The last time we reported on Swine flu, or 2009 H1N1 virus, the Centers for Disease Control and Prevention was considering whether or not to invest in a vaccine for the new influenza strain.

Now, after several delays, the first batches of vaccines — first, a nasal spray version, then an injectible vaccine — is due to hit hospitals and clinics across the country (and around the world) in the first weeks of October. It's up to each state to decide which groups to prioritize, but pregnant women, young children, and those with certain preexisting conditions such as asthma may be considered priorities. Over the following weeks, the flow of vaccines, produced at five different labs across the country, will steadily increase until, officials hope, any American who chooses to be vaccinated has access to a dose.

To learn more about where to get the vaccine, call: (800) CDC-INFO (800 232-4636) or visit www.cdc.gov/flu.

Here's another good resource for basic H1N1 vaccine info.

In this piece, we profile work taking place at the University of California, San Francisco's Viral Diagnostics and Discovery Center. This lab is home to the ViroChip – a powerful viral diagnostic tool that won its inventor, Joseph DeRisi, a MacArthur "Genius" Grant back in 2004. TheViroChip and other tools are critical to the fight against 2009 H1N1 . Among other things, they may be the first to alert us should the virus mutate into a form that's resistant to the leading antiviral drug, Tamiflu. (Several cases of Tamiflu-resistant 2009 H1N1 have already been reported, but so far they appear to be isolated incidents.)

They'll be looking out for another important mutation too: That's if 2009 H1N1 changes enough so that the current vaccine for it — the one coming out in October — no longer works. (This kind of subtle virus mutation is the reason we need new flu vaccines every year.) So far, this does not seem to be the case.

Listen to the Predicting Swine Flu radio report online.

Animal viruses can be more deadly than their human
counterparts
A lot of people have been commenting about the apparent overreaction of governments to the swine flu.  Why go to such extreme measures to deal with simple influenza?  The reason has to do with the flu pandemic of 1918-1919.

Over those two years, at least three waves of flu struck killing over 600,000 people in the U.S. and a staggering 30-50 million people worldwide.  People died at such a high rate that cities ran out of caskets and dead bodies were stacked on porches and in the streets.

Governments have been concerned that history might repeat itself because the two flues share one thing in common–they both started out as animal viruses.  And our bodies are not particularly good at fighting off viruses new to humans.

Each year a new flock of flu strains kicks off the flu season.  Almost always these strains are variations of human flues from previous years.  What this means is that we have seen cousins of these viruses in the past and so have a leg up on mounting an attack and defeating them.

We do not have this same leg up on animal viruses.  Our immune systems haven't seen anything like them and so can't mount a quick attack.  The end result is that the percentage of people who die from animal flues tends to be much higher than from run of the mill human flues.

In any flu season, the CDC estimates that 5-20% of the U.S. population ends up with the flu.  And that 36,000 of these people die.  The numbers of deaths would be much higher if a truly deadly animal flu virus like the bird flu from a few years back were to emerge and gain the ability to spread from person to person.  (The bird flu was never more than a few isolated cases since it never gained this ability.)

At first blush, this is what the swine flu looked like.  The disease spread easily among people and, in Mexico at least, appeared to be more deadly than normal flues.  So governments around the world sprang into action.  Since flu is spread through contact, governments tried to keep people away from each other.

They closed schools at the fist sign of trouble.  Mexico closed restaurants, theaters and museums too.  All of this was done in an attempt to prevent the spread of a disease like the flu of 1918.

At least outside of Mexico, this flu does not seem to be too much worse than other flues.  So it may be that governments overreacted this time.  But I would prefer that they overreact like this as opposed to ignoring a deadly pandemic.  We don't want another 1918 on our hands.

More info on The 1918 Flu in San Francisco

The swine flu virus. Credit: C. S. Goldsmith and A. Balish, CDC.

As this story is being produced, the reports on swine flu are changing hourly. Cases are popping up closer and closer to home, and the CDC is updating several times a day on the spread of the virus, and plans to fight it.

The $64,000 question is how worried we should be.

Swine flu is largely untreatable: The two effective antiviral drugs, Tamiflu and Relenza, must be taken within 48 hours of infection to stop the spread of the virus.

That leaves a vaccine. Vaccines are relatively straightforward to create, but they take time. If swine flu becomes a deadly pandemic (meaning it's not only widespread — a pandemic – but more lethal than it appears to be so far) the demand for vaccines would likely far outpace supply. According to Art Reingold, at UC Berkeley's School of Public Health, it could take years for doses to reach everyone in the world who's vulnerable to the disease. Here in the US, we have very few vaccine producing facilities, which means we'd be competing with other countries' priorities to treat their own citizens.

Our story focuses on what could, one day, be the answer to pandemics like this one: a universal vaccine. Scientists like Harvard Medical School's Wayne Marasco believe that, in just a few years, we might be able to inoculate ourselves against nearly all influenza viruses – like a tetanus shot, against the flu. Universal vaccines will come too late for our current swine flu pandemic. But they may well be our response to pandemics of the future.

Listen to the Swine Flu and You radio report online.