There have been no new cases of naturally occurring polio in North Ame

Question

There have been no new cases of naturally occurring polio in North America in recent years. Yet there are approximately 12 new cases of polio each year in North America, all caused by the commonly administered live oral polio vaccine (OPV). Substituting inactivated polio vaccine (IPV) for most childhood polio immunizations would cut the number of cases of vaccination-caused polio about in half. Clearly it is time to switch from OPV to IPV as the most commonly used polio vaccine for North American children.

Which one of the following, if true, most weakens the argument?

Which one of the following, if true, most weakens the argument?

(A) If IPV replaces OPV as the most commonly used polio vaccine, at least a few new cases of naturally occurring polio in North America will result each year.

(B) The vast majority of cases of polio caused by OPV have occurred in children with preexisting but unsuspected immunodeficiency disorders.

(C) A child’s risk of contracting polio from OPV has been estimated at 1 in 8.7 million, which is significantly less than the risk of being struck by lightning.

(D) Although IPV is preferred in some European nations, most countries with comprehensive child immunization programs use OPV.

(E) IPV, like most vaccines, carries a slight risk of inducing seizures in children with neurological diseases such as epilepsy.

Bunuel · Accepted Answer

EXPLANATION FROM Fox LSAT

The problem with this argument is that it only talks about how many cases of polio would be caused by the vaccine, while ignoring how many cases of polio the vaccines would prevent. It isn’t “clearly” time to switch to IPV if OPV is much better at preventing naturally occurring polio, even if OPV does cause a few extra cases of vaccine-induced polio.

A) This would be a stronger weakener if it said “many” instead of “at least a few.” But “at least a few” means “three or more,” which could include a hundred, a thousand, or a billion. So this could be the answer, if all the other answers suck.

B) The characteristics of the victims are not relevant. This neither strengthens nor weakens.

C) This is a sucker answer. Even rare risks should be minimized, if possible.

D) It doesn’t matter what other countries do.

E) This is the most commonly-chosen incorrect answer, but how do we know OPV doesn’t have the exact same risk of inducing seizures? This answer says “like most vaccines.” Isn’t OPV a vaccine?

Since none of the other answers is any good, and since A could be a great weakener if “at least a few” means more than just a handful, our answer is A.

Nidzo · Answer

(A) This weakens the argument. While IPVs may cut the number of cases of vaccination-caused polio in half, it would result in the number of natural infections to increase to a number which may well surpass the number vaccination-caused polio cases which would be prevented.  Correct

(B) The immunodeficiency disorders of some of the children has no relevance to the argument at hand.  Incorrect 
 
(C) Comparing the likelihood of contracting polio from OBV to that of being struck by lightning is irrelevant to the argument.  Incorrect

(D) This provides no information on which of the vaccines is more effective, which is what the argument is about.  Incorrect

(E) Does not provide information pertaining to the effectiveness of the vaccine, merely that there are risks, as is the case with most vaccines.  Incorrect

Answer A

REALMAREZ · Answer

A 
 Conclusion:  Clearly it is time to switch from OPV to IPV as the most commonly used polio vaccine for North American children.

The conclusion is comapring OPV and IPV.--> One tip is to look for an answer that deals with both OPV and IPV (A, D: D is out of scope, so A is the right answer choice)

You can also spend few more seconds on the answer choices and Nidzo explained every a.c. greatly.

(A) If IPV replaces OPV as the most commonly used polio vaccine, at least a few new cases of naturally occurring polio in North America will result each year.

(B) The vast majority of cases of polio caused by OPV have occurred in children with preexisting but unsuspected immunodeficiency disorders.

(C) A child’s risk of contracting polio from OPV has been estimated at 1 in 8.7 million, which is significantly less than the risk of being struck by lightning.

(D) Although IPV is preferred in some European nations, most countries with comprehensive child immunization programs use OPV.

(E) IPV, like most vaccines, carries a slight risk of inducing seizures in children with neurological diseases such as epilepsy.

Sumi1010 · Answer

Premise - No naturally occurring polio. The cases are due to OPV.
Conclusion - Switch from OPV to IPV would cut the number of cases.

Prethink -
For the problems like this one, in which - we have two causing factors and the argument favors/rejects one for another,
the common approaches to attack are:
1. Show that the two factors are connected or related.
2. Show the benefits of one over threats of another.

e.g. If IPV and OPV are so connected that switch is actually not a considerable approach, then the plan itself falls apart.

(A) If IPV replaces OPV as the most commonly used polio vaccine, at least a few new cases of naturally occurring polio in North America will result each year.
If true, switching from OPV to IPV will not help in reducing the number of cases.
Attacks the argument.
(B) The vast majority of cases of polio caused by OPV have occurred in children with preexisting but unsuspected immunodeficiency disorders.
As soon as I read "polio caused by OPV" , I really don't care about the additional information.
As the choice still believes that "polio caused by OPV" and hence can't attack the argument.
(C) A child’s risk of contracting polio from OPV has been estimated at 1 in 8.7 million, which is significantly less than the risk of being struck by lightning.
Who is talking about lightning?

(D) Although IPV is preferred in some European nations, most countries with comprehensive child immunization programs use OPV.
What most countries do may not be always the efficient thing.
(E) IPV, like most vaccines, carries a slight risk of inducing seizures in children with neurological diseases such as epilepsy.
We must gauge the harms and benefits for the plan.
For a weakening problem -
If a change (for the planned benefit X) brings a "significant" harm Y - the change can't be a good idea.
This choice is not a "good" candidate for weakening the argument only because the choice says " a slight risk".
If I remove the adjective "slight", this could be a potential choice for weakening the argument for the threat it talks about.

A wins over E

IMO A.

A wins over E IMO A.

sivatx2 · Answer

due to vaccines **naturally** occurring polio = 0
vaccine 2 types:
 1. OPV - # of vaccine caused polio is x.
 2. IPV - # of vaccine caused polio is x/2.
OPV is currently used, & causes 12 cases/year of vaccine caused polio. If IPV used it will become 6 cases/year.
=> IPV should be used.

We need to prove that IPV should not be used, with a reason.

(A) If IPV replaces OPV as the most commonly used polio vaccine, at least a few new cases of naturally occurring polio in North America will result each year. 
 This option opens up a can of worm, that old problem (naturally occuring polio) going to occur if IPV used. This is definitely weakening the argument. Keep

(B) The vast majority of cases of polio caused by OPV have occurred in children with preexisting but unsuspected immunodeficiency disorders. 
 This does not weaken by proving why IPV should not be used. Eliminate

(C) A child’s risk of contracting polio from OPV has been estimated at 1 in 8.7 million, which is significantly less than the risk of being struck by lightning. 
 This gives statistical information on OPV. What about IPV? How can I prove IPV should not be used? This option is useless. Eliminate

(D) Although IPV is preferred in some European nations, most countries with comprehensive child immunization programs use OPV. 
 This option, with "Preference", does not provide any reasoning why IPV should not be used. Eliminate

(E) IPV, like most vaccines, carries a slight risk of inducing seizures in children with neurological diseases such as epilepsy.
 This option misses comparing the risk of IPV with that of OPV. So we don't know which is better, and we are looking for option to say IPV should not be used. Eliminate.

Hence, A is the best answer choice.

Crytiocanalyst · Answer

(A) If IPV replaces OPV as the most commonly used polio vaccine, at least a few new cases of naturally occurring polio in North America will result each year.
OPV compled eradicaed natural infections and only created some fewer non-anticipated cases if IPV is not able tocurtail the former it significantly weakens the argument therefore let us hang on to it

(B) The vast majority of cases of polio caused by OPV have occurred in children with preexisting but unsuspected immunodeficiency disorders.
This lends strength to the fact Opv wasn't the prime cause however this doesn't eleminate the fact that IPV has a better results which we cannot definitively decide therefore out

(C) A child’s risk of contracting polio from OPV has been estimated at 1 in 8.7 million, which is significantly less than the risk of being struck by lightning.
IPV rating might better off or worse we cannot quantitatively define therefore out

(D) Although IPV is preferred in some European nations, most countries with comprehensive child immunization programs use OPV.
What others prefer is absolutely inconsequential therefore out

(E) IPV, like most vaccines, carries a slight risk of inducing seizures in children with neurological diseases such as epilepsy.
we don't have the data suggesting the rate OPV therefore out

THerefore IMO A

KushagraKirtiman · Answer

Is it not outside information that IPV may cause naturally induced polio??

Abhishek009 · Answer

Here is my workout -

Recent Yrs : No new (Nat) polio cases in NA.
12 New cases/Yr in NA (OPV) = COUNTER :  IPV ---> OPV/2

SWITCH : OPV--->IPV.

The issue is about Naturally occurring Polio Vs manmade Polio...

Switching from OPV to IPV will result in half but option (A) is the only option which states that it will result in new Naturally occurring cases (Which presently is nil in recent years), which is not acceptable and it goes against the conclusion " Clearly it is time to switch from OPV to IPV as the most commonly used polio vaccine for North American children."

Check all the other options, none touches this point.

Ankanleo · Answer

Isn't the conclusion exclusively talking about vaccination-caused polio? If that's the case, then I don't think A is the best answer to this question. If the conclusion had instead said "total number of polio cases", then A would have been the weakener. Otherwise B gives us an alternate scenario as to why the vaccination based polio occurred and using IPV instead of OPV might not solve the problem by half.

guddo · Answer

I’d say the key point is that the conclusion is  not  “IPV will reduce vaccination-caused polio.” That is already given as a premise. The conclusion is the broader recommendation that  North America should switch from OPV to IPV .

So (A) directly weakens that recommendation by showing an important harmful consequence of switching: naturally occurring polio would return.

(B) does not weaken the argument because it does not challenge the stated fact that switching to IPV would cut vaccination-caused cases about in half. It only tells us which children are especially vulnerable to OPV.

egmat · Answer

Hi Ankanleo,

You're reading the support carefully, and you're right that the  premise  about "cut the number of cases of vaccination-caused polio about in half" is scoped to vaccine-caused cases. But look at what the  conclusion  actually recommends:  "it is time to switch from OPV to IPV as the most commonly used polio vaccine for North American children."

That's a  recommendation / plan , not a claim about a single statistic. And whenever an argument concludes "we should do X," the real goal behind it is the children's overall polio situation - the fewest kids getting polio, period. So the conclusion is  not  fenced off to only vaccine-caused polio; that number is just the evidence offered for the plan.

Why A weakens

To evaluate a plan, you weigh its  net effect  - the benefit it claims  minus  any new harm it introduces. (A) says the switch would cause "at least a few new cases of naturally occurring polio ... each year." Right now that number is  zero . So the plan buys us ~ 6  fewer vaccine-caused cases but creates a brand-new source of polio that didn't exist before. That directly undercuts the "clearly it's time to switch" recommendation. This isn't outside knowledge - the choice hands you the fact and asks you to accept it as true.

Why B doesn't

Here's the key: the halving is stated as a  given premise  - "would cut the number of cases ... about in half." You must accept that as true. (B) only tells you  who  the OPV victims tend to be (kids with immunodeficiency disorders). Even if true, that does nothing to stop IPV from still halving the count. It's  true-but-irrelevant  - it neither blocks the benefit nor adds a cost.

Quick gut-check to lock it in:  suppose the conclusion instead said,  "switch delivery vans to a cheaper model - it cuts fuel cost in half."  Which weakens?
- "The cheaper vans break down constantly, needing costly repairs." (a new cost - weakens)
- "Most fuel is burned on highway routes." (just describes the situation - does nothing)

A is the first kind; B is the second.

Answer: A

There have been no new cases of naturally occurring polio in North Ame

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There have been no new cases of naturally occurring polio in North Ame

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615 to 715 in 15 Days (Ria's Strategies)

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Perfect 805 Score Debrief by Julia

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