But a study by a Japanese government research team has found that patients aged between 10 and 17 who took the anti-viral drug were 54 per cent more likely to exhibit serious abnormal behaviour than those who did not take it.
The team, led by Professor Yoshio Hirota, who teaches at Osaka City University, studied the cases of 10,000 children under 18 who had caught the flu since 2006.
In its final report, released last Saturday, the team wrote: "The link with Tamiflu can't be ruled out... New research should be carried out, focusing on serious abnormal behaviour."
Japan had suspended the use, in principle, of Tamiflu by 10- to 19-year-olds in 2007 after a number of children behaved abnormally after taking it. For instance, one child started to hop and another tried to jump from a balcony.
A probe was ordered that year after a boy who took Tamiflu leapt to his death. But Swiss pharmaceutical giant Roche had been defending its drug since 2006, when the first reports of so-called "Tamiflu suicides" arose in Japan.
Previous analyses had failed to establish a link between the drug and abnormal behaviour.
When the researchers limited their analysis to children who had displayed serious abnormal behaviour that led to injury or death, it found that those who had taken Tamiflu were 25 per cent more likely to behave unusually.
The figure was 54 per cent higher among 10- to 17-year-olds.
However, when taking into account all degrees of abnormal conduct, including minor behavioural problems like incoherent speech, children who took Tamiflu were found to be 38 per cent less likely to behave strangely.
Tamiflu-resistant strains of flu have been on the rise. To prevent a flu pandemic, Singapore is spending about S$50 million to stockpile 1.7 million courses of Tamiflu and 50,000 courses of another drug, Relenza. In total, these vaccines can treat 25 per cent of its population.
