At the barricade where Frank becomes infected, the soldiers have clearly been watching, camouflaged, the whole time. So why do they wait to show themselves until after he becomes an infectee? Perhaps so that there's less resistance when their plans for Selena and Hannah are revealed?
They're waiting to kidnap the women.
At the beginning of the film, Jim learns of the infected and falls under mortal peril because he kept yelling 'HELLO!'". But at the end, he and the girls are again using the word HELLO as an SOS message for pilots. This symmetry underlines the fact that, despite all the despair and trauma the story inflicts on him, his human spirit and hope endures.
It's shown repeatedly that the time from infection to Rage is never more than a minute or so. That should make detecting and isolating the infected pretty easy. This is the reason most real viruses have an incubation period.
In theory, but the infected do nothing but attack attack attack in a blind rage, and if they get so much as a drop of blood or saliva into an open wound (pretty easy to do in a fistfight), you're done. Now there's two of them attacking the next person. And then three attacking the person after that.
There's also the ever-so-common mistake of calling a virus an infection, when viruses and infections are completely different.
It also explains why the virus was contained in Britain. With practically no incubation time, there is (virtually) nil chance of infected people getting through the ports and airports undetected. With Britain being an island, they'd have to walk through the water or something!
The Channel Tunnel is preferable. Though either the British or the French would probably have done something to prevent this too.
Yeah, that probably would have been great.
Viruses of that sort normally end in the death of the infectee. The Rage virus leaves them alive to continue to spread the virus until their death, presumably. In real life, there have been cases where viruses and/or diseases become more deadly in higher population densities. A smaller population density would by necessity have the virus reproduce slower or have a larger incubation period or it would die out without spreading itself. In a larger population density, the virus can be allowed to kill as quickly as it can so it can spread to as many as possible before the host dies.
After 28 days, the infection should have largely died out. Given that the Infected neither eat nor drink, and that they seem to barf up copious quantities of blood, their lifespan would realistically be mere days. Some of them are seen to rest (the ones Jim first encounters in the church), but still, there really shouldn't be that many left after a month.
The infection has largely died out. That's how Jim is able to walk through London, a city of several million people, yelling "Hello!" very loudly without being mauled in the first ten seconds. But there are still some more recent infectees hanging around.
The movie doesn't explicitly state that the infected in the movie have been around for twenty eight days. That is only when the infection began. The infected that we have been shown might as well have been people infected after the initial plague. There aren't many left during the film, and the ones we see are probably those infected later on. The original infectees would have died out days if not weeks earlier.
Or they conserve strength by simply sleeping all the time unless a victim is around, and they might eat corpses and drink water off screen or something.
"The answer to infection" involves waiting for the Infected to starve to death, something that would be impossible if they did eat and drink off screen. Furthermore, they are seen lying on the ground, dying of starvation close to the end of the movie.
The infected are perfectly capable of starving to death, no matter how much they may eat. As they explicitly said in the film, they don't work or farm. There's only so much food to go around before it runs out and/or spoils. When the easily accessible food sources run out, there's nothing for the infected to turn, and they just starve to death.
If the Rage Plague causes people to be mindlessly hostile and violent to other people, why aren't the Infected attacking each other?
A supplementary comic claims they are attracted to chemical scents like soap. Not sure how much sense that makes, but whatever. Also, a virus like that wouldn't gain anything from having its host attack other infected hosts.
It's an artificial virus, it doesn't have to behave like a natural one. As for why they don't attack each other one guess might be some sort of chemical Rage victims give off? Just a guess.
Maybe the Virus was having its intended effect (Of mellowing them out and making them all peace loving hippies) ... But ONLY to others that are infected? To them, they are merely spreading the love, so to speak.
So, they're keeping the Rage-infected soldier alive to see how long it takes for them to starve. Okay. You can't break his legs and arms or even just cut them off? You're putting a lot of faith in that chain...
Well, no, you can't. They're living people, not zombies. Cutting off their arms would make them quickly bleed to death and breaking the limbs and leaving them that way could lead to infection, internal bleeding or maybe even something else screwed up because of the marrow. They want it to die of starvation, after all.
Jim wakes up in a hospital bed after 28 days with an IV in his arm... but no catheter. So where does all that fluid that's been dripping into him go?
It's generally implied that most of London's population have become infected or are now dead, possibly both. This is relatively straight forward, yet London is a city of 7 to 8 million people, where did all the bodies go? Let alone in the rest of the country.
How about the scene when main character are leaving the London and Jim watches piled up bodies next to bulldozer, indicating that before total collapse of public order, some actions were taken?
A great deal of people managed to escape the country. A great deal more dispersed into the countryside before getting killed or infected.
Or maybe they're all holed up in their apartments, refusing to let any other survivors know they're in there for fear of letting an infectee in.
The sequel confirms that some did escape the country, while numerous dead bodies are found inside of building or just any other structures, like metro tunnels.
And many simply were killed trying to hole up in their houses and apartments. Most of the locations visited were outdoors or public areas people would avoid once an epidemic was apparent (like a huge grocery store), and when they went into other buildings (like the church, Jim's house, or the gas station) they found corpses and/or Infected.
All those dead bodies in the building near the gas trunk they refueled from, and just one infected child in the whole place. What, were all those people his loved ones and couldn't bring themselves to fight back, even as he ripped them apart?
In the infected child scene as mentioned above, one could hear the infected child scream "I hate you". Could this mean the infected could be atleast semi-sentient and/or intelligent and are just consumed by rage to stop killing everything?
Just what were the researchers, or those funding their experiments, planning to do with their "cure" for anger, if it had worked as intended? An entire Stepford Smiler nation, perhaps? Happiness in Slavery?
28 Weeks Later's plot hinges on the existence of at least one asymptomatic infectee (well, that, and remarkably poor decision-making). There's no guarantee that there was only one, or that others might not have successfully escaped into the countryside or out of the country.