2015 Influenza vaccine – 3 strains or 4?February 25th, 2015
The 2014/15 northern hemisphere flu season was unusually severe.
In the US it was the most severe and prolonged for a decade
This may have been partly due to the fact that the yearly flu vaccine that was available was not a good match for the circulating strain.
One factor that determines how well a flu vaccine works is the similarity between the flu viruses used in vaccine production and the flu viruses actually circulating. During seasons when vaccine viruses and circulating influenza viruses are well matched, VE (vaccine effectiveness) between 50 and 60 percent has been observed. H3N2 viruses have been predominant so far this season, but about 70 percent of them have been different or have “drifted” from the H3N2 vaccine virus. This likely accounts for the reduced VE.
Flu viruses change constantly and the drifted H3N2 viruses did not appear until after the vaccine composition for the Northern Hemisphere had been chosen.
The manufacture of the Australian ( Southern hemisphere) vaccine will take this new strain into account
WHO recommends that influenza vaccines for use in the 2015 southern hemisphere influenza season contain the following viruses:
– an A/California/7/2009 (H1N1)pdm09-like virus
– an A/Switzerland/9715293/2013 (H3N2)-like virus
– a B/Phuket/3073/2013-like virus.
The Australian influenza vaccine is available NOW. It would be a very good idea to be vaccinated early to access protection from this new H3N2 strain.
There is also a FOUR strain influenza vaccine ( called Quadrivalent ) being released in Australia this year for the first time – this vaccine covers 4 strains of circulating influenza rather than just 3. This has been developed because the B flu virus has evolved into two different strains, so it has been hard for the vaccine manufacturers to guess which B strain to include in the vaccine – if they could only have one. There is no cross protection between the different B strains so if the vaccine contains ‘the wrong B ‘ the person won’t be protected.
It is very hard to pick which B strain is going to be present in the community, so the vaccine manufacturers developed a vaccine with BOTH of the likely B strains.
The Extra strain in the Quadrivalent vaccine this year is this one ( all the three above plus this extra B )
– B/Brisbane/60/2008-like virus (B/Brisbane/60/2008)
These 4-strain vaccines are the still dead vaccines so the side effects are the same. They have been shown to be safe and to induce antibody protection to both the likely B strains. The quadrivalent vaccine with the extra strain will be a little more expensive as it costs more to manufacture. It is unlikely to be funded on the government free list.
In my opinion, it will be worth having it if you can get it….If you are going to have a jab, better to have one that has more protection from the likely invaders.