There is no proof of anyone being reinfected at this point. There are less than a half dozen cases across the world which is statistical noise.
All we have is proof that people can test positive multiple times, we also have proof the current testing regiment triggers on anything remotely related to COVID, including other coronaviruses and dead remnant particles of the virus.
Viruses don't work that way, unless they mutate, you won't get re-infected unless we have the whole field of biology very, very wrong for nearly 2 centuries. COVID seems to be able to mutate very slowly, the recombinant vaccine seems to be able to capture the extant mutations.
What is possible is that someone (China) creates another form of the virus using genetic manipulation. They sent COVID in ice cream the other day while claiming their entire country has zero infections. Either they're lying about the number of infected, or they're intentionally sending COVID.
The vaccine will help, that's what vaccinations are designed to do. So will getting sick, that's what it's designed to do. Look at any other viral disease - Polio, Chicken Pox. The only way to get sick multiple times is to contract different versions of the disease. So in some cases, it may still be necessary to get polio vaccines if you already contracted polio, because there are 3 polio variants in the world and you should get vaccinated against the other 2.
COVID-19 (aka the Trump virus) is by definition 1 variant of the coronavirus, you will still get sick with the common cold which is also a coronavirus, but until there is a COVID-21 (by prior definition will be called the Biden virus), this COVID-19 vaccine (by prior definition the Trump vaccine) created by Operation Warpspeed and funded globally by the US will protect you against all currently extant variations of COVID-19.
This last notion is important to understand if you don't live in the US. ONLY the vaccines created by the Trump admin have thus far worked. China's Sinovac has a 50% efficacy (basically a coin toss whether you get immunity) and Russia's vaccine has major side effects and was cancelled. I know in the EU, Brazil and some other socialist countries you can get Sinovac or will get Sinovac, those don't work or at least not very well. Hop on a plane to Florida like every other rich person in the world to get in line for a proper distribution system. Don't go to NY where we've so far destroyed 70% of our supply because it went out of date, because NYS wants to prioritize people based on race and hasn't even started distribution to the general population yet.