Saturday, August 11, 2018

New Zealand: Economic Evaluation Of Border Closure For A Generic Severe Pandemic Threat


The notion of a nation closing their borders to prevent the entry of a pandemic virus has been raised - and usually dismissed as impractical for most countries - many times (see Why Airport Screening Can’t Stop MERS, Ebola or Avian Flu).   
Between porous borders - and the need for most countries to import food, medicines and other important staples - the odds of maintaining an effective quarantine are believed slim.
But there are a few places on earth where such a strategy might work.  Island nations - particularly remote, relatively self-sufficient island nations -  might be able to cut themselves off from the rest of the world.  

During the 1918 pandemic, when international travel was far less common, a few nations managed to block entry of the pandemic virus by imposing a strict quarantine of all arriving passengers (see Protective Effect of Maritime Quarantine in South Pacific Jurisdictions, 1918–19 Influenza Pandemic).

The four successful quarantines during the 1918 pandemic were in American Samoa (5 days' quarantine) and Continental Australia, Tasmania, and New Caledonia (all 7 days' quarantine).
  • The Spanish Flu did not reach American Samoa until 1920, and had apparently weakened, as no deaths were reported.
  • Australia's quarantine kept the influenza away until January of 1919, a full 3 months after the flu has swept New Zealand with disastrous effects. 
  • Tasmania kept the flu at bay until August of 1919, and health officials believed they received an milder version, as their mortality rate was one of the lowest in the world.
  • By strictly enforcing a 7-day quarantine, New Caledonia managed to avoid introduction of the virus until 1921. 
Eventually, once the quarantines were lifted, the virus did make it to these isolated regions of the world. But by that time, the virus often appeared to have weakened and its impact was lessened.
While it might still be possible today, such a move would come at a high economic cost, and it still might fail. A less drastic policy - which might involve fever checking and limited quarantines at points of entry - would almost certainly miss a large number of infected travelers. 
In 2012, in EID Journal: Airport Screening For Pandemic Flu In New Zealand, we looked at a study that found that the screening methods used at New Zealand’s airport were inadequate to slow the entry of the 2009 pandemic flu into their country, detecting less than 6% of those infected.

Ten years ago, in New Zealand: Testing Pandemic Quarantine Plans, we looked at Exercise Spring Fever - a `war game' designed to test New Zealand's ability to cut themselves off from the rest of the world during a pandemic.
While no decision has ever been made regarding the quarantining of New Zealand during a pandemic, the option continues to be discussed.
Which brings us to a new study, published this week in Australia & New Zealand  Journal of Public Health, which looks at the economic impact of a 180-day quarantine on the island nation of New Zealand. 

Economic evaluation of border closure for a generic severe pandemic threat using New Zealand Treasury methods

Matt Boyd, Osman D. Mansoor, Michael G. Baker, Nick Wilson

First published: 08 August 2018

The authors have stated they have no conflict of interest.


Objective: To perform a comprehensive economic evaluation of border closure for an island nation in the face of severe pandemic scenarios.
Methods: The costing tool developed by the New Zealand (NZ) Treasury (CBAx) was used for the analyses. Pandemic scenarios were as per previous work;1 epidemiological data were from past New Zealand influenza pandemics.

The net present value of successful border closure was NZ$7.86 billion for Scenario A (half the mortality rate of the 1918 influenza pandemic) and $144 billion for preventing a more severe pandemic (10 times the mortality of scenario A). Cost–utility analyses found border closure was relatively cost‐effective, at $14,400 per QALY gained in Scenario A, and cost‐saving for Scenario B (taking the societal perspective).

Conclusions: This work quantifies the economic benefits and costs from border closure for New Zealand under specific assumptions in a generic but severe pandemic threat (e.g. influenza, synthetic bioweapon). Preparing for such a pandemic response seems wise for an island nation, although successful border closure may only be feasible if planned well ahead.

Implications for public health: Policy makers responsible for generic pandemic planning should explore how border closure could be implemented, including practical and legal frameworks.

The costs and benefits of island nations completely closing their borders to avoid or minimise the impact of a severe pandemic has received little attention in the literature. This omission may be due to doubts about the likely effectiveness of such measures, the substantial costs of implementation, and how countries interpret the International Health Regulations. Previously, we published a simple proof‐of‐concept model that suggested net benefits of border closure for New Zealand (NZ), if a generic pandemic was severe enough.1

However, limitations of our earlier approach included: not including a health system perspective; not calculating cost‐effectiveness; a lack of scenario analyses around the 3% discount rate (which is also lower than 6% favoured by the New Zealand Treasury); and only using a limited societal perspective (i.e. exclusion of the pandemic impact on productivity and superannuation payments). Our previous work also used monetised quality‐adjusted life‐year (QALY) values that were less than the values recommended by the New Zealand Treasury.

Therefore, to provide additional information for policy makers, we aimed to conduct a more rigorous cost–benefit analysis (CBA) as well as cost–utility analyses (CUA) using the New Zealand Treasury’s standardised cost–benefit analysis tool ‘CBAx’. CBAx provides a consistent approach so different government interventions can be compared.2

(Continue . . . )

Whether any of this - in our highly mobile and interconnected global society - is remotely practical, is another matter.  A quarantine would have to be enacted quickly - before any pandemic threat could make it into the country - and then the quarantine would have to be perfect in nearly every way.
While the odds of success are long, any chance of avoiding the kind of end-game scenario presented last May in the Johns Hopkins Clade X Tabletop Pandemic Exercise, is a pretty good incentive to try.  
If you haven't taken the time to watch the entire 8 hour exercise, I would urge you to view the 5 minute wrap up video. It will give you some idea of the possible impact of a severe - but not necessarily `worst case' - pandemic.

As border closing isn't an option for 99% of the world, we'll need to find other ways to deal with the next pandemic. For more on the potential impact of a severe pandemic, you may wish to revisit:
Supply Chain Of Fools (Revisited)
The Long Road To An H7N9 (or Any Other Pandemic) Vaccine

WHO List Of Blueprint Priority Diseases
FEMA PREPTalks: John M. Barry On `The Next Pandemic: Lessons from History"

Pandemic Realities: Ventilator Shortages

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