Prof Marietjie Venter, an extraordinary professor in UP’s Department of Medical Virology, explains the origins of swine flu and how we can prevent its spread.

“Swine flu is the H1N1 2009 influenza virus that caused the 2009 pandemic, so it’s been circulating for the past 14 years,” explains Professor Marietjie Venter, an  extraordinary professor in the University of Pretoria’s (UP) Department of Medical Virology.

It was called swine flu, she says, because it emerged in 2009 among pigs in Mexico and in the US, and was a new strain that had reassorted between pig, bird and human influenza strains, and could then infect humans. It caused the pandemic because no one had come across it before. Today, it is just the seasonal flu, and it occurs every couple of years. 

“It causes flu-like symptoms such as a cough, body aches, fever and congestion in the respiratory tract,” Prof Venter says. “Sometimes, it can cause more severe disease such as pneumonia and even death, but most people will experience mild disease. High-risk patients include pregnant women, young children, patients over 65 and those with underlying conditions such as heart and lung disease or immunosuppression.” 

These individuals can experience very severe disease and should be vaccinated before flu season. However, people of all ages can benefit from the vaccine to avoid getting sick or infecting others. 

Swine or H1N1 influenza circulates around the same time as other influenza viruses – usually between May and September in South Africa or in late autumn through winter. During winter, influenza accounts for up to 70% of respiratory infections. During the COVID-19 pandemic, there were almost no cases of influenza, probably because of travel restrictions and mask-wearing, both of which halted the introduction and spread of the virus in South Africa.

“It’s likely that people now have little immunity, and those that don’t get vaccinated experience more severe disease and larger epidemics occur,” Prof Venter says.

Influenza is very contagious and is spread through droplets from coughing and sneezing. The best way to prevent swine flu is to get the influenza vaccine.

“The vaccine is updated every year by the World Health Organisation for the northern and southern hemispheres, using information on influenza strains circulating worldwide,” Prof Venter explains. “The vaccine contains recent variants of the 2009 H1N1 virus, Influenza H3N2 and Influenza B, and protects against infection and severe disease if you get the jab before the season starts. It’s not too late to get it now, but you need two weeks to become immune, so it’s best to get the vaccine by April, before the influenza season starts.”

Influenza is cleared from the body within 10 days and patients are contagious in the first seven days of showing symptoms. Most people will recover fully in this time, but in severe cases, they may remain sick for much longer.

H1N1 and other influenza subtypes can be treated with an anti-viral called Tami-flu, but it is only effective if taken in the first two days of the appearance of symptoms, or as a prophylaxis shortly after exposure in high-risk patients. 

“To protect yourself against infection, frequent handwashing is recommended, as is wearing a mask around sick people,” Prof Venter advises. “Sick people should also wear masks to avoid infecting others.”