If lamb shift is really due to the effect caused by virtual particles how come it only affect 1 orbital?

I was watching a video explaining virtual particle can be drawn to the positively charged necleus which explain why there is a tiny step between the higher energy level and ground state, but I'm not convinced as to why it doesn't affect all other energy levels?

• The Lamb shift does affect other orbitals - it just does so at higher orders of perturbation theory. There are more details at Why is the energy of $2s_{1/2}$ greater than the energy of $2p_{1/2}$ after the Lamb shift is taken into account?. Jan 4 '19 at 17:12
• "lambshift" ... ? Jan 4 '19 at 17:30
• @my2cts Yes that is a typo, but I'm sure you know what they mean. Jan 4 '19 at 20:52
• @Aaron Steven For a brief moment I believed that they mistake "Willis Eugene Lamb Jr. (July 12, 1913 – May 15, 2008) [ ] an American physicist who won the Nobel Prize in Physics in 1955 "for his discoveries concerning the fine structure of the hydrogen spectrum.", for livestock. en.wikipedia.org/wiki/Willis_Lamb Jan 4 '19 at 21:08