Analyzing the Effects of Swine Flu in the Southern Hemisphere

"We need to be prepared for whatever surprises this capricious new virus delivers next"

Margaret Chan, Director General, World Health Organisation

Winter is drawing to a close in the southern hemisphere and as flu season comes to an end, experts in the northern hemisphere are analyzing the impact of the H1N1 swine flu virus. Government agencies and infectious disease experts in northern countries report primarily good news based on the effects of swine flu in Australia, New Zealand, Chile, Argentina and Uruguay.

At the height of flu season, health care systems in the southern hemisphere were stressed, but managed to handle and recover an increase in patients hospitalized for health problems related to influenza. Experts are calling the H1N1 flu virus pandemic "moderately severe" based on the flu season in the southern hemisphere. The duration of the season was similar in length to average flu seasons, and although swine flu does spread quickly and easily, it's not associated with higher rates of hospitalizations, deaths or health complications than other types of seasonal flu viruses.

Despite high rates of infection, swine flu is a mild disease for the vast majority of the population. Since its outbreak last spring, the virus hasn't changed. It appears to dominate other seasonal flu virus strains, but isn't mixing with any or becoming stronger or more aggressive. While more deaths are being attributed to swine flu than in the past, this reflects a massive increase in infection rates rather than a more deadly virus.

Experts have been able to glean some new information on swine flu based on the recent season in the southern hemisphere. According to the Ministry of Health in Peru, as many as one third of those infected with swine flu have cold-like symptoms without a fever, while others that are infected have no symptoms at all. This indicates that while the virus may spread very easily, many people who acquire it may not even notice. It's also an indication that the infection rate is widely underestimated due to unreported cases.

Although in the past, seniors over the age of 60 weren't believed to be as susceptible to swine flu due to prior exposure to the A(H1N1) virus strains, statistics related to seniors infected in the southern hemisphere are alarming. While fewer seniors may be infected, there is a higher death rate among those who do contract swine flu than was previously realized. Seniors who are infected seem to suffer more complications and be impacted by them more severely.

School age children are most at risk for becoming seriously ill with swine flu, and death rates among infected children are higher than those associated with seasonal flu. Many parents in the northern hemisphere are planning to have their kids vaccinated as soon as possible. Pregnant women, obese people and those with chronic illnesses are all susceptible to higher rates of serious complications from swine flu infection. Experts are recommending those at high risk consider vaccination once it becomes available.

"We cannot say for certain whether the worst is over the worst is yet to come"

Margaret Chan, Director General, World Health Organisation

Despite the relative consistency of the behavior of the H1N1 virus across countries, many flu experts are advising the northern hemisphere to be prepared for surprises. Health care facilities and hospitals should be prepared for the worst, experts warn, so they're truly capable of handling whatever the flu season brings. Based on the experience of hospitals in the Southern Hemisphere, experts warn that ICU (Intensive Care Unit) units in hospitals in particular should be prepared to take on a large number of patients with swine flu complications. The World Health Organisation cites that several countries have reported that nearly 15% of hospitalized cases have required intensive care.

Given that the upcoming flu season in the northern hemisphere represents a second wave of exposure, experts are hopeful that this time around, at least some of the population has already developed immunity. It's also expected that widespread vaccination may curtail the spread of the virus in the north in the coming months. At the very least, it's thought that swine flu isn't likely to have any worse of an impact on the northern hemisphere than it had during the southern hemisphere's flu season.