Restrictions have eased, worldwide borders are open and influenza is again in Australia after a two-year absence.
Immediately, main flu outbreaks are occurring throughout the nation, catching many off guard.
Flu vaccinations goal to guard towards 4 influenza viruses that trigger illness in people (two subtypes from influenza A and two from influenza B).
However vaccine-mediated safety varies annually relying on how nicely the vaccine matches the disease-causing influenza viruses which are circulating at a given time. Vaccine effectiveness – a real-world measure based mostly on the proportion of vaccinated individuals who nonetheless develop the flu – ranges from 16% to 60%.
Nevertheless, it’s nonetheless essential to get your flu shot. If you happen to’ve been vaccinated and nonetheless get the flu, you’re much less more likely to get as sick.
Why it’s troublesome to foretell which subtypes will dominate
Of the 4 sorts of influenza viruses that exist in nature, two trigger important illness in people: influenza A and influenza B.
The 2022 influenza vaccine is quadrivalent (targets 4 distinct viruses): two influenza A viruses (subtypes H3N2 and H1N1) and two influenza B viruses from distinct lineages.
Inside every flu A subtype additional genetic variation can come up, with mutations (referred to as genetic drift) producing many viral variants which are categorised into “clades” and sub-clades.
H3N2 is especially good at producing numerous variety on this means. So predicting precisely which H3N2 virus to focus on within the vaccine is very troublesome.
Ought to I get the 2022 flu vaccine? And the way efficient is it?
A key problem for flu vaccines is the choice for which virus to focus on must be made months forward of time. The the H3N2 virus within the Australian flu vaccine (A/Darwin/9/2021) was chosen in September 2021 to allow the vaccine to be manufactured and distributed in time for the 2022 winter.
There is no such thing as a assure a special H3N2 virus that isn’t so nicely focused by the vaccine received’t arrive within the nation within the months main into winter and begin inflicting illness.
One other issue that has made predicting which H3N2 virus to focus on within the vaccine uniquely troublesome for 2022 is the dearth of information on which viruses have been dominant within the previous flu seasons, each in Australia and on the opposite aspect of the Equator.
With journey restrictions easing in the direction of the tip of 2021, flu instances did begin to reappear throughout the northern hemisphere 2021-22 winter. However the lack of flu instances throughout the previous seasons (on account of COVID) meant the info used to foretell which viruses to focus on was insufficient.
The US Facilities for Illness Management (CDC) analysed knowledge from greater than 3,000 kids and located a vaccine effectiveness of simply 16% safety from delicate to reasonable illness from H3N2. Safety from extra extreme illness was simply 14%.
We don’t know which subtypes will flow into in Australia
Knowledge about flu vaccine effectiveness within the southern hemisphere 2022 winter isn’t but out there, and it’s unclear how protecting the present vaccine is towards the presently circulating disease-causing subtypes.
Whereas H3N2 viruses seems to be driving some illness now, different flu viruses could develop into extra prevalent later within the season.
The flu vaccine is a quadrivalent vaccine, so along with influenza A H3N2, it should shield towards one other influenza A subtype (H1N1) and two distinct lineages of influenza B virus. These viruses don’t change as quickly as H3N2, so it’s extra probably the vaccine will give higher safety towards these different influenza viruses.
Even when vaccine safety towards H3N2 is decrease than normal this 12 months, the vaccine may make the distinction between recovering at residence versus ending up in hospital.
Which flu shot ought to I select? And what are cell-based and ‘adjuvanted’ vaccines?
So who ought to get a flu shot and when?
The flu vaccine provides the best stage of safety within the first three to 4 months months after vaccination. The season usually peaks between June and September – though this 12 months we now have seen a a lot sooner than normal begin to the flu season. It’s unclear whether or not this early begin will imply an extended flu season or an early end. So it’s not too late to get vaccinated.
Flu vaccines are beneficial for everybody aged six months and over, however are notably essential for people who find themselves extra prone to problems from influenza, together with:
Aboriginal and Torres Strait Islander folks aged six months and over
kids aged six months to 5 years
folks aged 65 years or over
folks aged six months or over who’ve medical circumstances that imply they’ve the next danger of getting critical illness.
What in the event you nonetheless get the flu?
If you happen to develop flu signs, isolate and see your GP for an influenza PCR take a look at to find out whether or not you’re certainly contaminated with influenza, notably in the event you’re within the higher-risk teams.
Particular antivirals for influenza might help, if given early. To make sure fast entry to notably weak aged-care residents, aged-care services are being stocked with the flu antiviral drug Tamiflu.
In New South Wales, free drive-through clinics now provide testing for influenza, respiratory syncytial virus (RSV) and SARS-CoV-2, the virus that causes COVID. Different states and territories could observe.
Nathan Bartlett doesn’t work for, seek the advice of, personal shares in or obtain funding from any firm or organisation that might profit from this text, and has disclosed no related affiliations past their tutorial appointment.