In this issue, Radun et al report a retrospective
investigation of SARS in 21 German guests who stayed at Hotel 'M' in Hong
Kong between 21 February and 3 March 2003 (1). They were able to identify
retrospectively an unrecognized case of SARS in a patient who stayed on
the ninth floor on the night of 21-22 February (the same floor as the
symptomatic physician who had acquired SARS in Guangdong province, China).
The German case who tested positive by serology for the SARS-CoV had developed
symptoms compatible with SARS a few days after returning from Hong Kong.
He had had no direct contact with the index case. However, his companion
at Hotel 'M' did not develop any symptoms and was negative for SARS-CoV
antibodies. Although the main mode of transmission for SARS is close contact
with a symptomatic case, this investigation suggests that transmission
from an environmental source may sometimes occur, and indicates that the
risk of transmission is very heterogenous. It also documents that this
case of SARS was missed by surveillance but fortunately did not result
in transmission.
As we report the results of the European Influenza Surveillance Scheme
(EISS) for the 2002/2003 season in this issue of Eurosurveillance (2),
many European countries have already been affected by the 2003/2004 flu
epidemic (3). The arrival of the 2003/2004 influenza season was anticipated
with more anxiety than usual, due to fear about the re-emergence of SARS,
and in particular, because of the potential difficulty in recognising
any re-emergent SARS cases in the middle of a flu epidemic. Moreover,
the mild influenza seasons seen in recent years have contributed to making
a large population of young children with low immunity who are therefore
more susceptible, and this which might result in an attack rate in children
higher than is usually seen.
Although most of the influenza strains identified so far belong to the
new drift variant A/Fujian/411/2002 (H3N2), for which there is some level
of 'mismatch' with the H3N2-vaccine strain component (4), there is no
available evidence yet of a substantial decreased efficacy of the 2003-2004
season flu vaccine. In France, where the A (H3N2) Fujan-like virus has
been predominant during the current outbreak, data collected by the sentinel
surveillance network (5) suggest a clinical efficacy of the vaccine used
during the 2003-2004 season of 61% (estimated by the indirect method;
A. Flahault, personal communication, December 2003). This season's outbreak,
although quite early, is also in the range of expected morbidity and mortality,
as the following statement of an interim report of the EISS indicates:
'Whilst it is true that there is increased influenza activity in several
countries in Europe, and children (age 0-14, but especially in the age
group 0-4) have been hit harder than in previous seasons with a few deaths
as outcome, there is no reason to think this is an exceptional season,
based on our experience of the past 10 years.' (6)
A study of the national influenza surveillance systems in Europe that
participate in EISS indicates differences, but also reasonable uniformity
in virological data collection methods (6). Although improvements towards
better uniformity have been noticed since the last survey of this kind,
performed in 1996, further harmonisations are still needed, as is the
application of quality assurance for national reference laboratories.
The latter point is important in order to guarantee equivalent timely
detection and typing of new emergent influenza strains in European countries.
The importance of timely detection and typing of influenza strains emerging
in Europe have been well demonstrated in the 2003 A (H7N7) avian influenza
epidemic in the Netherlands (7). The recent report of EISS of the first
isolation a B/Sichuan/379/99-like virus in Germany in week 49/2003, a
virus strain not included in the current influenza vaccine, further demonstrates
the usefulness of timely enhanced virological surveillance (2,8).
SARS has re-emerged on two occasions from laboratories where the SARS-CoV
was being handled. The first case occurred in Singapore in September (9),
while the second was reported on 17 December in Taiwan (10). While there
has been much speculation on the possible re-emergence of SARS in China,
nobody had predicted that the virus would escape so easily from so-called
high security laboratories twice within three months. As the number of
persons exposed to the SARS coronavirus in laboratories that hold the
virus is quite limited, these two events suggest that the risk of SARS
infection among those who handle the virus in laboratories is quite high.
This risk should therefore be taken very seriously. As several European
laboratories hold and work on this virus, there is a likelihood that similar
accidents will occur, and may result in secondary cases and outbreaks.
Therefore, the guidelines for SARS surveillance should include pneumonia
in workers in laboratories that hold the SARS-CoV, as has been included
in the French guidelines (11). National health authorities should also
ensure that the number of laboratories holding the virus remains small,
and that safety levels in these laboratories are fully compliant with
safety standards required for holding such a dangerous organism.
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