Infectious diseases experts warned Saturday the world should guard against complacency and maintain surveillance of swine flu and other viruses, and stressed the need for prevention.
While surveillance is important, "prevention really is the thing we have to go for in the future," said Albert Osterhaus, a virologist at the University of Rotterdam in The Netherlands.
Osterhaus was among some 8,000 experts attending the opening day of the 20th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) which runs through Tuesday in Vienna.
The Dutch virologist said he was concerned that since the H1N1/A virus, or swine flu, epidemic has somewhat subsided countries have might let down their guard against spreading viruses.
"My worry is that we have become a little complacent because of this so-called 'wimpy' flu, that we start to forget about the H5N1," referring to the often more dangerous bird flu virus.
In addition, while western Europe has seen H1N1 virus subside, it is still found in eastern Europe, west Africa and certain parts of the United States and will probably resurface in the form of a seasonal flu, Osterhaus added.
He also expressed the need to develop vaccines more quickly to deal with flu outbreaks.
The ECCMID experts warned that seasonal flu in the year after a flu pandemic is generally stronger than in the preceding years because it has been reinforced by new genetic material, and therefore requires national health departments to be more vigilant during flu season.
The swine flu pandemic has claimed the lives of some 16,813 people worldwide since the outbreak of the virus in April 2009, according to the World Health Organisation.
In comparison, seasonal flu kills between 250,000 and 500,000 people each year, the WHO says.