If you look at almost any movie about the zombie apocalypse you should have noted that there are two aspects of the Zompoc depicted which is the same across the board. Firstly the majority of the human species are turned into zombies.
The actual number of humans at the end of the primary spread of the infection is a very limited number. The fiction commonly shows this being the result of luck in escaping or being in a position where humans were overlooked by the infected. There is also the safety found in being initially located a decent distance from the initial infection.
The second common aspect is the speed of transmission of the virus and conversion of humans into infected. In this the speed of conversion can go from 12 seconds in the example of the movie World War Z to a number of hours as seen in the Walking Dead.
Any response to a zombie outbreak is commonly found to be insufficient to control the spread. We submit that this is primarily due to two factors. The first is the short incubation period and the second is the mobility and intentional infection of others by the zombie.
To examine this we start with looking at Ebola as an example and some terminology. The period of time between people being infected with a disease and demonstrating symptoms of the disease is called the incubation period. As such where we have used the term, “conversion” above the actual term should be incubation. However terminology may be confusing in the zombie instance.
The reason we say confusing is that it is not a strict rule all diseases are infectious to other persons at the time symptoms appear. In the case of zombies, the symptoms are clearly the transition from a human to a zombie. Much of the fiction agrees that this is characterised by a change in skin colour to a whiter or grey blue colour and changes to the colouration of the eyes. Next the converted are trying to eat you.
At this stage we are looking at essentially the symptoms of the disease and the capability of the infected to transmit the disease.
Ebola has an incubation period during which a person is infected but not shedding the virus (potentially infecting other persons) of 2 to 21 days. At the end of the incubation period the person begins to display the initial symptoms of the disease. These are fever, fatigue, muscle pain headache and sore throat. As the reader will appreciate the symptoms could relate to a number of maladies. Therefore there can be a delay in diagnosis.
Transmission of Ebola is by way of direct contact with blood, bodily secretions, mucus membranes and items contaminated with these fluids such as bedding.
One thing we have not seen often in the fiction is the idea that blood from an infected person prior to conversion to a zombie is infectious. The fiction often shows persons who have been bitten by a zombie being treated by uninfected without proper precaution to prevent fluid contact. This suggests that the transmission is primarily by way of bite.
However this is only conjecture and we will operate in this article for simplicity the assumption that the blood of a zombie is potentially infectious but not until conversion.
Ebola is a highly infectious disease and we use it a comparative to imagine the transmission of the zombie virus. As Ebola in 2014 was a hot topic news item with the largest recorded outbreak it makes for a useful comparative to imagine.
Of course one aspect of the Ebola outbreaks was the ability to quarantine those infected with Ebola to prevent the spread of the disease. Where barrier treatment was not implemented health care providers became infected and had to be quarantined.
Cultural practices of physical contact with the deceased also led to transmission of the disease until this was incorporated into the quarantine system.
So considering Ebola we have a highly infectious disease that requires strict and careful barrier protection for health care workers and quarantine. During the initial phases of an Ebola outbreak a large number of healthcare providers become infected as the disease is not diagnosed until after the more extreme symptoms such as the haemorrhagic fever sets in. Thus health care providers are exposed until diagnosis and proper protocols put in place.
Now let’s compare to the zombie. The zombie is highly infectious if you are bitten. If bitten you will contract the disease and likely convert. The zombie unlike the Ebola patient is highly mobile and will attack healthcare workers and seek to leave a quarantine area. The Ebola patient is too sick to do either of those things.
As such when considering the spread of the zombie virus (or whatever the method is such as bacterial or prions) the fact the infected are mobile means they need to be contained by forceful physical means. Further they purposefully seeking to infect others either by instinct to spread the virus or merely due to the desire to bite people for food or fun.
We raise this issue to demonstrate that a zombie outbreak may not even be diagnosed until after the disease has started to spread rapidly. Further even when recognised, the standard quarantine procedures and protections are not going to be effective against those infected as zombies. Not effective due to the fact standard protocols don’t involve locking the infected up so they can’t get out and needing strong walls and doors to ensure this.
These factors we submit will have an influence of the reaction time of those seeking to treat the infected or control the outbreak.
We assume that protocols such as those used for Ebola which are quite strict would be used in a zombie scenario. As we can further surmise that standard protocols for management of such diseases as Ebola will fail as a method of containment.
If we therefore surmise there is a mobile infection in the fast running or walking / shambling zombie the next consideration is geography.
In some scenarios the luck related to being in a place where the concentration of the infected was low such as in rural areas was likely the primary factor in the occurrence of survivors. For example in Season 2 of the Walking Dead we find Hershel’s farm is a haven with survivors, primarily due to geographic features which made incursion into the farm by the infected rare. Well at least until a hoard was attracted by the Rick-Shane fracas and dropped the fences.
The ultimate luck is of course being overlooked. In 28 Days later and the Walking dead it is the overlooked hospital patient that has the luck of a leprechaun to be at a primary infection site and not be infected.
Unfortunately only a fraction of the population will have the benefits of location such as Herschel’s farm (keeping in mind most of his neighbours were infected) or the extraordinary luck of Rick Grimes in The Walking Dead.
Therefore we need to consider whether we even have a chance against such a spread of infection. To do this we need to examine the mathematical models that offer some predictive power of the spread of the zombies.
The main thing of interest in the spread of the zombie infection is the mathematics that tracks the infection rate is very different to the standard calculation of infection rates. The models are primarily concerned with infection rates, the calculation of how the disease goes from a single or small group of infected to a larger group.
Where an infected person only infects one other person the disease is considered endemic. In this responses to the disease can be fairly simple as you are dealing with a small pool if infectious persons. If you intercept the infectious and quarantine them or otherwise prevent them from contact with others the spread is managed.
Where the spread is not a one to one and the infected can infect more than one then the spread of the disease will be an epidemic and demonstrate exponential growth.
This can be demonstrated by the simple equation (y)x . If we say that y is the number of infected persons at a given time and the infection rate is two persons then y will change as follows, 1;2;4;16;256;65,536;4,294,967,296, and on.
This is a reproductive ratio of 2. The Epidemiological notation for this is R0.
For some well-known diseases the R0 is fairly well established. HIV is 2 to 5, Smallpox 3 to 5 and Measles 16 to 18. This is a number based on a totally susceptible population. The equations are of course modified where there is resistance to the infection such as immunisation rate or natural immunity.
This is of course an incredibly simplistic model in that it states that those infected are not removed from the infection pool being y. In reality people recover or die or otherwise are prevented from spreading infection thus being removed from the infection pool.
For example a new strain of influenza occurs in a population that has no defence in the form of immunity. Thus you have a fully susceptible population. Initially there is an exponential growth in cases however as the pool of susceptible decreases the rate of growth in infected numbers decreases. This decline can mean that the disease dies out due to not traveling to new hosts before the entire population is infected.
As indicated above, Zombies are possibly a different prospect entirely.
Munz et al 2009 in their paper, “When Zombies Attack!: Mathematical Modelling of an Outbreak of Zombie Infection” discuss their equations for modelling the spread of a zombie outbreak.
Of particular note is the differences the zombie outbreak presents compared to the standard model. In the standard model the infected go into one of two primary categories, dead or recovered. In this these persons are removed from the pool of people capable of infecting others. Alas with the zombies there is no recovery or death (except when shot in the head of course). Those who are infected will continue to be a source of infection until they are destroyed.
A number of conclusions are reached in regards to the potential survival of the human species and it is not a positive outcome. At page 146 Munz et al state:
“…These results assumed that the time scale of the outbreak was short, so that the natural birth and deathrates could be ignored. If the time scale of the outbreak increases, then the result is the doomsday scenario: an outbreak of zombies will result in the collapse of civilisation with every human infected or dead.
In the paper a number of tactics to prevent the apocalyptic scenario are considered in relation to prevention of the spread of the disease.
Quarantine is considered but it suggests only aggressive quarantine will be effective. In this the primary method to control the spread of infection is offensive in nature by hitting them hard and often. Essentially killing off the source of infection one headshot at a time.
The Munz paper has been criticised in regards to some of the assumptions made in the paper. Your writer has noted that the paper in its introduction talks about cemeteries being a source of infected. We do not believe that an already dead body can subsequently contract the infection and reanimate.
However looking at the calculations this assumption is unlikely to have had any impact on the actual model proposed or the outcome of the paper.
A presentation by Cait Witkowski and Brian Blais in 2013, “Zombie Apocalypse: An Epidemic Model challenge the Munz paper critiqued the assumptions in the Munz paper and further used some date to test the calculations.
The first notable criticism by Witkowski and Blais is that the Munz paper does not fully integrate the death rates and latent periods of infection. By using data from the popular movies they adjusted a number of the parameters and crunched some numbers.
The conclusion they reached was the zombie infection was likely to be disastrous but not inevitable.
In this we are looking at a presentation and not a published paper. However if we assume the presentation is of a type peer reviewed and substantial in its findings then we still have a “likely” outcome of everyone being basically a zombie or dead.
Thus the modelling suggests that infection during the Zompoc is likely. Yep you are likely to be infected.
Now the perceptive reader will have noted the above studies do not consider all the potential factors. The models being used were not meant to do that,. They merely look at the model of the disease from the perspective of disease spread within a population.
If we factor in some geographical factors and geographically located infection sources then we have a clearer picture of the spread of the infection and the possibility to avoid infection.
Two papers examine this aspect of the potential for survival. The most recent and notable is the 2015 Alexander Et al paper, “You Can Run, You Can Hide: The Epidemiology and Statistical Mechanics of Zombies.” Possibly most notable given it studies the continental United States and there was an interactive map of the progression of the outbreak.
A previous paper by Thomas et al in 2014, “How Long can we survive” in Mathematical Modelling of Zombies, University of Ottawa (note there is a connection between this paper and the previous Munz et al paper being the same research centre and including likely involvement by authors of the original study
What these studies found was that the fact the zombie is mobile has an enormous impact on the spread of infection. Thus if for example there is an outbreak of an Ebola like disease in a city the population may die out in place and the disease will also die out. Only if people move from the city to another city can there be transmission.
In the Ebola like scenario hiding in a place far away from other people could create a barrier of distance from our hypothetical disease. Zombie however can move on their own and have the potential to spread to all corners.
In this the Wolley, Baker et al paper considers that zombies will randomly diffuse. Thus zombies will spread everywhere as they will have little or no real intent on direction. As they spread the concentration of zombies within an area will decrease.
They conclude that you can run but eventually the surviving humans will have contact with the zombies. Distance and difficult terrain can extend the time before interaction however it’s going to happen.
They further conclude that in order to survive the potential survivor must do the following;
The Alexander et al paper gives us a time frame. Now of course these papers are looking at the structure of the mathematical models using a much more fun manner of describing them, the zombie. However using their calculations from initial outbreak to most of the population of the U.S. turning into zombies is by the first week of the outbreak.
After four weeks most of the country will have fallen as zombies diffuse almost all parts. However there will be areas that take much longer to get zombies. Remote areas of Nevada and Montana it is calculated will be zombie free at four months.
Now one of the issues these two papers have is the transmission of persons during the incubation periods ahead of the base spread of the disease.
To demonstrate we will use an example of an incubation period of 12 hours from infection to conversion. The person infected does not show any outward symptoms of the disease until they collapse and apparently die at the 12 hour mark. Once they collapse the time until they rise is only minutes.
In that time a person can travel or be transported great distances such as by aircraft, car or even walking. They can out run the diffusion of the zombie’s thus spreading infection more quickly.
In this instance a person might be infected and travel to an area in remote Montana to escape the zombies only to become the source of infection in the region. Given the speed people can travel remote areas could see zombies by way of transport of the infected during the incubation period arriving in remote areas on day one.
Therefore the probability you will survive the initial outbreak is low as the spread is possibly going to be faster than people can respond to. In order to escape you might need to run within the first few hours of an outbreak.
Considering that reports of an outbreak can be delayed due to a failure to diagnose you may not know of the outbreak in time. Think about the problem with reporting an outbreak where those sent to investigate become zombies and don’t do their job of reporting back except when they return in zombie form to eat their boss.
The ability of government bodies to respond to an outbreak is limited. Not because the government bodies are ineffective but due to the nature of the threat.
The response body must act in the following manner;
Even a bombing run on the invader will involve knowing where the invader is. Once known the planes are tasked to attack. There may well be pilots and planes on standby but they need to be briefed, the places warmed up, weapons loaded and then flight time to where the invader is.
Therefore given the speed of spread of the zombies it is unlikely any response from the military or other services capable of setting up an aggressive quarantine could react fast enough. Heck it could take hours before it is established they are zombies and are a mobile source of infection.
Therefore the probability of surviving the first week for the average person in unlikely. The delay in obtaining information makes most bug out plans get activated too late. Bugging in might be just as bad as the concentration of zombies and the fact most structures are not defensible means you go down.
Sorry but the news is poor for just about everyone who isn’t located in a region geographically placed to not be infected in the early stages.
Only those who are located in geographically remote places or can outrun the spread of the zombies will have time to prepare. Even then if the place of safety is not sustainable then you will merely die of hunger, other diseases or thirst long before the zombies break down the barricades.
Alexander et al, (2015), You can run, you can hide: The epidemiology and statistical mechanics of Zombies, Cornell University, arXic.1503.01104
Wooley, Baker, Gaffney, Maini, (2014), How long can we survive
Munz Et al, 2009, When Zombies Attack!: Mathematical modelling of an Outbreak of Zombie Infection. Infectious disease modelling progress, @pp 133-150.
The actual number of humans at the end of the primary spread of the infection is a very limited number. The fiction commonly shows this being the result of luck in escaping or being in a position where humans were overlooked by the infected. There is also the safety found in being initially located a decent distance from the initial infection.
The second common aspect is the speed of transmission of the virus and conversion of humans into infected. In this the speed of conversion can go from 12 seconds in the example of the movie World War Z to a number of hours as seen in the Walking Dead.
Any response to a zombie outbreak is commonly found to be insufficient to control the spread. We submit that this is primarily due to two factors. The first is the short incubation period and the second is the mobility and intentional infection of others by the zombie.
To examine this we start with looking at Ebola as an example and some terminology. The period of time between people being infected with a disease and demonstrating symptoms of the disease is called the incubation period. As such where we have used the term, “conversion” above the actual term should be incubation. However terminology may be confusing in the zombie instance.
The reason we say confusing is that it is not a strict rule all diseases are infectious to other persons at the time symptoms appear. In the case of zombies, the symptoms are clearly the transition from a human to a zombie. Much of the fiction agrees that this is characterised by a change in skin colour to a whiter or grey blue colour and changes to the colouration of the eyes. Next the converted are trying to eat you.
At this stage we are looking at essentially the symptoms of the disease and the capability of the infected to transmit the disease.
Ebola has an incubation period during which a person is infected but not shedding the virus (potentially infecting other persons) of 2 to 21 days. At the end of the incubation period the person begins to display the initial symptoms of the disease. These are fever, fatigue, muscle pain headache and sore throat. As the reader will appreciate the symptoms could relate to a number of maladies. Therefore there can be a delay in diagnosis.
Transmission of Ebola is by way of direct contact with blood, bodily secretions, mucus membranes and items contaminated with these fluids such as bedding.
One thing we have not seen often in the fiction is the idea that blood from an infected person prior to conversion to a zombie is infectious. The fiction often shows persons who have been bitten by a zombie being treated by uninfected without proper precaution to prevent fluid contact. This suggests that the transmission is primarily by way of bite.
However this is only conjecture and we will operate in this article for simplicity the assumption that the blood of a zombie is potentially infectious but not until conversion.
Ebola is a highly infectious disease and we use it a comparative to imagine the transmission of the zombie virus. As Ebola in 2014 was a hot topic news item with the largest recorded outbreak it makes for a useful comparative to imagine.
Of course one aspect of the Ebola outbreaks was the ability to quarantine those infected with Ebola to prevent the spread of the disease. Where barrier treatment was not implemented health care providers became infected and had to be quarantined.
Cultural practices of physical contact with the deceased also led to transmission of the disease until this was incorporated into the quarantine system.
So considering Ebola we have a highly infectious disease that requires strict and careful barrier protection for health care workers and quarantine. During the initial phases of an Ebola outbreak a large number of healthcare providers become infected as the disease is not diagnosed until after the more extreme symptoms such as the haemorrhagic fever sets in. Thus health care providers are exposed until diagnosis and proper protocols put in place.
Now let’s compare to the zombie. The zombie is highly infectious if you are bitten. If bitten you will contract the disease and likely convert. The zombie unlike the Ebola patient is highly mobile and will attack healthcare workers and seek to leave a quarantine area. The Ebola patient is too sick to do either of those things.
As such when considering the spread of the zombie virus (or whatever the method is such as bacterial or prions) the fact the infected are mobile means they need to be contained by forceful physical means. Further they purposefully seeking to infect others either by instinct to spread the virus or merely due to the desire to bite people for food or fun.
We raise this issue to demonstrate that a zombie outbreak may not even be diagnosed until after the disease has started to spread rapidly. Further even when recognised, the standard quarantine procedures and protections are not going to be effective against those infected as zombies. Not effective due to the fact standard protocols don’t involve locking the infected up so they can’t get out and needing strong walls and doors to ensure this.
These factors we submit will have an influence of the reaction time of those seeking to treat the infected or control the outbreak.
We assume that protocols such as those used for Ebola which are quite strict would be used in a zombie scenario. As we can further surmise that standard protocols for management of such diseases as Ebola will fail as a method of containment.
If we therefore surmise there is a mobile infection in the fast running or walking / shambling zombie the next consideration is geography.
In some scenarios the luck related to being in a place where the concentration of the infected was low such as in rural areas was likely the primary factor in the occurrence of survivors. For example in Season 2 of the Walking Dead we find Hershel’s farm is a haven with survivors, primarily due to geographic features which made incursion into the farm by the infected rare. Well at least until a hoard was attracted by the Rick-Shane fracas and dropped the fences.
The ultimate luck is of course being overlooked. In 28 Days later and the Walking dead it is the overlooked hospital patient that has the luck of a leprechaun to be at a primary infection site and not be infected.
Unfortunately only a fraction of the population will have the benefits of location such as Herschel’s farm (keeping in mind most of his neighbours were infected) or the extraordinary luck of Rick Grimes in The Walking Dead.
Therefore we need to consider whether we even have a chance against such a spread of infection. To do this we need to examine the mathematical models that offer some predictive power of the spread of the zombies.
The main thing of interest in the spread of the zombie infection is the mathematics that tracks the infection rate is very different to the standard calculation of infection rates. The models are primarily concerned with infection rates, the calculation of how the disease goes from a single or small group of infected to a larger group.
Where an infected person only infects one other person the disease is considered endemic. In this responses to the disease can be fairly simple as you are dealing with a small pool if infectious persons. If you intercept the infectious and quarantine them or otherwise prevent them from contact with others the spread is managed.
Where the spread is not a one to one and the infected can infect more than one then the spread of the disease will be an epidemic and demonstrate exponential growth.
This can be demonstrated by the simple equation (y)x . If we say that y is the number of infected persons at a given time and the infection rate is two persons then y will change as follows, 1;2;4;16;256;65,536;4,294,967,296, and on.
This is a reproductive ratio of 2. The Epidemiological notation for this is R0.
For some well-known diseases the R0 is fairly well established. HIV is 2 to 5, Smallpox 3 to 5 and Measles 16 to 18. This is a number based on a totally susceptible population. The equations are of course modified where there is resistance to the infection such as immunisation rate or natural immunity.
This is of course an incredibly simplistic model in that it states that those infected are not removed from the infection pool being y. In reality people recover or die or otherwise are prevented from spreading infection thus being removed from the infection pool.
For example a new strain of influenza occurs in a population that has no defence in the form of immunity. Thus you have a fully susceptible population. Initially there is an exponential growth in cases however as the pool of susceptible decreases the rate of growth in infected numbers decreases. This decline can mean that the disease dies out due to not traveling to new hosts before the entire population is infected.
As indicated above, Zombies are possibly a different prospect entirely.
Munz et al 2009 in their paper, “When Zombies Attack!: Mathematical Modelling of an Outbreak of Zombie Infection” discuss their equations for modelling the spread of a zombie outbreak.
Of particular note is the differences the zombie outbreak presents compared to the standard model. In the standard model the infected go into one of two primary categories, dead or recovered. In this these persons are removed from the pool of people capable of infecting others. Alas with the zombies there is no recovery or death (except when shot in the head of course). Those who are infected will continue to be a source of infection until they are destroyed.
A number of conclusions are reached in regards to the potential survival of the human species and it is not a positive outcome. At page 146 Munz et al state:
“…These results assumed that the time scale of the outbreak was short, so that the natural birth and deathrates could be ignored. If the time scale of the outbreak increases, then the result is the doomsday scenario: an outbreak of zombies will result in the collapse of civilisation with every human infected or dead.
In the paper a number of tactics to prevent the apocalyptic scenario are considered in relation to prevention of the spread of the disease.
Quarantine is considered but it suggests only aggressive quarantine will be effective. In this the primary method to control the spread of infection is offensive in nature by hitting them hard and often. Essentially killing off the source of infection one headshot at a time.
The Munz paper has been criticised in regards to some of the assumptions made in the paper. Your writer has noted that the paper in its introduction talks about cemeteries being a source of infected. We do not believe that an already dead body can subsequently contract the infection and reanimate.
However looking at the calculations this assumption is unlikely to have had any impact on the actual model proposed or the outcome of the paper.
A presentation by Cait Witkowski and Brian Blais in 2013, “Zombie Apocalypse: An Epidemic Model challenge the Munz paper critiqued the assumptions in the Munz paper and further used some date to test the calculations.
The first notable criticism by Witkowski and Blais is that the Munz paper does not fully integrate the death rates and latent periods of infection. By using data from the popular movies they adjusted a number of the parameters and crunched some numbers.
The conclusion they reached was the zombie infection was likely to be disastrous but not inevitable.
In this we are looking at a presentation and not a published paper. However if we assume the presentation is of a type peer reviewed and substantial in its findings then we still have a “likely” outcome of everyone being basically a zombie or dead.
Thus the modelling suggests that infection during the Zompoc is likely. Yep you are likely to be infected.
Now the perceptive reader will have noted the above studies do not consider all the potential factors. The models being used were not meant to do that,. They merely look at the model of the disease from the perspective of disease spread within a population.
If we factor in some geographical factors and geographically located infection sources then we have a clearer picture of the spread of the infection and the possibility to avoid infection.
Two papers examine this aspect of the potential for survival. The most recent and notable is the 2015 Alexander Et al paper, “You Can Run, You Can Hide: The Epidemiology and Statistical Mechanics of Zombies.” Possibly most notable given it studies the continental United States and there was an interactive map of the progression of the outbreak.
A previous paper by Thomas et al in 2014, “How Long can we survive” in Mathematical Modelling of Zombies, University of Ottawa (note there is a connection between this paper and the previous Munz et al paper being the same research centre and including likely involvement by authors of the original study
What these studies found was that the fact the zombie is mobile has an enormous impact on the spread of infection. Thus if for example there is an outbreak of an Ebola like disease in a city the population may die out in place and the disease will also die out. Only if people move from the city to another city can there be transmission.
In the Ebola like scenario hiding in a place far away from other people could create a barrier of distance from our hypothetical disease. Zombie however can move on their own and have the potential to spread to all corners.
In this the Wolley, Baker et al paper considers that zombies will randomly diffuse. Thus zombies will spread everywhere as they will have little or no real intent on direction. As they spread the concentration of zombies within an area will decrease.
They conclude that you can run but eventually the surviving humans will have contact with the zombies. Distance and difficult terrain can extend the time before interaction however it’s going to happen.
They further conclude that in order to survive the potential survivor must do the following;
- Escape the initial outbreak without becoming infected
- Find a defensible location that can sustain a population of survivors
- Fortify the location against zombie incursion
- Be more deadly than the zombies and eradicate any zombies which wander into the fortifications locale
The Alexander et al paper gives us a time frame. Now of course these papers are looking at the structure of the mathematical models using a much more fun manner of describing them, the zombie. However using their calculations from initial outbreak to most of the population of the U.S. turning into zombies is by the first week of the outbreak.
After four weeks most of the country will have fallen as zombies diffuse almost all parts. However there will be areas that take much longer to get zombies. Remote areas of Nevada and Montana it is calculated will be zombie free at four months.
Now one of the issues these two papers have is the transmission of persons during the incubation periods ahead of the base spread of the disease.
To demonstrate we will use an example of an incubation period of 12 hours from infection to conversion. The person infected does not show any outward symptoms of the disease until they collapse and apparently die at the 12 hour mark. Once they collapse the time until they rise is only minutes.
In that time a person can travel or be transported great distances such as by aircraft, car or even walking. They can out run the diffusion of the zombie’s thus spreading infection more quickly.
In this instance a person might be infected and travel to an area in remote Montana to escape the zombies only to become the source of infection in the region. Given the speed people can travel remote areas could see zombies by way of transport of the infected during the incubation period arriving in remote areas on day one.
Therefore the probability you will survive the initial outbreak is low as the spread is possibly going to be faster than people can respond to. In order to escape you might need to run within the first few hours of an outbreak.
Considering that reports of an outbreak can be delayed due to a failure to diagnose you may not know of the outbreak in time. Think about the problem with reporting an outbreak where those sent to investigate become zombies and don’t do their job of reporting back except when they return in zombie form to eat their boss.
The ability of government bodies to respond to an outbreak is limited. Not because the government bodies are ineffective but due to the nature of the threat.
The response body must act in the following manner;
- Become aware of the outbreak
- Have sufficient information on the nature of the outbreak to act appropriately
- Develop an appropriate plan of action
- Gather and or task resources to attend to the plan of action
- Time in transit of the resources to the site of the infection.
Even a bombing run on the invader will involve knowing where the invader is. Once known the planes are tasked to attack. There may well be pilots and planes on standby but they need to be briefed, the places warmed up, weapons loaded and then flight time to where the invader is.
Therefore given the speed of spread of the zombies it is unlikely any response from the military or other services capable of setting up an aggressive quarantine could react fast enough. Heck it could take hours before it is established they are zombies and are a mobile source of infection.
Therefore the probability of surviving the first week for the average person in unlikely. The delay in obtaining information makes most bug out plans get activated too late. Bugging in might be just as bad as the concentration of zombies and the fact most structures are not defensible means you go down.
Sorry but the news is poor for just about everyone who isn’t located in a region geographically placed to not be infected in the early stages.
Only those who are located in geographically remote places or can outrun the spread of the zombies will have time to prepare. Even then if the place of safety is not sustainable then you will merely die of hunger, other diseases or thirst long before the zombies break down the barricades.
Alexander et al, (2015), You can run, you can hide: The epidemiology and statistical mechanics of Zombies, Cornell University, arXic.1503.01104
Wooley, Baker, Gaffney, Maini, (2014), How long can we survive
Munz Et al, 2009, When Zombies Attack!: Mathematical modelling of an Outbreak of Zombie Infection. Infectious disease modelling progress, @pp 133-150.