Daily Bulletin

News

  • Written by Lauren Bloomfield, Lecturer, School of Medical and Health Sciences, Edith Cowan University

Over recent months, reports of “a horror flu season” causing serious illness and death have dominated the headlines.

The high number of cases has led some people to question the effectiveness of the flu vaccine, and whether it’s worth getting if it doesn’t guarantee you won’t get the flu.

The flu vaccine is designed to cover the strains of the flu anticipated to circulate during the season. But even with the most sophisticated scientific processes, determining the right strains to include in the vaccine isn’t 100% foolproof.

Read more: When's the best time to get your flu shot?

Sometimes the virus undergoes major genetic changes or “mutations” in a relatively short space of time. Reports of a “mutant strain” this year means there’s concern some people might catch a strain the vaccine hasn’t protected against.

It’s too soon to tell the full extent of the effects of this mutation on how well the vaccine has worked. But the 2019 vaccine is showing early signs of being a good match for the common strains of the flu circulating this season.

What’s in a name?

Influenza or “flu” isn’t just one virus; different strains circulate each season.

Flu viruses that cause seasonal epidemics in humans fit under one of two major groups: influenza A or B.

The 2019 flu shot isn't perfect – but it's still our best defence against influenza Most flu vaccines protect against four strains of influenza. Image Point Fr/Shutterstock

Influenza A is further broken down into strains or subtypes based on surface proteins called hemagglutinin (H) and neuraminidase (N).

We’re currently concerned about two subtypes which cause outbreaks in humans: A/H1N1pdm09 and A/H3N2.

Influenza B viruses are similarly categorised into strains based on two distinct lineages: B/Yamagata and B/Victoria.

Understanding the circulating strains is important because it gives us clues as to which age groups will likely be worst affected. Influenza A/H3, for example, has historically been associated with higher rates of disease in people aged 65 and over.

But the circulating strains are also important because they inform how the vaccine will be developed. A good match between the vaccine strains and what is circulating will mean the vaccine offers the best possible protection.

So how do we decide which flu strains are covered by the vaccine?

Every year, a new vaccine is produced to cover the strains that are predicted to be circulating in the northern and southern hemispheres. The World Health Organisation (WHO) uses a range of measures to determine which strains should be included in the vaccine.

Many of us who were vaccinated this year would have received a quadrivalent vaccine. This means it covered four strains in total: two strains of influenza A, and two strains of influenza B.

People aged 65 and over are offered a “high-dose” trivalent vaccine, which covers both A strains, and one B strain.

Read more: High-dose, immune-boosting or four-strain? A guide to flu vaccines for over-65s

The Australian Influenza Vaccine Committee (AIVC) reviews the results and makes recommendations for the Australian vaccine, which in 2019 covered the following strains:

  • an A/Michigan/45/2015 (H1N1)pdm09-like virus
  • an A/Switzerland/8060/2017 (H3N2)-like virus
  • a B/Colorado/06/2017-like virus (Victoria lineage) – not included in the trivalent vaccine recommendation
  • a B/Phuket/3073/2013-like virus (Yamagata lineage).

Do we always get it right?

The basic premise of forecasting is that it’s a “best guess”. It’s a highly educated guess, based on analysis and evaluation, but it’s not a guarantee.

The effectiveness of a vaccine depends on a number of factors, only some of which are within our control. While the choice for the vaccine is made on the best evidence available at the time, the viruses circulating in the population undergo changes as they replicate, known as antigenic “drift” and “shift”.

The 2019 flu shot isn't perfect – but it's still our best defence against influenza Flu viruses change every year so researchers have to make an educated guess about which ones might circulate. Image Point Fr/Shutterstock

If the changes are only small, we can still get good cross-protection.

Less frequently, a big genetic “shift” happens. If this occurs after vaccine development has started and the strains have been chosen, we are dealing with a so-called “mutant flu” and the vaccine will likely not be a good match.

So is this year’s vaccine is working?

Data available for this year are showing the majority of influenza cases in Australia have been influenza A – with some states reporting more H3N2 than H1N1, and others reporting a more even mix of both.

The WHO Collaborating Centre in Victoria is also reporting that the majority of specimens of all four strains they’ve tested this year appear to be similar to the vaccine strains.

Read more: We can't predict how bad this year's flu season will be but here's what we know so far

While early indications are that the vaccine has been a good match in the 2019 season, the WHO Collaborating Centre has also recently confirmed there has been a mutation in the A/H3N2 strain this season.

It’s not clear yet if this mutation will have a significant impact on vaccine effectiveness, but it may at least partially explain the high case numbers we’ve seen so far.

Large vaccine effectiveness studies done at the end of the flu season will help assess the impact of this mutation. In the meantime, a mismatch on only one strain means the vaccine will still provide reasonable protection against other circulating strains.

It’s still worth being vaccinated

In the same way wearing a seat belt is no guarantee we won’t be injured in a car accident, a flu vaccine is no guarantee we won’t develop influenza this season.

A person’s underlying susceptibility, due to factors such as their age and health, will also influence how well a vaccine works.

Read more: Kids are more vulnerable to the flu – here's what to look out for this winter

But the flu shot remains a safe and reasonably effective strategy to reduce your risk of serious illness.

While flu epidemics remain complex, advice to prevent flu transmission remains simple. Regularly washing our hands, covering our mouth when we cough or sneeze, and staying home when we’re unwell are things we can all do to help stop the spread.

Authors: Lauren Bloomfield, Lecturer, School of Medical and Health Sciences, Edith Cowan University

Read more http://theconversation.com/the-2019-flu-shot-isnt-perfect-but-its-still-our-best-defence-against-influenza-120088


The Conversation

Politics

Scott Morrison interview with Alan Jones - 2GB

ALAN JONES: The Prime Minister's on the line from Melbourne, Prime Minister good morning. PRIME MINISTER: Good morning Alan ALAN JONES:  thank you for your time. I wish we had three hours but look...

Alan Jones - avatar Alan Jones

Making suicide prevention a national priority

Providing greater support for all Australians needing mental health and suicide prevention services is a key priority of my Government.   Suicide takes far too many Australians, devastating famili...

Scott Morrison - avatar Scott Morrison

Scott Morrison interview with Leigh Sales

LEIGH SALES: Prime Minister, welcome back, and congratulations on your re-election.   PRIME MINISTER: Well, thank you very much, Leigh. It's very good to be back.   SALES: Why is Labor's offer t...

Leigh Sales - avatar Leigh Sales

Business News

5 Types of Deadly Email Accounts In Your Email List And How To Get Rid of Them Quickly

Building a quality email list is a process that will take a fair amount of time. No matter what best practices you follow to collect email addresses there will be always some emails in your list that ...

Ali Burhani - avatar Ali Burhani

Tips for Entering the Solar Power Industry

Perhaps the most interesting statistic about the present-day solar industry lies in the fact that in the United States in 2016, there were more people employed in the solar energy industry than in...

Diana Smith - avatar Diana Smith

How to get the most out of a Premium Graduate Placement

An internship placement from PGP Australia can be a really rewarding and beneficial experience for anyone looking to get their foot in the door in a certain industry like human resources, accounting...

News Company - avatar News Company

Travel

Fun Workouts to Do on a Cruise

With an average of approximately 20 million people cruising each year, cruise vacations are gaining popularity throughout the world. The amount of people that go on a cruise each year is approxima...

Nicholas Rizzo - avatar Nicholas Rizzo

Top 8 Things To See And Do In Australia

Australia - One of the most popular travel destinations in the world, is camping, backpacking, diving, and road trip destination. The country’s immense beauty from Uluru to the Outback, rainforest...

Anna Jay - avatar Anna Jay

8 Tips How to Make Your Travels Memorable

Traveling the world is on every little kid's bucket list, and it usually remains to be there among top three well into the age as well. However, what makes traveling so fun and exciting is the nov...

Diana Smith - avatar Diana Smith

ShowPo