Father gets chickenpox, but doesn't infect his two children. How is this possible?
My brother in law got chickenpox, yet somehow he didn't infect my two nephews, even though they are living together. According to wikipedia, varicella has an infection rate of 90%:
Varicella is highly communicable, with an infection rate of 90% in close contacts.
https://en.wikipedia.org/wiki/Chickenpox
He got varicella over a week ago and the children are completely healthy, even though they have not had the disease yet nor are they vaccinated against it.
How is this possible? Is the infection rate actually lower, than 90%? Is an outcome like this usual or plausible?
infection vaccination virus chickenpox
asked 5 hours ago
user1721135user1721135
21015
add a comment |
My brother in law got chickenpox, yet somehow he didn't infect my two nephews, even though they are living together. According to wikipedia, varicella has an infection rate of 90%:
Varicella is highly communicable, with an infection rate of 90% in close contacts.
https://en.wikipedia.org/wiki/Chickenpox
He got varicella over a week ago and the children are completely healthy, even though they have not had the disease yet nor are they vaccinated against it.
How is this possible? Is the infection rate actually lower, than 90%? Is an outcome like this usual or plausible?
infection vaccination virus chickenpox
asked 5 hours ago
user1721135user1721135
21015
1
Adults with primary VZV infection (chickenpox syndrome) are usually VERY sick, often with interstitial pneumonia, and often require hospitalization. Are you certain he didn't have secondary VZV infection (shingles syndrome)?
– De Novo
4 hours ago
add a comment |
My brother in law got chickenpox, yet somehow he didn't infect my two nephews, even though they are living together. According to wikipedia, varicella has an infection rate of 90%:
Varicella is highly communicable, with an infection rate of 90% in close contacts.
https://en.wikipedia.org/wiki/Chickenpox
He got varicella over a week ago and the children are completely healthy, even though they have not had the disease yet nor are they vaccinated against it.
How is this possible? Is the infection rate actually lower, than 90%? Is an outcome like this usual or plausible?
infection vaccination virus chickenpox
asked 5 hours ago
user1721135user1721135
21015
My brother in law got chickenpox, yet somehow he didn't infect my two nephews, even though they are living together. According to wikipedia, varicella has an infection rate of 90%:
Varicella is highly communicable, with an infection rate of 90% in close contacts.
https://en.wikipedia.org/wiki/Chickenpox
He got varicella over a week ago and the children are completely healthy, even though they have not had the disease yet nor are they vaccinated against it.
How is this possible? Is the infection rate actually lower, than 90%? Is an outcome like this usual or plausible?
infection vaccination virus chickenpox
infection vaccination virus chickenpox
asked 5 hours ago
user1721135user1721135
21015
asked 5 hours ago
user1721135user1721135
21015
asked 5 hours ago
user1721135user1721135
21015
asked 5 hours ago
user1721135user1721135
21015
asked 5 hours ago
user1721135user1721135
21015
21015
1
Adults with primary VZV infection (chickenpox syndrome) are usually VERY sick, often with interstitial pneumonia, and often require hospitalization. Are you certain he didn't have secondary VZV infection (shingles syndrome)?
– De Novo
4 hours ago
add a comment |
1
Adults with primary VZV infection (chickenpox syndrome) are usually VERY sick, often with interstitial pneumonia, and often require hospitalization. Are you certain he didn't have secondary VZV infection (shingles syndrome)?
– De Novo
4 hours ago
1
1
Adults with primary VZV infection (chickenpox syndrome) are usually VERY sick, often with interstitial pneumonia, and often require hospitalization. Are you certain he didn't have secondary VZV infection (shingles syndrome)?
– De Novo
4 hours ago
Adults with primary VZV infection (chickenpox syndrome) are usually VERY sick, often with interstitial pneumonia, and often require hospitalization. Are you certain he didn't have secondary VZV infection (shingles syndrome)?
– De Novo
4 hours ago
add a comment |
2 Answers
2
active
oldest
votes
If there was close contact, if the 90% rate is accurate, and if occurrence is independent in related individuals, then you would expect 0.10 * 0.10 = 1% of contacts with 2 potentially vulnerable people to result in neither person infected.
1% sounds rare, but rare events happen all the time, and 1% isn't even particularly rare. If you know 100 families, you'd expect this outcome to happen on average in 1 of them.
That's not very unusual and is clearly plausible just from the information you have at hand. As @DeNovo mentioned in a comment, it is also likely that the spread is not independent, because the children share several characteristics: they are related, so they share:
- any genetic component to vulnerability
- any characteristics of the father's illness such as the level of virus replicating in the father's lungs
- perhaps the level of actual contact with the father and how well he may be effectively quarantined from the others
Those factors could make the joint probability trend towards the 10% rate for a single individual.
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
1
Re: this probability answer (which makes a good and important point, +1), I'd point out that infection of child A and of child B are not independent events. So, given an infected father, while the likelihood of child A not being infected is 10% and the likelihood of child B not being infected is 10%, the likelihood of neither of them being infected is closer to 10% than 1%. As far as the mechanism is concerned, the virus may not be replicating in the fathers lungs (or replicating at a lower dose), meaning the father is less likely to transmit.
– De Novo
4 hours ago
2
@DeNovo Yeah, I meant my answer to be sort of a lower bound on the probability, with 1% still being a fairly common occurrence. I added a discussion of some of the likely causes for non-independence.
– Bryan Krause
4 hours ago
add a comment |
To add to @BrynKrause's answer re: rare events happen all the time, the children are not out of the woods yet. The mean incubation time for a primary VZV infection (the clinical syndrome known as chicken pox) is 14 days, but often lasts up to 21 days (see Murray Medical Microbiology, Ch. 53). The father is infectious while shedding virus, usually via the lungs. This correlates with the period of time a patient is febrile. I wouldn't say the father didn't infect his children until he has been afebrile for 21 days.
answered 4 hours ago
De NovoDe Novo
1,85415
add a comment |
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2 Answers
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If there was close contact, if the 90% rate is accurate, and if occurrence is independent in related individuals, then you would expect 0.10 * 0.10 = 1% of contacts with 2 potentially vulnerable people to result in neither person infected.
1% sounds rare, but rare events happen all the time, and 1% isn't even particularly rare. If you know 100 families, you'd expect this outcome to happen on average in 1 of them.
That's not very unusual and is clearly plausible just from the information you have at hand. As @DeNovo mentioned in a comment, it is also likely that the spread is not independent, because the children share several characteristics: they are related, so they share:
- any genetic component to vulnerability
- any characteristics of the father's illness such as the level of virus replicating in the father's lungs
- perhaps the level of actual contact with the father and how well he may be effectively quarantined from the others
Those factors could make the joint probability trend towards the 10% rate for a single individual.
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
1
Re: this probability answer (which makes a good and important point, +1), I'd point out that infection of child A and of child B are not independent events. So, given an infected father, while the likelihood of child A not being infected is 10% and the likelihood of child B not being infected is 10%, the likelihood of neither of them being infected is closer to 10% than 1%. As far as the mechanism is concerned, the virus may not be replicating in the fathers lungs (or replicating at a lower dose), meaning the father is less likely to transmit.
– De Novo
4 hours ago
2
@DeNovo Yeah, I meant my answer to be sort of a lower bound on the probability, with 1% still being a fairly common occurrence. I added a discussion of some of the likely causes for non-independence.
– Bryan Krause
4 hours ago
add a comment |
If there was close contact, if the 90% rate is accurate, and if occurrence is independent in related individuals, then you would expect 0.10 * 0.10 = 1% of contacts with 2 potentially vulnerable people to result in neither person infected.
1% sounds rare, but rare events happen all the time, and 1% isn't even particularly rare. If you know 100 families, you'd expect this outcome to happen on average in 1 of them.
That's not very unusual and is clearly plausible just from the information you have at hand. As @DeNovo mentioned in a comment, it is also likely that the spread is not independent, because the children share several characteristics: they are related, so they share:
- any genetic component to vulnerability
- any characteristics of the father's illness such as the level of virus replicating in the father's lungs
- perhaps the level of actual contact with the father and how well he may be effectively quarantined from the others
Those factors could make the joint probability trend towards the 10% rate for a single individual.
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
1
Re: this probability answer (which makes a good and important point, +1), I'd point out that infection of child A and of child B are not independent events. So, given an infected father, while the likelihood of child A not being infected is 10% and the likelihood of child B not being infected is 10%, the likelihood of neither of them being infected is closer to 10% than 1%. As far as the mechanism is concerned, the virus may not be replicating in the fathers lungs (or replicating at a lower dose), meaning the father is less likely to transmit.
– De Novo
4 hours ago
2
@DeNovo Yeah, I meant my answer to be sort of a lower bound on the probability, with 1% still being a fairly common occurrence. I added a discussion of some of the likely causes for non-independence.
– Bryan Krause
4 hours ago
add a comment |
If there was close contact, if the 90% rate is accurate, and if occurrence is independent in related individuals, then you would expect 0.10 * 0.10 = 1% of contacts with 2 potentially vulnerable people to result in neither person infected.
1% sounds rare, but rare events happen all the time, and 1% isn't even particularly rare. If you know 100 families, you'd expect this outcome to happen on average in 1 of them.
That's not very unusual and is clearly plausible just from the information you have at hand. As @DeNovo mentioned in a comment, it is also likely that the spread is not independent, because the children share several characteristics: they are related, so they share:
- any genetic component to vulnerability
- any characteristics of the father's illness such as the level of virus replicating in the father's lungs
- perhaps the level of actual contact with the father and how well he may be effectively quarantined from the others
Those factors could make the joint probability trend towards the 10% rate for a single individual.
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
If there was close contact, if the 90% rate is accurate, and if occurrence is independent in related individuals, then you would expect 0.10 * 0.10 = 1% of contacts with 2 potentially vulnerable people to result in neither person infected.
1% sounds rare, but rare events happen all the time, and 1% isn't even particularly rare. If you know 100 families, you'd expect this outcome to happen on average in 1 of them.
That's not very unusual and is clearly plausible just from the information you have at hand. As @DeNovo mentioned in a comment, it is also likely that the spread is not independent, because the children share several characteristics: they are related, so they share:
- any genetic component to vulnerability
- any characteristics of the father's illness such as the level of virus replicating in the father's lungs
- perhaps the level of actual contact with the father and how well he may be effectively quarantined from the others
Those factors could make the joint probability trend towards the 10% rate for a single individual.
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
edited 4 hours ago
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
answered 5 hours ago
Bryan KrauseBryan Krause
1,488316
1,488316
1
Re: this probability answer (which makes a good and important point, +1), I'd point out that infection of child A and of child B are not independent events. So, given an infected father, while the likelihood of child A not being infected is 10% and the likelihood of child B not being infected is 10%, the likelihood of neither of them being infected is closer to 10% than 1%. As far as the mechanism is concerned, the virus may not be replicating in the fathers lungs (or replicating at a lower dose), meaning the father is less likely to transmit.
– De Novo
4 hours ago
2
@DeNovo Yeah, I meant my answer to be sort of a lower bound on the probability, with 1% still being a fairly common occurrence. I added a discussion of some of the likely causes for non-independence.
– Bryan Krause
4 hours ago
add a comment |
1
Re: this probability answer (which makes a good and important point, +1), I'd point out that infection of child A and of child B are not independent events. So, given an infected father, while the likelihood of child A not being infected is 10% and the likelihood of child B not being infected is 10%, the likelihood of neither of them being infected is closer to 10% than 1%. As far as the mechanism is concerned, the virus may not be replicating in the fathers lungs (or replicating at a lower dose), meaning the father is less likely to transmit.
– De Novo
4 hours ago
2
@DeNovo Yeah, I meant my answer to be sort of a lower bound on the probability, with 1% still being a fairly common occurrence. I added a discussion of some of the likely causes for non-independence.
– Bryan Krause
4 hours ago
1
1
Re: this probability answer (which makes a good and important point, +1), I'd point out that infection of child A and of child B are not independent events. So, given an infected father, while the likelihood of child A not being infected is 10% and the likelihood of child B not being infected is 10%, the likelihood of neither of them being infected is closer to 10% than 1%. As far as the mechanism is concerned, the virus may not be replicating in the fathers lungs (or replicating at a lower dose), meaning the father is less likely to transmit.
– De Novo
4 hours ago
Re: this probability answer (which makes a good and important point, +1), I'd point out that infection of child A and of child B are not independent events. So, given an infected father, while the likelihood of child A not being infected is 10% and the likelihood of child B not being infected is 10%, the likelihood of neither of them being infected is closer to 10% than 1%. As far as the mechanism is concerned, the virus may not be replicating in the fathers lungs (or replicating at a lower dose), meaning the father is less likely to transmit.
– De Novo
4 hours ago
2
2
@DeNovo Yeah, I meant my answer to be sort of a lower bound on the probability, with 1% still being a fairly common occurrence. I added a discussion of some of the likely causes for non-independence.
– Bryan Krause
4 hours ago
@DeNovo Yeah, I meant my answer to be sort of a lower bound on the probability, with 1% still being a fairly common occurrence. I added a discussion of some of the likely causes for non-independence.
– Bryan Krause
4 hours ago
add a comment |
To add to @BrynKrause's answer re: rare events happen all the time, the children are not out of the woods yet. The mean incubation time for a primary VZV infection (the clinical syndrome known as chicken pox) is 14 days, but often lasts up to 21 days (see Murray Medical Microbiology, Ch. 53). The father is infectious while shedding virus, usually via the lungs. This correlates with the period of time a patient is febrile. I wouldn't say the father didn't infect his children until he has been afebrile for 21 days.
answered 4 hours ago
De NovoDe Novo
1,85415
add a comment |
To add to @BrynKrause's answer re: rare events happen all the time, the children are not out of the woods yet. The mean incubation time for a primary VZV infection (the clinical syndrome known as chicken pox) is 14 days, but often lasts up to 21 days (see Murray Medical Microbiology, Ch. 53). The father is infectious while shedding virus, usually via the lungs. This correlates with the period of time a patient is febrile. I wouldn't say the father didn't infect his children until he has been afebrile for 21 days.
answered 4 hours ago
De NovoDe Novo
1,85415
add a comment |
To add to @BrynKrause's answer re: rare events happen all the time, the children are not out of the woods yet. The mean incubation time for a primary VZV infection (the clinical syndrome known as chicken pox) is 14 days, but often lasts up to 21 days (see Murray Medical Microbiology, Ch. 53). The father is infectious while shedding virus, usually via the lungs. This correlates with the period of time a patient is febrile. I wouldn't say the father didn't infect his children until he has been afebrile for 21 days.
answered 4 hours ago
De NovoDe Novo
1,85415
To add to @BrynKrause's answer re: rare events happen all the time, the children are not out of the woods yet. The mean incubation time for a primary VZV infection (the clinical syndrome known as chicken pox) is 14 days, but often lasts up to 21 days (see Murray Medical Microbiology, Ch. 53). The father is infectious while shedding virus, usually via the lungs. This correlates with the period of time a patient is febrile. I wouldn't say the father didn't infect his children until he has been afebrile for 21 days.
answered 4 hours ago
De NovoDe Novo
1,85415
answered 4 hours ago
De NovoDe Novo
1,85415
answered 4 hours ago
De NovoDe Novo
1,85415
answered 4 hours ago
De NovoDe Novo
1,85415
1,85415
add a comment |
add a comment |
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Adults with primary VZV infection (chickenpox syndrome) are usually VERY sick, often with interstitial pneumonia, and often require hospitalization. Are you certain he didn't have secondary VZV infection (shingles syndrome)?
– De Novo
4 hours ago