You find me just returned from a trip to another medieval theocracy where this site is banned – but this is a state that takes its collective delusions so seriously they scan all your baggage on the way in to make sure you’re not trying to sneak any booze in. Or pork. Because it’s unclean. But you wipe your arse with your hand, obvs…
Anyway, while I was incommunicado there has been some seriously ill-informed reporting about the current flu vaccine (and a number of other subjects that I’ll get to later), all of which have had me ranting at anyone who would listen. Which was, well, no-one given the appalling state of my Arabic.
I’ve got myself into trouble writing about flu before when I inadvertently trashed a BMJ paper 5 years in the making in about 500 words. Ooops. This time the Daily Mail and Daily Telegraph – both of whom have impeccable track records when it comes to seriously shit science reporting – have claimed the current vaccine is about as much use as tits on a nun due to it being “only 3% effective“. They are not alone. The BBC falls into the same trap plus some areas of the media are blaming the government. All this is based on either misinterpretation of a recent paper or just sheer laziness by journalists who simply can’t be arsed reading to the end of a publication – or are too dense to understand that on which they report. .
Yes, the report does suggest in its abstract that early data suggest the current seasonal flu vaccine is only ~3% protective against the main circulating strain – A(H3N2) – in adults, but it also shows it can still protect against other strains. But you wouldn’t believe this if you read the newspapers who get it so egregiously wrong. The finding that it does give a degree of protection confirms the findings of another recent paper which shows the specific response against A(H3N2) might not so good but the immune system will still produce antibodies that are broadly cross-reactive when a particular season’s vaccine isn’t such a great match to the circulating strains.
The recent coverage also ignores that a different version of the flu vaccine – a nasal spray designed for vulnerable children – is also available and is working (again you’d know this if you’d read the sodding paper). Which is important; the average attack rate for ‘flu in kids in any season is 12-15% compared with 3-4% in adults. This is for a number of reasons, but discouraging parents of vulnerable children from getting them vaccinated will increase the risk of serious childhood illnesses (not just flu), hospitalisation and death.
So, there is still benefit from getting the flu vaccine even in years when the strains in the vaccine are a poor match for the circulating strains. And you can’t get flu from the jab, it’s a killed vaccine. You might get a sore arm but that’s about it.
So What’s Gone Wrong?
OK. Influenza virus is an RNA virus and when it replicates it lacks the self-correction mechanisms inherent in the DNA copying process, so it mutates lots. Like really lots. This inaccurate copying means the precise makeup of each strain knocking about at the end of a season is often different to that found at the beginning, and the main A(H3N2) strain knocking about this season has ‘drifted’ – as we say in the biz – since the vaccine components were specified. And for reasons explained below, what goes into the vaccine needs to be decided well in advance – and sometimes we bet on the wrong horses.
This year the drift in flu virus antigens over the season has made the vaccine far less effective than usual against one of the principal strains knocking about – so the specific response against A(H3N2) is not so good but the immune system will still produce antibodies that are broadly cross-reactive – so just because the main current strain isn’t a good match to the vaccine that doesn’t make the vaccine useless. Far from it. It still protects against influenza B, the avian strains and some other H3s, in addition to eliciting the cross-reactive antibodies as described above. The authors of the original paper make this clear – if only the journalists could be arsed reading it:
The upper 95% CI of 35% shows we can be confident that VE is low at this point although we cannot be clear that influenza vaccine has no effectiveness this season. Indeed the significantly lower influenza positivity in areas where children of school age were vaccinated compared to non-pilot areas… is suggestive of a possible impact of the childhood influenza vaccination programme.
Furthermore, this mid-season analysis does not preclude the likelihood that the vaccine should offer protection from different types of influenza, such as influenza B that may still circulate later in the season. All these elements will form part of the end-of-season analysis including stratification by age-group and scheme.
So while this vaccine may not elicit specific neutralising antibodies against the drifted A(H3N2) strain it will still be partially protective a- nd add to our individual ability to deal with flu virus we’ve built up over many flu seasons. (This is one of the reasons attack rates are so much higher in kids: the adult immune system remembers many different seasonal strains from years past).
On a point of pedantry remember I’m not talking about ‘man flu’ or the casual use of the word when applied to a trivial case of the sniffles. I’m talking about the influenza virus. The one that puts you in bed for a week, makes you feel like someone has taken a cricket bat to every muscle in your body and you’re on the verge of coughing up your kidneys. That’s if you’re lucky. If it doesn’t kill you. ‘Proper’ flu is serious.
In the 500 years it’s been with us it’s preferentially killed the old, the young, the infirm, the obese and the pregnant, but it kills the healthy too by making other conditions worse and indirectly via acute secondary infections, increasing risk of vascular events like stroke and heart attack and by worsening underlying diseases like congestive heart failure and chronic bronchitis.
The 2009 H1N1 killed in excess of 250,000 but we dodged the bullet: the 1918/19 H1N1 killed more people than both World Wars combined in a single season. It killed more people in 24 months than AIDS killed in 24 years and more in a year than the Black Death did in a century. Over a quarter of patients who caught (A)H1N1 in hospital died from it. And the current vaccine is protective against it.
How Influenza Vaccines Are Specified
This is why the flu vaccine production window is limited and complex with little room for slippage in the process.
Flu vaccine manufacture and supply is undertaken on a global basis. Eight international companies manufacture flu vaccines for the UK. They all also supply other European countries and some manufacture vaccine for North America as well.
The WHO makes recommendations on the composition of the northern hemisphere flu vaccine in February. Their recommendations are based on the flu virus strains that they judge to be the most likely to circulate the following winter, and take into account data from the southern hemisphere flu season. Production of the vaccine usually runs from March to August / September, and packaging and labelling can continue until October.
Manufacturers make an overall decision on their flu vaccine production quantities based on expected demand from all the countries that they supply. Such estimates will be based on a number of factors, such as current quantities supplied; anticipated changes in vaccine recommendations in different countries; and other commercial decisions regarding market share.
Based on this information, the manufacturers start their planning cycle, which includes reviewing existing production capacity and the possible need for expansion; ordering sufficient pathogen-free eggs to meet production needs; and filling, packaging and labelling needs. This planning cycle starts 18 months before a flu vaccination programme. The flu vaccine production ‘window’ is limited.
Once vaccine composition is agreed the manufacturers have to grow the vaccine viruses, formulate the vaccine, test, license, and package and supply the vaccine within six months in order to ensure stocks are available in time. And each individual dose is made in a chicken and harvested from an egg.
That’s a lot of eggs…