2023 marks the 105th anniversary of the 1918 Great Influenza pandemic, a devastating event where over a quarter of the world’s population was infected and as many as 50 million people died. Influenza pandemics are a serious and ever present threat, and the next one could be right around the corner. Since the 1918 pandemic, a further three influenza pandemics have occurred (Asian flu in 1957, Hong Kong flu in 1968, and swine flu in 2009). The question is not if but when will a new virus emerge to transmit from human to human and start spreading. 

Influenza is also a very common seasonal virus. As many as a billion people get the flu every year, with 3 to 5 million cases of severe illness, and about 290,000 to 650,000 deaths due to respiratory disease alone. Although these facts and figures are rather glum, the good news is that we have come a long way from 1918.

So, what are the symptoms of seasonal influenza? Symptoms vary but can include a fever, cough (usually dry), headache, muscle and joint pain, feeling unwell, a sore throat and a runny nose. The cough can be severe and last two or more weeks. Thankfully, most people recover from their fever and other symptoms within a week without requiring medical attention. However, if you haven’t improved after a week or your symptoms are unusually severe, for example you have chest pain or shortness of breath, seek help from a medical professional. Those individuals at higher risk for developing severe disease include pregnant women, children under five, the elderly, individuals with chronic medical conditions and immunosuppressive conditions and those at higher risk of exposure, such as health care workers. Seasonal epidemics occur mainly during winter, which in Geneva would correspond to the months of October to April, peaking from December to February.

The most effective way to prevent the disease is annual vaccination, which anyone can have but WHO recommends; especially to those at higher risk listed above. Safe and effective vaccines have been around for more than 60 years. WHO conducts a vaccination drive every October, which is available to all WHO staff, as well as staff of UNAIDS, ICC, UNITAID, and retired personnel. If you feel you may be in the high-risk category, check with your place of work or local doctor to see if they provide vaccinations. Apart from being inoculated, you can also reduce your risk by doing the same things we did during the COVID-19 pandemic: regularly wash your hands, avoid touching your eyes, nose, and mouth, and avoid contact with sick people. For those who are unwell, cover your nose when coughing or sneezing and self-isolate (to prevent spreading it to others).

The influenza virus was first discovered by Wilson Smith, C.H. Andrewes and P.P. Laidlaw at London’s National Institute for Medical Research (NIMR) in 1933. With support from the US Army, the first flu vaccine was developed by Thomas Francis and Jonas Salk at the University of Michigan. The vaccine was tested for safety and efficacy, before being licensed for wider use in 1945. During the 1947 flu season, researchers discovered that existing vaccines were no longer effective against the flu viruses circulating at the time and needed updating. To investigate the viruses in circulation, the World Health Organization Global Influenza Programme established the Global Influenza Surveillance and Response System (GISRS) in 1952. Initially there were 25 countries who had some form of influenza surveillance in place and were able to report data to WHO, and as of 2023 the network has grown to 132 countries, areas or territories. A total of 160 institutions, including 151 National Influenza Centres, seven WHO Collaborating Centres, four Essential Regulatory Laboratories, and 13 Reference Laboratories are part of the network. Every year, millions of specimens are tested and hundreds of thousands of viruses are exchanged. When COVID-19 came around, it was often the influenza laboratories in the GISRS network that became COVID-19 centers. Through efforts by scientists across the world, it was discovered that influenza viruses constantly evolve into new variants in a process called ‘antigenic drift and shift’. 

To counter this, through GISRS surveillance, WHO has been recommending the inclusion of circulating viruses in annual seasonal vaccines since 1973. Since 1998, GISRS has gone a step further and made biannual recommendations for both the northern and southern hemispheres. The most recent recommendation is for the southern hemisphere flu season starting in April 2024, which was made on 29 September 2023. GISRS operates year round, which enables it to function as a global alert mechanism. Together with the Pandemic Influenza Preparedness Framework, which works to improve and strengthen the sharing of influenza viruses with human pandemic potential and to increase the access of developing countries to vaccines and other pandemic related supplies, WHO is keeping an eye on viruses and supporting countries to be better prepared.

The influenza pandemic of 1918 was one of the worst episodes in history, and joined the bubonic plague outbreak of 1346-1353 (known as the Black Death), the HIV/AIDS pandemic, and most recently, the COVID-19 pandemic. Preventing and managing global outbreaks is a constant process, but protecting yourself and others from seasonal influenza is also important. If you’re in the higher risk categories listed above and living in the northern hemisphere, do not delay getting vaccinated this autumn. It might save your life.