Exemptions do pose a small risk, especially early exemptions lowing for early exemptions which may release highly contagious cases into the community. Therefore reducing interpersonal contact within the government quarantine facility is essential.

Northwestern University

7 scenarios were mathematically modeled in order to predict what the pandemic will look like New Zealand once border reopen.
- Scenario 1: Test on Arrival Only
- Scenario 2: Test on Arrival and Departure
- Scenario 3: Five Day Quarantine 
- Scenario 4: 10 Day Quarantine 
- Scenario 5: 14 Day Quarantine (Currently being employed)
- Scenario 6: Exemptions Allowed
- Scenario 7: Late Exemptions Allowed

7 Scenarios

Steyn N., Binny R., et al. The effect of border controls on the risk of COVID-19 reincursion from international arrivals. 22 July 2020. BioRxiv. https://doi.org/10.1101/2020.07.15.20154955

The effect of border controls on the risk of COVID-19 reincursion from international arrivals

Extending the quarantine to 10 days is equivalent to 1 highly infectious case being released into the community every 100 days on average.

Scenario 4 Model

A 5-day quarantine period detects as many cases as the full 14-day period but is not as effective in preventing highly infectious cases reaching the community. A 5-day quarantine leads to 6.8% of arrivals who are highly contagious being inappropriately released. This is equivalent to 1 case reaching the community every 9 days. 

Scenario 3 Model

Testing only upon arrival and departure detects 64% of arriving infected cases.

Scenario 2 Model

Testing only upon arrival only detects 53% of arriving infected cases. 

Scenario 1 Model

Extending the quarantine to 14 days (which is the current policy) equated to 1 highly infectious COVID-19 case being released into the community every 600 days. If interpersonal contact is allowed within the quarantining facilities, this risk can rise to 1 every 27 days, which is why separating people during quarantine is essential.

Scenario 5 Model

Scenario 6 Model

Late exemptions (in the second week only) pose less of a risk since the individual has been quarantined for a significant amount of days already. 

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