Did you mean to say that previously-infected have much less resistance than the vaccinated? I would very grateful for a source on that. I tried to find out numbers on that but couldn't find apples-to-apples comparison.
I'm saying that the previously infected w/o a vaccination are more likely to get reinfected that those who were infected and then get vaccinates: about 2.34x as likely. Reinfection rates are low [0]
The risk of reinfection if not vaccinates may also be higher than the risk for an initial infection if vaccinated: Reinfection rates are about 0.31% [1] and as high as 0.7% in some populations [2] while infection rates among vaccinated are about 0.18% [3]
[0] https://www.cdc.gov/mmwr/volumes/70/wr/mm7032e1.htm?s_cid=mm...
[1] https://jamanetwork.com/journals/jamainternalmedicine/fullar...
[2] https://medicine.missouri.edu/news/study-finds-covid-19-rein...
[3] https://www.medpagetoday.com/special-reports/exclusives/9392...