Tag Archives: viral interference

Want to stave off swine flu? Catch a cold

sneezeOK, before anyone says it, the headline is not to be taken as medical advice (I am not a doctor, nor do I play one on television, etc, etc). But research into surprisingly low incidences of swine flu in France in recent months suggests that the common cold may be suppressing the ability of the H1N1 virus to get a toe-hold in our immune systems. [image by trumanlo]

… the percentage of throat swabs from French respiratory illnesses that tested positive for swine flu fell in September, while at the same time rhinovirus, which causes colds, rose […] in late October, rhinovirus fell – at the same time as flu rose. He suspects rhinovirus may have blocked the spread of swine flu via a process called viral interference.

This is thought to occur when one virus blocks another. “We think that when you get one infection, it turns on your antiviral defences, and excludes the other viruses,” says Ab Osterhaus at the University of Rotterdam in the Netherlands.

How important such interference is in viral epidemics is unclear, however: there are also cases in which there is no interference, and people catch two viruses at the same time. Normally, we don’t get a chance to see how rhinovirus affects flu, as flu epidemics usually strike in winter, whereas rhinovirus hits when schools start (late summer in the northern hemisphere).

In other words, the effect isn’t fully understood, or even well enough understood to provide some sort of solution. But it might provide a starting point…

So why hasn’t the US, for example, seen a dip in pandemic cases during a back-to-school rhinovirus outbreak? Mackay speculates that interference from rhinovirus may not be enough to fend off flu if someone is exposed repeatedly. There were far more cases of swine flu in the US in September than in Europe.

The effects of rhinovirus, often dismissed as “only” a cold, are too poorly understood, say all the researchers. Its seeming ability to block swine flu may already have saved lives in France by buying the nation time before the vaccine arrived. It may even lead to a drug that induces the antiviral state, but without the sniffles.

Fight fire with fire, as the old saying goes.