The most effective vaccination strategy to use in the event of an outbreak is a matter of continued debate. However consensus is developing that, if an outbreak is identified early enough, ring vaccination is likely to be most effective.
Ring vaccination - vaccinating only the close contacts of infected individuals - was used effectively to control outbreaks during the eradication programme. Cases must be identified quickly and, in addition to vaccination of close contacts, the patients must be isolated and quarantined to reduce the spread of the disease. Current WHO guidelines support the policy of ring vaccination with containment and isolation. In line with these guidelines, EU Member States have indicated that they support a ring vaccination policy. That said many countries have also included in their preparedness plans the option to move to mass vaccination if attempts to control an outbreak with ring vaccination should fail.
The link between stockpile size and vaccination policy is less clear. It was acknowledged in a recent EU Commission report that 'a national stockpile providing total coverage for the population does not necessarily imply a mass vaccination policy. It may reflect a political decision to provide reassurance to the population and to be able to respond to anticipated public demand.'
The policy of stockpiling smallpox vaccine has international support. The WHO has produced guidance recommending that countries stockpile smallpox vaccine and it has stated its intent to build a global stockpile of 200m doses of vaccine. Several countries in North America and Asia have announced that they are stockpiling vaccine. In addition, most EU Member States have, or are acquiring, stockpiles of smallpox vaccines. A few of these countries have ordered or are planning to order new, second-generation vaccines.
As regards the size of vaccine stockpiles, it is known that the US has stockpiled one dose per citizen of the new, second generation vaccine, ACAM2000. Within the EU the size of the national stockpiles, in relation to the national population, ranges from enough to provide one dose per citizen to enough for one citizen in thirty.