That is for the current strand of COVID-19. When winter comes, the virus will have changed into a new strand. You will need different antibodies. Plus, New York city population is in constant flux. They will never achieve herd immunity. Hence the vaccine problem. It needs to be updated every year just like the flu vaccine for the year's flu virus. So, scientists are currently playing a catch up game with COVID-19. The virus is about two steps ahead. It could morph into a weaker virus or a stronger virus. It is an RNA sequence, not DNA.
RNA viruses generally have very high mutation rates compared to DNA viruses, because viral RNA polymerases lack the proofreading ability of DNA polymerases. This is one reason why it is difficult to make effective vaccines to prevent diseases caused by RNA viruses - diversity is their strength. The flu virus is also RNA.
