COVID-19 pandemic started because 1 person had the virus, and then it spread to a lot of others.

Now, let's say your country imposed quarantine and distancing, and you managed to halt the growth of the virus entirely.

Ok, great. But eventually you have to re-open the country again. And when you do, won't the virus just start spreading again?

I mean, it's not like the quarantine has killed the virus entirely. It still exists, it's just not spreading as quickly. So won't it just start spreading fast once you re-open the country?

  • 4
    Yes, it probably will. I suggest googling the phrase "flattening the curve" to understand why quarantining is necessary.
    – Carey Gregory
    Commented Apr 26, 2020 at 23:01
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    Have you not heard all the epidemiologists and virologists warning about this exactly if reopening occurs too soon?
    – Bryan Krause
    Commented Apr 26, 2020 at 23:50
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    Actually some countries don't have the virus or are expected to eliminate it. Commented May 29, 2020 at 6:39

2 Answers 2


The virus has actually continued to spread during the lockdowns, just at a slower pace than if no lockdown had been imposed. See for example Washington state in the USA.

The hope is that the lockdowns have reduced the spread of infections to linear or sub-linear rather than exponential growth. Linear or sub-linear growth provides an opportunity for other measures to be effective, like wide spread testing followed by contact tracing. If test and trace works, this would allow quarantine of only those who actually have the virus, or are known to have been exposed, rather than asking that everyone stay in lockdown preemptively.

It is argued that extensive contact tracing followed by targeted quarantine is what has allowed Germany, Taiwan, and South Korea to avoid the massive outbreaks seen in Italy, Spain, and the Americas. However, if the number of new infections was doubling every few days, no testing and tracing system would be able to keep up.


China and New Zealand are quarantining all returning citizens for 14 days.

That could be beefed up by antibody testing and rt-PCR if those become readily available.

That should halt the importation of the virus. And continued social distancing may be necessary for a couple of years yet.

NZ is on target to completely eliminate the virus with no new cases for some days now, current cases no longer considered infectious and the only risk being from imported cases.


  • Why would continued social distancing may be necessary for a couple of years yet? They said 12 to 18 months for the vaccine, so at most 1.5 years to stop with this measure. Commented Apr 27, 2020 at 1:02
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    @America 12-18 months are still optimistic estimates. We won't know if or when a vaccine is available until it is. If every vaccine tried fails then nothing makes one magically appear at 18 months
    – Bryan Krause
    Commented Apr 27, 2020 at 2:27

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