Hypothetical question: if everyone receives the vaccine except for me, an I not safe? Who could I catch the virus from and whom could I transmit it to?
Meanwhile, the Chicoms are brewing up something new in their Wuhan witches' kettles.
First, some context: not everyone else CAN receive vaccines. Many cancer patients, for instance, can't have vaccines because their immune system is so completely destroyed that it a) would do them no good and b) could cause severe reactions because of the specifics of how their cancer treatment is affecting their body. Anyone with an autoimmune disorder may be unable to take them. Pregnant women can't take them. Children under certain ages can't take certain vaccines. Every single medicine ever developed has SOME people who can't take it. Vaccines are no different.
Now, if everyone else except you, plus everyone else who objects to taking it, plus everyone else who CAN'T take the vaccine, is still greater than the herd immunity threshold, then we're still fine. In other words, if the herd immunity threshold is 70% and 10% can't take the vaccine and 5% refuse it, we're at 85%, which is over 70%. However, if the HIT is 85% and 10% can't take it and 10% refuse it, we're at 80%. That's below herd immunity. Now the people who CAN'T take the vaccine (cancer patients, pregnant women, young children, etc.) are at risk for catching the disease. Those people already have compromised immune systems, so they're at much greater risk for complications than otherwise health individuals. So in that case, you and the other 20% of people who haven't had the vaccine can catch and transmit the disease. That is the concern.
Speaking specifically about COVID-19, the upper end of the likely R0 for SARS-CoV-2 is 3.8. HIT is 1-1/R0, so that gives us 73.7%. That's pretty much our worst case scenario for herd immunity. It's likely a bit lower than that (possibly as low as 54.5%.) The specifics of the vaccine(s) approved will tell us how many CAN'T take it. After that, we will have to see how many refuse to take it to see whether that choice leaves enough of a gap that COVID-19 can continue to spread for some people of time before herd immunity is reached. Hopefully, the objections are limited and we very quickly have enough people vaccinated that we hit herd immunity and this whole mess ends. The higher we get our total population immunity percentage, the faster COVID-19 vanishes. I want that. President Trump wants that. I should hope we would all want to see that.