you could always go the rms route and refuse to use anything besides smtp plus wget+lynx. Unlikely to get viruses that way.

https://www.pcdecrapifier.com/

(caveat: I haven't used it. cuz I use linux)

@bja I bet if you insisted on using haiku for all of your day to day programming you could achieve "security through obscurity" for a while against viruses https://www.haiku-os.org/