GENEVA, 26 OCTOBER - Following the review of
guidance on smallpox vaccination I announced last week, WHO has
consulted with our advisory committee and has updated the official
The conclusion of the review states that:
"Existing vaccines have proven efficacy but
also have a high incidence of adverse side-effects. The risk of
adverse events is sufficiently high that mass vaccination is not
warranted if there is no or little real risk of exposure. Individual
countries that have reason to believe that their people face an
increased risk of smallpox because of deliberate use of the virus are
considering options for increasing their access to vaccines. The
vaccines would be given to people who are at risk of exposure to
smallpox, including health and civil workers, and would be used in a
search and containment exercise should an outbreak occur."
In summary, the guidance is that vaccination of
entire populations is not recommended. The reason for not recommending
such mass vaccination is that there is a risk of severe reactions to
the vaccine, including death, and the fact that vaccination can
prevent smallpox even after exposure to the virus.
Up to now the guidance has also stated that only
those with suspected exposure to smallpox or a related virus should be
vaccinated. That has not changed.
What has changed is the increasing attention being given to the
extent and quality of existing vaccine stocks, and to the possible
need both to stimulate vaccine production and increase stocks of
vaccine for use in the event of an outbreak.
WHO confirms that the best method of stopping a
smallpox outbreak, should it occur, remains the same – search and
containment. That means identifying persons with smallpox, identifying
those people who have been in contact with them, and vaccinating them.
People who have been vaccinated in the past are
unlikely to develop the most serious effects of smallpox.
This advice and background information on smallpox
is now being made available to governments through the WHO website.
Along with this advice we are providing Frequently asked Questions and
Answers about smallpox and a smallpox Fact Sheet with an electronic
slide set of training materials on smallpox. Other information that
will be provided to Health Ministers on request includes a list of
vaccine manufacturers that have the potential to produce smallpox
vaccine and the names of laboratories that can diagnose smallpox. WHO
has also re-established a team of technical experts in smallpox who
are available to assist countries in the investigation and response to
Finally, I want to emphasize that should an
outbreak of smallpox be detected in any country, this should be
considered an international emergency. WHO will help countries to pool
available resources so as to contain the disease as rapidly and
effectively as possible.