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More Than 100,000 Troops Receive Smallpox Vaccination

Kate Traynor

Early feedback from the Department of Defense (DoD) smallpox vaccination plan indicates that the inoculation program is proceeding smoothly and has resulted in fewer adverse events than expected.

“Since the middle of December, we have vaccinated well over 8,000 health care workers ... [and] well over 100,000 combat personnel,” said Colonel John D. Grabenstein, the pharmacist who serves as deputy director for military vaccines in the Army Surgeon General’s office. Grabenstein, speaking at a February 13 public forum sponsored by the Institute of Medicine in Washington, D.C., described the military’s smallpox vaccination program as having “well over 100,000 successes.”

The first stage of DoD’s program, which Grabenstein referred to as a “do-and-learn exercise,” has been the vaccination, started last December, of up to 5,000 members of the military’s smallpox-epidemic response teams. Vaccination of 10,000–25,000 members of hospital- and clinic-based medical teams and 500,000 combat forces began in early January. All vaccinations are done with Wyeth Laboratories Inc.’s recently relicensed Dryvax vaccine, which contains live vaccinia virus.

Vaccinees Tracked by 3 Systems

The Centers for Disease Control and Prevention (CDC) collects data using three separate but related systems for tracking information about smallpox vaccine recipients and their reactions to the vaccine. 

Hospital Smallpox Vaccination Monitoring System (HSVMS). This Web-based portion of CDC’s smallpox vaccination program is designed to provide real-time monitoring and tracking of health care workers who receive smallpox vaccine. According to CDC, HSVMS is the only part of the agency’s smallpox vaccine program that monitors daily care of the vaccination site and tracks the number of workdays health care workers miss after being vaccinated. Vaccination clinics are asked to examine vaccinees daily for three to four weeks and report specific postvaccination information to HSVMS. CDC plans to use HSVMS data to assess vaccination-site care and adverse events among vaccinees, and health departments will be able to view and generate reports from their own HSVMS data. 

Pre-Event Vaccination System (PVS). This Web-based data-exchange system is designed to collect information on smallpox vaccinees. Using PVS data entered by smallpox-vaccine-clinic staff, CDC will monitor emergency-preparedness activities by running aggregate reports on the total number of vaccinees. CDC will also use PVS to track vaccine use, vaccination success rates, adverse events, and other information. States, local jurisdictions, and clinics can create reports using their own PVS data only. 

Vaccine Adverse Event Reporting System (VAERS). VAERS, a postmarketing safety surveillance program, is jointly operated by CDC and FDA. The system was created to collected information about adverse events that occur after the administration of any licensed vaccine, not just the smallpox vaccine. CDC has asked that all serious events related to smallpox vaccination be reported to VAERS. Data can be entered into VAERS over the Internet or sent in by mail.

In describing adverse events among vaccinees, Grabenstein said that “just about everything ... is occurring at rates less than would historically be predicted.” He attributed DoD’s avoidance of undue complications to a strong education effort and military personnel’s healthy respect for the vaccine’s dangers. 

Reactions to the vaccine do occur, but they are mostly temporary, minor, and expected, Grabenstein said. None of the patients suffering from vaccine-related complications have required treatment with vaccinia immunoglobulin, and no deaths have been reported among vaccinees.

“We’re seeing tens of thousands of people with pustules at their vaccination site,” Grabenstein noted. “We’re seeing people with fever and rash and malaise and swollen lymph nodes, just like you would expect from all of the historical data.” Overall, 3% of those who were inoculated—or 4–5% of primary vaccinees and 1–2% of those who were previously vaccinated against smallpox—have required at least one day of sick leave. These soldiers have missed a day and a half of work on average, according to DoD.

Among vaccinated hospital workers, Grabenstein said, “health care continues as normal, with recently vaccinated staff ... relying on the key principles of infection control,” such as proper hand hygiene and a full-coverage bandage on the inoculation site, to prevent inadvertent transfer of the potentially debilitating vaccinia virus.

Only one case of autoinoculation, or transfer of virus from the inoculation site to another region of the vaccinee’s body, has occurred among military vaccine recipients, Grabenstein said. According to the Centers for Disease Control and Prevention (CDC), about 530 cases of auto-inoculation, often to the eye, are expected per million vaccinees.

One of the most serious complications of smallpox vaccination is encephalitis, which CDC said has historically affected about 12 of every 1 million vaccinees. DoD has reported two cases of apparent vaccine-induced encephalitis among military vaccinees. Grabenstein said that both soldiers—one a primary vaccinee and one a revaccinee—required short hospital stays but have fully recovered from their illness and are back at work.

Another serious but rare adverse event, myocarditis, was diagnosed in a first-time vaccine recipient. Grabenstein said that this soldier spent two days in the hospital, recovered fully, and has returned to duty.

Grabenstein described “a rash of rashes” among smallpox vaccine recipients. “We are seeing probably something on the order of a dozen per thousand or so folks with flat rashes,” he said. “They are treated symptomatically as outpatients and sent back to work.”

In only seven cases, Grabenstein said, has DoD determined that a rash met the criteria for generalized vaccinia, a complication that CDC expects to arise in about 240 of every 1 million vaccinees. All seven soldiers, Grabenstein said, were treated as outpatients and are back on the job.

Grabenstein noted that categorizing rashes on recent smallpox vaccinees is a learning process for health care workers. At first, he said, even flat rashes among otherwise asymptomatic patients tend to alarm clinicians, who wrongly conclude that the patient has generalized vaccinia. Over time, Grabenstein said, clinicians learn to look for vaccinia-specific symptoms, such as vacuoles and pustules, before becoming alarmed about a rash.

CDC recently published an illustrated guidance document for clinicians that describes the diagnosis and treatment of adverse reactions associated with the smallpox vaccine.1 Most of the expected reactions are described in the document as self-limiting and include fever, headache, chills, local skin reactions, nonspecific rashes, erythema multiforme, and vaccination-site pain.

According to CDC, the use of vaccinia immunoglobulin (VIG) is reserved for severe cases of inadvertent inoculation, severe generalized vaccinia, eczema vaccinatum, and progressive vaccinia. VIG is available from CDC under an investigational new drug protocol. The agency also maintains a supply of the antiviral drug cidofovir for use as a second-line treatment in patients who do not respond to VIG.

Although DoD’s initial evaluations indicate that the smallpox vaccination program is succeeding, Grabenstein noted that important data about the project still need to be analyzed.

“When we get down the road a little bit,” he said, “we will be able to harness all of our automated databases of outpatient visits and inpatient visits and get ... precise data on the medical encounter level. And then we have surveys that have been received but not yet processed that get at the symptom level—fever, malaise, swollen glands that might or might not have [generated] a clinic visit.”

  1. Centers for Disease Control and Prevention. Smallpox vaccination and adverse reactions: guidance for clinicians. MMWR Dispatch. 2003; 52:1-29.