Colds are highly common. A young child may get 5–10 colds per year, while adults may get 2–4 colds yearly. About 200 different viruses are thought to cause colds and to date, there is no vaccine. The symptoms of a cold can range from mild to moderately severe.

Flu, on the other hand, affects the nose, throat and sometimes, lungs. Typical symptoms of flu include fever, sore throat, tiredness and muscle aches. In humans, three different types of influenza viruses are known to occur — types A, B and C. Of these, only influenza A and B are associated with major outbreaks and severe phenotype.

Flu vaccines are available. However, flu viruses can be evasive. Thus, the viruses are prone to continuous change or mutation, and unlike most other inoculations, immunity from the vaccine does not last forever. Therefore, yearly vaccinations are recommended for people who may be at risk, including young children, the elderly and people with chronic illnesses or compromised immune system. For most people, flu is a mild illness and does not require medical care as they recover fully within two weeks. However, older people and those with underlying health problems are at greater risk and need to be closely monitored. In such individuals, flu can cause serious complications such as pneumonia and bronchitis that may necessitate hospitalization and may even result in death. In fact, adults over the age of 65 account for 90 percent of flu-related deaths and 60 percent of flu-related hospitalizations according to the Centers for Disease Control and Prevention (CDC). This is because the immune system weakens with age, leaving older adults more vulnerable to the disease.

Treatment for flu is not necessary, but in some cases, the doctor may prescribe an antiviral medication. If taken soon after onset of symptoms, these drugs may shorten the illness by a day or so and help prevent serious complications. It is worth pointing out that antibiotics only work for bacterial infections, and consequently, they are not effective against colds and flu, which are caused by viruses.

A brief history of flu

It has been a century since the devastating 1918-19 flu pandemic. The WHO Global Influenza Surveillance and Response System (GISRS) was established about 70 years ago to monitor and track changes in influenza viruses circulating in the population worldwide and help reduce the impact of such a pandemic and maintain the efficacy of the seasonal influenza vaccines.

The GISRS arose as an integrated scientific and technical global collaboration to fulfil the objectives and activities of the Global Influenza Programme (GIP), initiated in 1947 as one of the first programmes of the WHO. An estimated one billion cases of influenza occur annually, of which 3-5 million are classed as severe, resulting in up to 650,000 deaths. Following the introduction of the first influenza vaccines in 1942 and an appreciation of a need for vaccine components to reflect changes in the circulating viruses, the establishment of the WHO Global Influenza Surveillance Network in 1952 began monitor changes in the viruses in relation to the impact of disease.

Thus, from the outset the global network encompassed surveillance of the epidemiology and impact of influenza, by sharing of viruses isolated by WHO-designated National Influenza Centres (NICs) with Collaborating Centres on influenza (WHO CCs) for antigenic characterisation of the viruses and selection of suitable vaccine viruses, in relation to the manufacture, regulation and administration/distribution of influenza vaccines.

Author: Dr Reshma Ramracheya is a group leader at the University of Oxford with over 18 years of experience in teaching and medical research.

Reference:

• Hay AJ, McCauley JW. The WHO global influenza surveillance and response system (GISRS)—A future perspective. Influenza Other Respi Viruses. 2018;12:551–557. https://doi.org/10.1111/irv.12565.
• Hemila H., Chalker E., Douglas B. The Cochrane Library; 2010.
• Sabbaghi A, Miri SM, Keshavarz M, Zargar M, Ghaemi A. Inactivation methods for whole influenza vaccine production. Rev Med Virol. 2019 Jul 23:e2074. doi: 10.1002/rmv.2074.
• CDC, Centers for Disease Control and Prevention (https://www.cdc.gov/vaccines/pubs/pinkbook/flu.html)
• NICE, National Institute for Health and Care (https://www.nice.org.uk/guidance/conditions-and-diseases/infections/influenza)