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There are now two COVID-19 vaccines approved for use in the United States, with a third on the verge. All of these vaccines have roughly 95% effectiveness, and prevent severe COVID cases 100% of the time. Meaning we're now on track to end the COVID pandemic.

But only if we can build enough herd immunity through a combination of the vaccine, and people who have natural immunity through infection. But how many people will need to get vaccinated before we can get the pandemic put down?

The number for herd immunity on any virus or disease is based on how effectively the illness can spread, or R0 (or R naught), of the illness. Which is the scientific way to quantify how many people an ill person will infect while they're contagious. You have to keep that number in mind while working to figure out how fast you can beat any illness.

As Zach Nayer at StatNews explained it last month:

"If R0 is 4, then 75% of the population needs to acquire immunity to the virus in order to halt transmission."

So to achieve herd immunity, you need to get enough people who have either recovered from the illness (in our case, COVID-19) or have been vaccinated so that the virus cannot spread through those people anymore. Basically building a shield around those who could still be infected. If the virus has roadblocks put up in the population, it can't move a freely.

Currently, COVID-19's R0 is just over 1% (somewhere between 1.2% and 1.5%) over the last month. This would mean that the level of vaccination needed for herd immunity to COVID-19 is lower than the exercise above with an R0 of 4. In the above exercise, we would need 75% of the population vaccinated (or recovered) to stop the spread. Which would put the rates for an R0 of 1.5% even lower.

Again, going back to the stats put together by Zach Nayer at StatNews, with these levels, we could achieve herd immunity through vaccinations by May of this year. That's right, full herd immunity, and the end of the pandemic, by May.

So how do we get there? That would mean we need just 64% of the population to be vaccinated by that point. A number that should be VERY easy to hit if our nation wanted to.

If we only reach 39% of the population vaccinated by May, we could be looking at a much longer build to herd immunity. That would push back the defeat of the pandemic to December of this year.

So at this point, the end is within reach. But it will be up to governments, healthcare providers, and the public to get the vaccinations out as fast as possible to get us there. We know we could be done by May, but only if we want to.