Table: Number of cases* of adverse events after smallpox vaccination among civilians, by type - United States, 24 January - 18 February 2003. (Source: CDC)

* Under investigation or completed as of February 18, 2002; numbers and classifications of adverse events will be updated regularly in MMWR as more information becomes available.

† No cases reported.

§ Events that result in hospitalisation, permanent disability, life threatening illness, or death; these events are associated temporally with smallpox vaccination but have not been documented to be associated causally with vaccination.

¶ Include expected self-limited responses to smallpox vaccination (eg fatigue, headache, pruritis, local reaction at vaccination site, regional lymphadenopathy, lymphangitis, fever, myalgia and chills, and nausea); additional events are associated temporally with smallpox vaccination but have not been documented to be associated causally with vaccination.

In the first stage of the vaccination programme active surveillance is being conducted for potentially life threatening, moderate to severe, and other serious adverse events and for vaccinia transmission to contacts of vaccine recipients. Non-serious events are expected to be under-reported as these are being ascertained through passive surveillance.

In the Netherlands, the ministry of health has written to all local health services asking them to complete contingency plans by April for the mass vaccination against smallpox of the Dutch population of 16 million (2). The Dutch institute of Public Health and the Environment (RIVM) has manufactured 20 million vaccine doses. Supplies of vaccinia specific immunoglobulin from blood donated by vaccinated volunteers are being built up. The mass vaccination option is one part of plans to counter bioterrorism prepared by the National Coordination Centre for Communicable Disease Control (www.infectieziekten.info). Mass vaccination is not the first option, but the Dutch government began preparing for every option after the 11 September attacks in the United States. Ring vaccination remains the starting point for containing an outbreak. If ring vaccination fails or if there are many overlapping rings then mass vaccination could follow.

Plans by the German government to vaccinate selected medical staff against smallpox as a precautionary measure have been objected to by some infectious diseases physicians (3). There is general agreement that vaccination of the entire population should follow within a few days if a smallpox case occurred in Germany. But plans developed by the Robert Koch-Institut (www.rki.de) and government health officials involving vaccination of key medical personnel, health care workers, and other critical personnel before a bioterrorist attack have been criticised, because it is argued that the vaccine is currently unlicenced in Germany and the level of threat does not justify the risks of serious side effects from smallpox vaccination.

It is World Health Organization (WHO) policy that countries should devise and implement plans for the immunisation of key workers to allow a rapid response to a smallpox outbreak (4). WHO advocates investment in public health infrastructure to strengthen outbreak intelligence and verification, support the response to an outbreak, maintain an emergency vaccine reserve, and provide public health information. WHO has been working to provide members states with guidance and help, improving preparedness for epidemics of natural or intentional origin. The organisation's global alert and response programme detects rumours of outbreaks, verifies or refutes such rumours with the affected countries, and rapidly offers technical and operational support through the global outbreak alert and response network (5). Since 2000, investigations by WHO have refuted 13 smallpox rumours (4).