Investigation into China's Recent SARS Outbreak Yields Important Lessons for Global Public Health


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

incubation periods.


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

        laboratory workers.


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

biosafety culture.


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

        inactivation techniques.


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



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