The week of September 29^th to October 5^th brought news of progress regarding expanded stockpiles of smallpox vaccine, and new public discussions on pre-event smallpox vaccination.

On Sunday, September 29^th, Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Disease (NIAID), spoke on smallpox vaccination at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy Infectious Disease (ICAAC) in San Diego. He reported the initial data that dilution of the decades-old 80 million doses of frozen smallpox vaccine (Aventis Pasteur) elicited an immune response comparable to that of the 1:5 dilution of the decades-old 15 million doses of lyophilized smallpox vaccine (Wyeth-Ayerst Laboratories). In addition, the frozen vaccine was no more reactogenic, in terms of side effects, than the lyophilized vaccine.

This important news means that there are now enough doses of smallpox vaccine for the entire US population of approximately 285 million because 1:5 dilution of both the lyophilized and frozen vaccines would make more than 400 million total vaccine doses available immediately.

Several ways to provide smallpox vaccination prior to any actual event are under discussion, and on Friday, October 4^th, the various options were presented by three leaders within the Department of Health and Human Services DHHS): Dr. Fauci, Mr. Jerry Hauer, assistant secretary for emergency health preparedness, and Dr. Julie Gerberding, Director, Centers for Disease Control and Prevention (CDC). A final decision will be made by the White House and announced later. A related audio webcast will be available on the CDC website.

One possible option is to arrange for voluntary vaccination of 500,000 health care workers and public health smallpox response teams, followed by up to 10 million health-care workers, police, fire fighters, security people and others who could be involved in the response to a smallpox event.  Subsequently, the vaccine could be made available on a voluntary, non-mandated basis for the general US population, even in the absence of a smallpox outbreak.  

Smallpox vaccine is our least safe vaccine, and it is inevitable that a small number of  significant and occasionally fatal adverse events will occur due to the live-vaccinia virus smallpox vaccine. On October 4^th, the CDC placed on their website (www.bt.cdc.gov/agent/smallpox/vaccine-safety/adverse-events-chart.asp) an additional summary of the major vaccine adverse event rates in the form of a chart. The six adverse events included in the chart are encephalitis, vaccinia necrosum (increased risk in immunocompromised persons), eczema vaccinatum (which can occur in either vaccinees or their contacts who have a history of eczema), generalized vaccinia, accidental autoinoculation (e.g., of the eye), and death.  Based on data from the1960s, before vaccination in the United States ended in 1972, about 15 people per 1 million vaccinated for the first time will have life-threatening adverse events and of these, one or two will die.

The higher numbers today of people with compromised immunity (due to transplantation, cancer, HIV, and other causes), and people with a history of eczema could result in even higher adverse event rates now.  In addition, there are more people today in the United States who have never been vaccinated against smallpox since routine civilian vaccination ended in 1972. Adverse reactions to the vaccine in persons who receive it or who are infected through direct skin contact with vaccines are significantly higher after their primary vaccination.