction number. We use computer simulations to analyze the effects of behavior change alone and in combination with other control measures. We demonstrate that the spread of the disease is highly sensitive to how rapidly people reduce their contact activity rates and to the precautions that the population takes to reduce the transmission of the disease. Even gradual and mild behavioral changes can have a dramatic impact in slowing an epidemic. When behavioral changes are combined with other interventions, the epidemic is shortened and the number of smallpox cases is reduced. We conclude that for simulations of a smallpox outbreak to be useful, they must consider the impact of behavioral changes. This is especially true if the model predictions are being used to guide public health policy.

Behavior↗

Safety and immunogenicity of IMVAMUNE, a promising candidate as a third generation smallpox vaccine.

A Phase I trial was performed to investigate the safety and immunogenicity of the third generation smallpox vaccine MVA-BN (IMVAMUNE), a highly attenuated clone derived from the Modified Vaccinia Virus Ankara strain 571, in naive and pre-immunized subjects. A total of 86 healthy subjects received the vaccine in five groups using different doses and routes of administration. All 38 subjects seroconverted in the groups receiving the highest dose (10(8) TCID50). All vaccinations were well tolerated with mainly mild or moderate pain at the injection site being the most frequent symptom. The results indicate that MVA-BN has the potential to be developed as an efficient and safe alternative to the conventional smallpox vaccines such as Lister-Elstree or Dryvax. Unique attributes render it a promising candidate for prophylactic mass immunization, even in subjects for whom conventional smallpox vaccines are contraindicated.

Adult↗

Ocular complications of smallpox vaccination.

PURPOSE: To describe the ocular complications of smallpox vaccination and to discuss potential therapeutic options. DESIGN: Review of pertinent medical literature and recent treatment recommendations of the Centers for Disease Control and Prevention. RESULTS: After immunization against smallpox, vaccinia infection of the eyelid, conjunctiva, or ocular surface can result from accidental autoinoculation from a vaccination site before scab formation or from contact with a recently vaccinated individual. While uncommon, corneal involvement can lead to stromal opacification and scarring. Clinical findings of ocular and periocular vaccinia must be differentiated from those produced by other pathogens such as molluscum contagiosum, herpes simplex, varicella zoster, and acanthamoeba infections. Clinical diagnosis can be confirmed by electron microscopy to identify the presence of orthopoxvirus, as well as by virologic culture, polymerase chain reaction, and/or restriction endonuclease analysis of viral isolates. CONCLUSIONS: While the majority of ocular complications of smallpox vaccination in immunocompetent patients are self-limiting, selective cases may require treatment with trifluridine drops, topical corticosteroids and vaccinia immune globulin (VIG). Vaccinia virus does not appear to be sensitive to acyclovir. Specific treatment recommendations are outlined for the spectrum of ocular manifestations.

Centers for Disease Control and Prevention, U.S.↗

Smallpox infections during pregnancy, lessons on pathogenesis from nonpregnant animal models of infection.

Both vaccinated and unvaccinated women during pregnancy who contract variola virus, the causative agent of smallpox, suffer much higher mortality rates than nonpregnants. Furthermore, acute maternal smallpox leads to spontaneous abortion, premature termination of pregnancy and early postnatal infant mortality. The mechanisms governing the abortifacient activity of smallpox, as well as the enhanced susceptibility of gestating women to lethal disease, have remained largely unexamined. Experimental poxvirus infections in nonpregnant small animal models have revealed that T helper type 1 (TH1) cytokines promote efficient resolution of these infections whereas type 2 (TH2) cytokines enhance viral pathogenesis. These data, combined with recent understanding of how the immune system is modulated by pregnancy, may offer important clues as to the increased pathogenesis of variola in pregnant women. The aim of this review is to bring together the current literature on the effects of poxvirus infections in nonpregnant hosts, as well as the effects of pregnancy on the immune system, in order to develop unifying concepts that may provide insight into the pathogenesis of variola during pregnancy and why prior vaccination with vaccinia virus the live anti-variola vaccine offers less protection to pregnant women and their unborn children.

Animals↗