“Discuss the effectiveness of the flu vaccines including cost, prevention rate and at risk groups.”

“Beat flu before it beats you!”

(NHS Wales, 2018)

Doctors’ surgeries are full of posters urging patients to protect themselves with the seasonal influenza vaccination. Last year a record 14 million people in England and over 800,000 people in Wales were vaccinated (Vaccine Knowledge project, 2018; Public Health Wales, 2018) yet the number of influenza cases reported was at its highest since the 2009 pandemic (Public Health Wales, 2018). Behind the slogans, questions remain about the efficacy of the influenza vaccinations.

Influenza is “an acute systemic viral infection that primarily affects the respiratory tract” (Walker et al, p.319). Seasonal influenza occurs in the winter months in temperate climates. Four different seasonal influenza virus groupings are cited, A, B, C and D – each consisting of “seven or eight RNA segments enclosed in an envelope of proteins” (History of vaccines, 2018). As influenza D is not contractable by humans and influenza C “causes milder infections”(WHO, 2014), only influenza A and B are part of vaccination programmes in the UK.

Variations in the haemagglutinin (H) and neuraminidase (N) glycoproteins on the surface of the virus (Walker et al, p.319 result in antigenic drift as the strain mutates from the ancestor strain. The host may not always recognise the new mutated virus and antibodies to previous strains are not effective. (History of vaccines, 2018). Influenza B can only mutate by antigenic drift so its viral evolution is more gradual (CDC 2018, Nobushawa and Katushiko 2006). However, influenza A is also capable of antigenic shift when two or more strains combine, resulting in a virus with a different H or N type to the ancestor strain ie AH2N3. Influenza A is unique as it infects a wide variety of animals as well as humans (History of vaccines, 2018). Antigenic shift occurs when an influenza A virus is transmitted to another animal and mutation happens within the host. The spread of the new strain is determined by the ease with which it can transmitted from human to human. By contrast, influenza B is divided into strains alone, for example, in the 2017/2018 season, influenza B/Yamagata was noted as being the dominant B strain across Europe (NHS Wales, 2018)