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there are three main kinds of vaccines currently in development: one is the vaccine with adenovirus vector (sputnik, astra-zeneca). this uses a modified adenovirus (one of which also cause the common cold), which also contains rna for the the spike protein from sars-cov-2. this is probably going to provide nice antibody production because it uses alive adenovirus your immune system has to fight off. the chance of such a vaccine protecting against the common cold are minimal, but if you've been infected with a similar strain of adenovirus before the vaccine might be elimiated by already existing antibodies against that sort of adenivirus without having to recognise the sars-cov-2 spike protein at all, rendering the vaccine ineffective in such people. the second ones are the rna-vaccies (pfizer, moderna). the rna that encodes for the spike protein is shuttled into the cells using specially designed lipid nanoparticles. since the infected cells are also going to produce the spike protein until they're cleared by the immune system, we can expect good immunogenicity here, even though you have nothing replicating in your body. in principle rna-vaccines combine the positives from live and inactivated vaccines, but up to date no rna-vaccine has ever been approved for humans so there's a risk for unknown side effects. the third ones are "classical" inactivated vaccines (sinovac), where the virus is grown in cell culture (no dead animals involved, it'd probably be a human cancer cell line that has been used in labs for decades) and then inactivated using chemicals (and probably heat). the advantage is that it cannot replicate inside the body, gives the immune system a chance to "look at" the whole virus, but on the downside all the antigens your body will ever see are inside the syringe of the vaccine already. so the immune response is most likely going to be weaker. there's no "double jeopardy" here. if the virus mutates in one of a few particular ways that change the spike protein, your immune system will not recognise the new virus and have to start fresh with producing antibodies. but it doesn't matter if you've had the disease before or the vaccination. a small concern i have here is that theres a small chance that some mutations in the virus might have old antibodies trigger a potentially dangerous overreaction from the immune system (as we see with dengue fever. if you're infected with one strain you have an unpleasant but managable disease and you're immune to that strain forever. if you however get a different strain than the one you've had before you're in for a really bad time). however this would also be of more concern for people who've had covid-19 before than vaccinated people because antibody levels would most likely be higher in the former group. yeah, polio outbreaks from vaccination are real (in the few areas where not everyone is vaccinated), but since we're 99% there to eradicating polio forever it's a small price to pay. just like no one would want to return to a world where smallpox was still around. the smallpox vaccine was more dangerous than pretty much any vaccine we use today. sure, in our age group there's a >99% chance that you'll survive the virus. and even a 2 in 3 chance you'll not get more sick than with the flu. but still in all age groups there's a ca. 5-10% chance for suffering long term consequences (including chronic fatigue for months, dizzyness, drop in iq of nearly 10 points, high blood pressure, and in some rare cases heart failure or demyelinisation (think multiple sclerosis)). a friend is currently doing a study on post-covid changes in the brain and while it's too early to say anything definitely, he has seen activation patterns commonly associated with depression in the great majority of test subjects. also only a small proportion of subjects (even those who had mild disease) report feeling 100% healthy even after months. this virus is no joke and we will only realise the full impact of this pandemic in the coming year.