It was impossible after we learned a few things: -R0 was quite high -Animals can hold and spread the virus, so even after vaccinations of humans it was going

It was impossible after we learned a few things: -R0 was quite high -Animals can hold and spread the virus, so even after vaccinations of humans it was going to be in the background -not every country was trying for zero Covid, therefore at some point in the future if you ever hope to have an open border with a country that has open borders with that country, you get it eventually. -there are no 100% secure borders