STO'B 47

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* * *
The donkey engine coughed and clanked as the engineer, a small, wiry man, ran around it, reaching into its crevasses with a can of oil. “Should have been overhauled,” he muttered to himself, “last time we was in dock.” He put the oil can on the engine and pulled a rag from his pocket, using it to wipe his hands before he ran them through his thinning sandy hair. “Steam is up, sir,” he said at last.

“Very good, Mr Stevens,” said the Captain. Badger was moored in a small bay, with a line running out of her stern gallery to a ruined mole, and another running from her bow to an anchor near the middle of the bay. Chasseur lay between her and the far side of the small bay, with the brigs’ guns commanding the entire seaward approach. Sergeant Harris and his marines guarded the single landward approach to the spring, an overgrown path up some crumbling stone steps, found by the brigs’ boys as they explored the ruined buildings on the small beach. A high stone palisade ringed in the spring and its beach, and apart from the two brigs and their men, cursing and sweating with their barrels of water, the only sound was the cry of several birds, and the occasional ‘ploop’ of a fish breaking the water’s surface.

“On deck,” cried the mainmast lookout.

“Deck, here,” replied the captain.

“Sail in the offing, sir. Looks like a ship.”

“Who is the mainmast lookout?” Philip asked the Master.

“Higgins, sir, able.”

To an able seaman, ship meant a three-masted vessel, with her masts in threes: lower mast, topmast, and topgallant. Some merchentmen sailed ships, though most preferred other rigs, and chances were that the ship was a war ship. The question was, whose?

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STO'B 46

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Some hours later, Dr M’Mullen sat down with Philip for dinner. “Would you consider that to be a bad battle?”

“Oh, no,” said Philip. “Three, no, four dead. Would you care for some wine?”

“Actually, I’d prefer some water if you don’t mind. I’m rather parched after today’s work and the dipper at the scuttlebutt was missing”

Philip put down his glass. “I’m sorry, Doctor, but we’re rationing water in order to reach Gideon’s Bay. I had Wilkins secure the dipper until then.”

“Why not refill at the Roman spring?”

“What Roman Spring?”

“At the old bath, perhaps twelve miles west from the village where we fought.”

“There’s water here? Isn’t it defended?”

“Occasionally the Spanish stop by for water, but not on a permanent basis.”

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STO'B 45

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Some minutes later the officers on the Badger’s quarterdeck moved over to the leeward side as their captain appeared, followed by his guest. In the waist, the sailmaker and his mates were sewing the dead men into their hammocks, in preparation for the funeral. The gunner’s junior mate emerged form the main hatch, bearing a bucket of roundshot for their feet, to carry them down.

Philip led Dr M’Mullen to the taffrail. “The battery commands the harbor,” he explained, “and now that they know who we are there will be no sneaking past them. And, of course, we have to get you to Gideon's Bay.” He paused, but Dr M’Mullen did not take the opportunity to observe that perhaps he didn’t need to get to Gideon’s Bay just yet, far less to observe that Philip should land seamen and marines and take the fort from behind, then burn, sink, take, or destroy all of the shipping in the harbor. Philip sighed. “Mr Horrace,” he said to the gunner, whose watch it was, “once the service is done we will up anchor and lay in a course for Gideon’s Bay.”

Simkin mounted the quarterdeck, flipping through the General Printed Instructions for the funeral service. “Here, sir,” he said.

Captain Fitton took the book from his servant and nodded, saw that the crew was assembled, and pressed his hat more firmly onto his head. He read the service - it mingled strangely with that occurring on the Chasseur, just to windward, and took off his hat as the dead mens’ mess mates lifted the hatch cover, three times, sending the bodies into the water one at a time. The Captain placed his hat back on his head and turned away to wipe a tear from his eye. He glanced over at the Chasseur and saw that they were done (only one splash followed their service). “Mr Horrace, up anchor. Mr Wilkins, signal Chasseur to follow.”

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Why we're asked about eggs when we get the flu shot

When we receive the flu shot (influenza vaccination) we're typically asked a few things, such as are we currently sick, have we ever had Gullian Barre' Syndrome (GBS), and are we allergic to eggs. We're asked if we're sick because the vaccine triggers our immune system, and if we're sick, our immune system is already busy. Depending on how sick we are, perhaps it's better to allow our immune system to finish off our illness before presenting it with the vaccine. We're asked about GBS because having it once suggests that we may get it again. I discuss GBS and the flu vaccine in more detail here. Eggs are my focus on this post, and that explanation requires a little bit of background on how a virus (such as the flu) reproduces (copies itself).

A Little Virology (Study of Viruses)
A cell, whether it's one of the cells in our bodies, or a cell from our pet cat or dog, or whether it is a bacterium (1 bacterium + 1 bacterium = 2 bacteria, and each bacterium is a single cell) contains everything it needs to reporduce. All we need to do is feed the cell, and it does the rest - it repproduces its DNA and all of its internal parts, and then splits into two new cells.

A virus can't do this on its own. It lacks some of the machinery needed to reproduce, and needs to break into a cell and trick the cell's internal machinery into reproducing the virus.

Making the Vaccine - the Chicken Egg Connection
The flu vaccine works by showing a weak or inactivated copy of the flu virus to our immune system, so that if we later see the real flu virus, the immune system can quickly pounce on it and kill it off. As I've said before (see this post for details), the vaccine is kind of like a test prep course for our immune system, where the flu is the actual test: taking the vaccine leaves our immune system better able to take the flu.

The point for this post is that in order to make the vaccine, we need to make a lot of copies of the flu virus, and the easiest way for us to do that is to put the virus in a cell and let the virus do its thing, hijacking the cell and making lots of copies of itself. The cell we use for this is a chicken egg (a chicken egg is a cell).

Since we grow the virus up in a chicken egg, we can end up with some egg in the vaccine itself. So, if someone is allergic to egg, then perhaps the vaccine isn't for them.

The flu

A colleague recently wrote me that he had read my post on the flu vaccine and GBS, and his son had had GBS at age 3.

I am sorry that his son had GBS. It is not a fun condition, and it must be horrifying to see in one's own child. But as a medical professional, and as a public health professional, I have to be very careful not to confuse one patient's experience with what is likely to happen to all, most, or even many patients.

My point on flu vaccine and GBS is that, although there is the possibility of GBS from getting the vaccine, not getting the vaccine leaves people liable to influenza - so the question is, which possibility is greater, and which condition is worse? WHO states that on 1 million vaccinations, 1 case of GBS will result. Last year, (as of 1 July 2008) the US population was 304,059,724(1) - if we had vaccinated everyone, that would translate into 304 cases of GBS; with a fatality rate of 6% (the larger end of the estimate from the CDC, as discussed in the previous post) that would yield 18 deaths total.

On the influenza side, for the 2007 - 2008 season, 88 "Influenza-Associated" pediatric deaths occurred. That's pediatric deaths only - not counting the deaths in young adults, middle aged adults, and the elderly. And this is death from seasonal flu only, not swine flu (also known as H1N1)(2)

So, looking at these numbers, we have 18 vaccination deaths in the entire population, if we vaccinated everyone; or 88 deaths in the pediatric population from the flu itself, plus additional deaths in the adult populations.

I'd rather go with the vaccination.

[Edited 25 October 2009]

Previous post: The flu vaccine and GBS
SOURCE:
(1) http://www.census.gov/popest/states/tables/NST-EST2008-01.xls
(2) http://www.cdc.gov/flu/weekly/weeklyarchives2008-2009/weekly32.htm

The flu vaccine and GBS

In 1976, a study showed a possible connection between influenza vaccination (the flu shot) and Guillain-Barré Syndrome (GBS). In GBS, the body attacks its own nervous system, causing weakness and paralysis. Most people recover completely over several weeks or months, but some do have permanent problems, and about five percent of people who get GBS die. So, a connection between influenza vaccination and GBS alarmed a lot of people (and rightly so) because we don't want to be giving people GBS when we vaccinate them against the flu. Since 1976, many other studies have looked for a connection between influenza vaccination and GBS.(1)

Only one study has found a connection: it stated that for every one million people vaccinated against the flu, one person "may be at risk of GBS associated with the vaccine." Not "will get GBS," but "may be at risk." And again, no other studies have found any connections between the vaccine and GBS.(1) (See also (3))

What this means is that there may have been a real connection between the vaccine and GBS. Unfortunately, we cannot rule this out absolutely. there is a chance - a very small chance, but a chance - that today's vaccine is somehow connected to GBS.

Does this mean that we shouldn't get vaccinated against influenza? Not necessarily. To decide whether or not to get the vaccine, we need to look at what might happen if we do get the shot and compare it to what might happen if we don't get the shot. We've already looked at the biggest potential negative of the shot. The smaller negatives include things like redness at the injection site, soreness, headache, etc, most no different from the results of placebo treatment. For a small group of people there is an additional negative - if you’re allergic to something in the vaccine, the vaccine can give you an allergic reaction. (This is why they ask you if you’re allergic to eggs, for instance, since eggs are used in the preparation of the vaccine).

There have also been concerns regarding vaccines and autism. This originated with the MMR vaccine. Hilton, Hunt and Petticrew, writing in 2007, note that

The aetiology of autism remains unclear. The suggestion that MMR vaccination may be a cause received wide-spread publicity, although subsequent scientific research has failed to support a link.(2)

On a different note, people who get the vaccine sometimes still get the flu - the vaccine matches what the virus looked like when the vaccine was being made, but the virus looks slightly different now. But the vaccine is still useful, since it primes the immune system, and people who get the flu after getting the vaccine have a milder case of the flu - the illness isn’t as bad. So if you’ve ever gotten the vaccine and later gotten sick with influenza, you would have been even sicker without the vaccine.

Next, we need to look at the positives of getting the vaccine, and then the positives and negatives of not getting the vaccine. Then we’ll be able to make an educated decision on whether or not to get the vaccine.

The benefits of the vaccine are that it provides protection from the flu, as I discuss in this post. Some readers may also be aware of the study that showed that people who received a flu shot are less likely to die - from any cause - over the following year, but I suspect that this is because that those who receive a flu shot are also receiving better all-around medical care - I doubt that the flu shot is a panacea (a cure for all ills). So for our discussion, we’ll focus on the flu, which means we need to talk about what the flu actually can do to us.

Next up: the flu
Also: Why do we need a flu shot every year?

Edited 16 Oct, 4:40 pm Eastern)

SOURCES:
(1) Centers for Disease Control and Prevention, “Seasonal Flu and Guillain-Barré Syndrome (GBS)” at http://www.cdc.gov/flu/about/qa/gbs.htm, on 13 October 2009
(2) Hilton, Hunt and Petticrew, “Autism: a Focus Group study: MMR: marginalised, misrepresented and rejected?” Archives of Disease in Childhood. downloaded 21 March 2008 from adc.bmj.com
(3) World Health Organization, "Influenza vaccines: WHO position paper." downloaded form http://www.who.int/entity/wer/2005/wer8033.pdf on 16 October, 2009

The flu shot, and why we need it every year

So, we've said that the immune system can learn to recognize pathogens, and that a vaccine teaches the immune system to recognize a pathogen (If you don't remember how or why, see the previous post.) If that's the case, why do we need a vaccine for the flu every year?

It turns out that the flu virus is prone to mutation. This year's flu virus doesn't quite look like last year's virus. The change is enough that even if the immune system will recognize last year's virus (either from a vaccine or from getting the actual illness), it probably won't recognize this year's flu virus. So even if we got last year's vaccine, we need this year's to be protected this year.

Next: aren’t there problems with the flu vaccine?