Selecting which flu viruses will go into the vaccine

The flu season coincides with the cold period, for us in the Northern Hemisphere, that’s means November – May, the worst is January-April. We spend more time indoors and in closer proximity to each other – the perfect social situation to share diseases.

The UN World Health Organization (WHO), along with our own Centers for Disease Control (CDC) tracks the worldwide prevalence of every kind of flu all year round. In February, WHO makes recommendations to Public Health Agencies of nations in the Northern Hemisphere. They say “Hey, virus X, Y, Z are really causing some trouble in the world. Here are some strains of the virus. I suggest y’all get to cracking and making some vaccine.”

The US Food and Drug Administration (FDA) gets in on the discussion and they actually decide which strains will be developed and get word (and virus) out to contracted vaccine makers to get the ball rolling. Some manufacturers may already be cooking up early batches, in January, of virus if they have the strain with their fingers crossed that those strains will be selected by the FDA. If so, then they have a jump start.

How long does it take to manufacture seasonal influenza vaccine?

Directly from the CDC website:

"It takes at least six months to produce large quantities of influenza vaccine. For vaccine to be delivered in time for vaccination to begin in October and November (prior to the start of the flu season), manufacturers may begin to grow one or more of the virus strains in January based on their best guess as to what strains are most likely to be included in the vaccine.”

To make the vaccine, the first thing that must be done is to make copies of it – millions of them – which happens in chicken eggs. Next, scientists remove the viruses, purify them – taking away the parts that will make you deathly ill but keeping enough of the virus’ signature elements to mount an immune response in your body. (I’ll discuss the immune system and immune response tomorrow). Stuff the vaccine in syringes or tubes and send them off to the places they are needed.

Companies were well under way making seasonal flu vaccine - to be distributed early August through October - when the first death from the swine flu was confirmed in the US in April 2009. The alarms were raised, and public health officials starting saying out loud, “We might want to be ready for this one. It’s the big, bad virus on the block for the Southern Hemisphere Flu season.” By all accounts, the US acquired the seed stock of the virus this spring, in April/May 2009 and production began immediately. Presumably, they’ve been working overtime to get it done with promises then to supply vaccine in October – which is now, a little shy of the 6 month period reported by CDC.

Vaccine Safety

The Swine Flu Vaccine is made and tested the exact same way our seasonal flu vaccine is made. In fact, had WHO made the recommendation and the FDA had access to a reference strain of the virus, it would have been included in the routine seasonal flu shot. There wouldn’t be a distinction between the varieties. In fact, H1N1 is also the name of the seasonal flu virus in the routine flu shot. They are related viruses, but vaccination against the routine version does not automatically protect you from the swine version. So, in my opinion the Swine Flu Vaccine and the Season Flu vaccine are safe.

Interestingly, many people’s conflict about taking the swine flu vaccine may not materialize. You may come into contact with the virus before vaccine is available. Already, the 2009 H1N1 Virus (Swine flu) is widespread across the US – and this is NOT, repeat, NOT the height of the official flu season for our region. That means people are getting it and dealing with it the old-fashioned way: rest, liquid, volunteer quarantine, and medical intervention ASAP. An updated map of the distribution of the seasonal and H1N1 Flu can be found here.

Moreover, to address the concerns of people who might think that there are boxes of ill-prepared vaccine out there because of the rush job, you can sit down for a moment. The most recent reports indicate that Swine Flu vaccination production is way behind and falling short of the numbers promised by manufacturers. From a scientific literacy point of view, this means that the process is working. There is no rush or by-passing of the approved methods for getting medicine out to people. Yes, I think it would be great to have more, but this all we have for now.

Isn't the real threat the Flu?

Among the general public there seems to be more concern for the vaccine than the strain of the flu itself. From a historical perspective, the flu has been a very important character shaping world events. The widespread use of vaccines has really quieted the flu in recent times. And like the saying, “those who do not know their history are doomed to repeat it”.

I hope not to re-live the lessons of Flu epidemics of the past. Perhaps our society’s less-than-impressed attitude with vaccines is because unlike our grandparents and parents before them, we don’t know what it is like to lose scores of relatives and neighbors from communicable diseases like they did. We don’t know what it’s like for school to be dismissed or factories closed for a disease only to find that when they re-open many of our classmates or work mates are forever gone. People use to drop like flies from the flu and other flu-like illnesses e.g., Spanish flu, Hong Kong flu, Asian flu, yellow fever, and malaria. The 1918 Influenza Pandemic killed more people than World War I. No, we don’t realize how deadly the flu can be and how so many lives can be affected by a disease we think of as just a bad version of the cold. The fact is the success of vaccination in preventing severe epidemics is also its failure in helping people to remember why vaccinations are so important.

References:

Selecting the Viruses in the Seasonal Influenza (Flu) Vaccine
Centers for Disease Control and Prevention, updated August 1, 2009
More information about Swine Flu and Seasonal Flu vaccination production:
How Fast Could a Swine Flu Vaccine Be Produced? TIME, April 2009
Companies starting work on H1N1 vaccine - CDC Reuters, May 2009

More information about Influenza and its impact:
Swine influenza, seasonality, and the northern hemisphere Virology Blog, April 2009
Influenza Pandemics of the 20th Century E.D. Kilbourne, New York Medical College

In my next post I’ll address another concern: “I’ll be fine. I don’t think I need the Swine Flu or Seasonal Flu vaccine.”