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BEIJING and MANILA, Philippines -- It has been more than two months since the Ministry of Health of China notified WHO and the world about an outbreak of SARS in Beijing and Anhui Province. Since then, WHO experts have been supporting the Chinese authorities in their investigation into the cause of the laboratory-acquired cases, and in
assessing the effectiveness of measures taken to control the outbreak.
On July 1 2004, the Ministry of Health of China released its status report
on the investigation. While the outbreak has now been successfully contained, initial findings from the investigation and the assessment of control measures have raised
several important lessons for global public health.
During the course of the investigation, a significant amount of
information was gathered, although all the practices within the National
Institute of Virology in Beijing have yet to be thoroughly assessed. Although
not all detailed information has been made available to WHO, the following
conclusions have been made about the source of the outbreak:
-- The National Institute of Virology in Beijing was the most likely
source of the outbreak.
-- At least four individuals may have been infected with SARS at the
Institute. These include the two laboratory workers reported in
April, and two additional laboratory workers. These two additional
laboratory workers appear to have suffered from SARS-like illnesses in
early February 2004. Recent laboratory tests performed at a national
reference laboratory were positive for SARS antibodies.
-- The use of inactivated SARS coronavirus, which was not tested to
determine the effectiveness of the inactivation, in a general
laboratory at the Institute appears the most likely cause of the
During the investigation, it became apparent that all the positive laboratory workers worked in the same general laboratory at the Institute. Although no research involving live SARS viruses was known to have taken place in this laboratory, SARS coronavirus that had been inactivated in a Biosafety Level 3 laboratory in the Institute was used on several occasions during the early months of 2004 in experiments carried out in this area. The timing of the use of inactivated SARS coronavirus in the general laboratory coincides with the presence there of all the positive workers and with their likely
WHO recommends that further work is needed to verify the effectiveness of
the method used to inactivate the live SARS virus. At the same time, other
possible explanations of the cause of the outbreak cannot be fully excluded.
The incident at the National Institute of Virology in Beijing has raised
concerns about biosafety in general, and the way in which inactivated viral
material is handled in particular.
''In light of the investigation, WHO believes that Member States should
carefully review biosafety standards and strengthen them to avoid further
incidents,'' said Dr Shigeru Omi, regional director of WHO's Western Pacific
WHO will be working with member states and expert groups to develop
country and regional strategies to strengthen biosafety. Core components of
such biosafety programs at country level are likely to include:
-- A containment policy to reduce the number of laboratories storing and
working on SARS coronavirus.
-- A legislative framework and independent advisory body to assist in
the development, implementation and evaluation of a national biosafety
program and in the investigation of biohazard incidents and the
dissemination of lessons learned to the global scientific community.
-- A laboratory accreditation system based on standardized biosafety
-- An occupational health service to monitor the well being of
Comprehensive biosafety and training programs in all diagnostic and
research institutes supported by a management framework that facilitates
compliance with evidence-based guidelines and the adoption of a positive
WHO also emphasizes that scientists working with highly pathogenic viruses
such as SARS need to handle inactivated material with the utmost caution. In
particular, WHO recommends that:
-- Researchers use appropriate and internationally accepted methods for
validating the inactivation of live viruses.
-- Inactivated material should be handled only in laboratories at
biosafety level (BSL) 2 or above.
-- Researchers handling inactivated material should wear appropriate
personal protective equipment.
-- New methods for inactivation should be adopted only after rigorous
-- Clear and comprehensive protocols should be available for all
In addition to supporting the investigation into the possible source of
the outbreak, WHO has worked with Chinese authorities to evaluate the
effectiveness of the outbreak control measures.
Joint WHO-Ministry of Health teams have visited all the hospitals where
the recent cases were treated before they were admitted to designated SARS
facilities. In addition, WHO experts have reviewed data on contact tracing
and other control measures.
''Overall,'' said Omi, ''WHO believes that the Chinese authorities acted swiftly and effectively to control the outbreak once the alarm had been raised. Extensive contact tracing was undertaken in a matter of hours, and the effective isolation of cases and identification of contacts appears to have ensured that the outbreak was contained with remarkable speed.''
However, there was a delay in detecting the initial cases. As a consequence, two generations of transmission occurred and the application of effective hospital and community control measures took place late in the outbreak. The Ministry of Health of China has acknowledged this and is looking to strengthen further the current detection and response system.
There are a number of lessons from this outbreak that are important
globally, for member states and for WHO itself:
-- Healthcare workers, laboratory workers and people in close contact
with certain animals are at risk of contracting a range of infectious
diseases with outbreak potential. Disease detection systems need to
be designed to take these risk factors, as well as clinical
information, into account -- and to be robust enough to ensure that
nobody slips through the net and evades detection.
-- Healthcare workers need to be aware of the risks associated with
certain occupations (including their own) and to be able to take a
detailed occupational history from a patient.
-- Healthcare workers also need to be aware of the importance of asking
about the health of close contacts of anyone with a potentially
contagious respiratory illness. Quickly identifying possible clusters
of respiratory illness is important in the control of such diseases
and the detection of new or rare infectious diseases.
-- All healthcare workers should be empowered to initiate effective
measures to protect themselves and others from potentially contagious
diseases, in a ''safety first'' approach. This means that healthcare
workers should be aware of potential clinical and epidemiological risk
factors; have ready access to the equipment and knowledge needed to
protect themselves and others; and be allowed to initiate the most
appropriate infection-control measures immediately -- with validation
and approval from senior members of staff later.
This recent outbreak has demonstrated once again that SARS is a
containable disease. WHO commends the Chinese authorities for taking swift
action to control the latest outbreak. WHO will be working closely with the
Chinese authorities to assist in the strengthening of biosafety, and to build
a long-term strategy for strengthening laboratory research and diagnosis in
Source: WHO Western Pacific Regional Office