So not only can "Long COVID" appear months after a person was infected... but the maximum natural anti-body immunity to re-infection disappears after 9 months... and after a mere 3 months in most people.
Experts raise concerns on long Covid symptoms appearing after six months to a year from infection
NK Arora, chief of Operations Research Group, part of the national Covid task force, also said antibodies may remain in the system for three to nine months.
https://scroll.in/latest/995360/exp...ing-after-six-months-to-a-year-from-infection
Quick Summary: Nearly 40% of people who had COVID do not develop sufficient anti-bodies to stop them from catching COVID a second time within 6 months. This aligns with other research on re-infections and the percentage of people being re-infected. Only vaccinated anti-body immunity will lead to herd immunity.
From the article:
From the analysis, the researchers created five categories based on how long antibodies lasted in an individual.
The first category, called the "negative" group, included the individuals who never developed detectable neutralizing antibodies. This group comprised 11.6% of participants.
Comprising 26.8% of patients, the second group is called the "rapid waning" group and showed varying early levels of antibodies that waned quickly. The third category comprised 29% of participants and was called the "slow waning" group as these patients tested positive for antibodies against SARS-CoV-2 for up to half a year.
The fourth group, called the "persistent" group, comprised 31.7% of patients and showed little change in their antibody levels up to 180 days. The last group, or the "delayed response" group, covered only 1.8% of subjects and included those who showed a marked rise in neutralizing antibodies during late convalescence.
Individual COVID-19 Antibodies Could Last Days To Decades, Scientists Find
https://www.ibtimes.com/individual-...uld-last-days-decades-scientists-find-3168292
Overall, we show that SARS-CoV-2 infection induces a robust antigen-specific, long-lived humoral immune response in humans
https://www.nature.com/articles/s41586-021-03647-4