This article by a former Confessed Covidiot is all you need to show someone who refutes that natural immunity is robust and lasts for years / decades / life .

https://spectator.org/covid-not-getting-vaccinated/

There are tons of studies ( Huge Studies) which show Natural immunity to Covid is ALL you need .

With the “Variants” being so mild now…I would go so far as to say…..Don’t get Vaxxed…Get Covid !