In Australia, swine flu is producing widespread but needless fear. Many of our responses are out of proportion to what is a virus with only low levels of virulence (aggressiveness or nastiness). Currently it causes less serious disease than what we see predictably every year from the spread around the world of seasonal flu strains.

This inappropriate level of fear may paradoxically help spread the virus more quickly. The vast majority of people with this virus only have mild symptoms. Instead of staying at home and recovering, many because they are now unduly worried, seek help and testing in doctors’ surgeries, emergency departments and other clinics. While travelling and waiting in healthcare facilities, they come into contact with many more people than if they had just stayed at home and recovered.

This virus is infectious and will likely cause a pandemic as it spreads worldwide. This does not mean, however, that it will cause the large numbers of deaths seen in 1918/19 that followed the H1N1 Spanish Flu. Indeed this is very unlikely with this strain. The current H1N1 swine flu strain lacks one of the essential characteristics needed to cause that kind of disaster. This strain is no more virulent in people that seasonal influenza — probably less so.

Completely new flu virus strains with new H antigens are a cause of rightful concern. When that occurs there may be little or no pre-existing immunity or protection in the population. Such events with “new” viruses occurred three times in the last 100 years. Firstly with H1 in 1918/19, then H2 in 1950s (Asian flu) and then H3 in late 60s (Hong Kong flu). This swine flu strain is however not a “new” virus, it is just a repackaged H1 strain — variations of which have been re-infecting people yearly since 1918. Thus many of us (if not most over the age of 30) will already have some partial immunity to this new strain. Those of us, who are a bit older, will have more immunity as we are more likely to have been infected infections repeatedly with circulating seasonal H1 flu strains. Both in the US, Canada and in Australia very few older people have been infected, presumably because of pre-existing immunity.

Even though young people are the most likely to have little or no immunity to H1 strains, when infected with this swine flu strain, most infections have been very mild. This again highlights the low virulence of this strain. The US and Canada have had more cases and a longer experience with this virus than we have (the US has probably already had over 100,000 cases). They are now treating it as seasonal influenza. They also have recommendations that appear appropriate for many situations (schools, cruise ships etc), that we should also look at adopting as our public health approach.

Some argue that we need to keep an aggressive response re quarantine, school closures etc, because second and third waves of infection will occur and then there is a high chance that the virus will have mutated to become more virulent — as they saw happened in 1918/19. Despite these frequent statements, this does not appear to have happened in past with influenza. In general the effect with most viruses is that they usually become less aggressive with time not more.

Ten of million of people died during second and third waves after 1918. However this was not due to the direct effect of the flu virus itself but to secondary bacterial lung infections caused nearly all deaths, especially with pneumococcus, streptococcus and staphylococcus. In 1918-19 there were no antibiotics. In the late 1950s when Asian flu struck, many deaths occurred again but this time because penicillin was the only antibiotic widely available and most strains of golden staph had developed resistance.

Antibiotic resistance is a rapidly growing global problem, especially in developing countries. In Australia however we remain much more fortunate with much lower antibiotic resistance rates. We still have a variety of antibiotics (especially injectables) that will work against nearly all strains of bacteria that might cause pneumonia.

We do need to do things to slow the spread of this virus. This includes cough etiquette, and good general hygiene, especially with our hands. This means using alcohol hand rub and soap and water, masks on occasion and other general infection control measures, such as staying at home and away from school and work if you are unwell.

When we have a virus of relatively low virulence such as this strain, we need also to ensure that any new vaccine it is as safe as possible and only given to those where the risks of disease outweigh the risks of the vaccine. This takes time and appropriate very large safety trials. In the 1970s in the US there was great concern when a new form of swine flu developed. A new vaccine was rapidly developed and then given to millions of people. The expected “swine flu” epidemic however never occurred. There was, howeve,r a relatively rare side-effect from the vaccine that lead to an excess (in about 1 per 100,000 vaccine recipients) of Gilluiane-Barre Syndrome – a form of ascending neurological paralysis.

We need to reconsider how we approach this virus. Flu strains every year cause proportionately more illness and deaths than this swine flu strain does no or is likely to do in the future. The implementation of stricter controls via a pandemic plan, should only be adopted when a new influenza strain looks likely to arrive in Australia that is both hyper-virulent and spreads easily. We now know that this is not the case for this swine flu strain as it is not particularly virulent. The approach of the US and Canada, to treat this as seasonal influenza, seems a more appropriate current response while we continue to monitor the situation.

Peter Collignon is Professor, School of Clinical Medicine, Australian National University.