Tips based on evidence from Cochrane
reviews and BMJ’s Clinical Evidence
May 1 2009
Prepared by Tom Jefferson
Graphics by Luca De Fiore
Edgar Hernàndez is second from the right. He is the first symptomatic case of
infection with novel A/H1N1. Edgar lives in La Gloria, Mexico.
You can follow viral spread on Google Maps . Communication technologies play
an important part in surveillance.
Another novelty is Twitter: 2% of messages during the last weekend in April
2009 were on the influenza outbreak with continuous updates for your PC or
The influenza outbreak is caused by a A/H1N1 type. The origin is unknown but
swine flu is a misnomer. Transmission is between humans.
Symptoms are typical of influenza: fever, repiratory symptoms, aches and pains.
There are no bedside tests to differentiate A/H1N1 from other influenza A
The most effective preventive interventions are non-pharmacological.
Avoid travelling to places with high prevalance.
Healthcare workers facing possible cases should wear masks, gloves, gowns,
goggles and wash hands more than 10 times a day. These measures work
against ALL respiratory viruses.
Antiviral drugs will prevent or alleviate symptoms. They should be prescribed by
a physician who will take into account the level of threat. They must be taken
within 48 hours from symptoms developing. This is not easy in everyday
practice. Antivirals should not be taken for prolonged periods.
Points still to be clarified
• What is so unusual about the epidemic?
• Why did the epidemic start in Mexico?
• Is this influenza more virulent than usual?
• Are there co-circulating micro-organisms?
• Which age groups are most affected?
• Free access to Cochrane reviews: