And happy she made a good recovery.

Hi Soufie Both infection and vaccination stimulate adaptive immunity which produces memory B cells , Killer T cells and neutralising antibodies that determine how robust and prolonged an immune response is .

There are many different vaccine platforms . Each uses a different approach to trigger adaptive immunity .

For example ..,, mRNA vaccines do NOT contain the COVID VIRUS , they contain instructions to teach the immune system to recognise the covid spike protein and activate an immune response .
As All coronaviruses have the spike protein in common, in theory mRNA vaccination will enable the immune system to be able to detect the spike protein of different covid strains . (That is quite remarkable , if it is correct ) . However , there is already evidence that covid variants can have genetic mutations to the spike protein which allow the virus to go unrecognised /undetected by the immune system.

In comparison ... immunity initiated by infection may only be effective against the initial strain it was exposed to (similar to how a flu virus behaves ). That response is also dependent on a number of factors but in particular the level of infection sustained . A severe covid infection likely produces a more robust immune response compared with a mild infection .

How long protection lasts is still hard to predict . There has not been sufficient large scale studies (or time passed ) to provide conclusive evidence .(covid vaccines in Uk only began in dec 2020) .
For now the duration of protection against infection is considered unlikely to be ......
beyond 12 months (post-natural infection).
Or beyond 6 months (post current vaccinations ) . Which is why a third booster shot for Pfizer is underway . Likely annual vaccination will follow that . As each month passes it may become clear there is evidence of a more prolonged immune response but for now that is inconclusive.

A small study showed that those with prior infection who had also been vaccinated had a stronger , more prolonged immune response

At this stage what is becoming clear .... .
Infection with one strain of covid does not guarantee that an individual will not be reinfected .
The current covid vaccines are not a guarantee of complete protection against the virus , or lifelong immunity .

Does that help lol . Hope both you , Kristi and Di stay fighting fit ., the forums would crumble without you xox

Hi crystal . If the immune system has been exposed to an infection . That by no means guarantees permanent immune protection . It could mean however that reinfections will be less severe . . Viruses especially are problematic for the immune system . If you consider a viral infection such as Epstein Barr , cytomegalovirus or herpes ... reinfections do occur . Many viruses can lay dormant in the body and resurface when resistance is low . We don’t yet know if covid has that ability . Definitely there are some situations where immunity from infection appears to be longterm but that is by no means applicable to every infection .