No it lowers the risk of severe illness and with the latest variants that reduction in severe illness is 40%. It is a bit better after a natural infection.
"Researchers observed that BNT162b2 PD3 immune sera neutralised USA-WA1/2020, BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and XD-spike (Deltacron) SARS-CoV-2 with geometric mean titres (GMTs) of 1,335, 393, 298, 315, 216, 103, and 301, respectively. All PD3 sera neutralised all variant-spike SARS-CoV-2 with neutralisation titres of > 20. However, neutralising GMTs against BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and XD-spike SARS-CoV-2 were 3.4-, 4.5-, 4.2-, 6.2-, 13.0-, and
4.4-fold lower than that against USA-WA1/2020 GMT, respectively."
"On the other hand, sera from BA.1-infected individuals neutralised USA-WA1/2020, BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and XD-spike viruses with GMTs of 15, 430, 110, 109, 102, 25, and 284, respectively. Thus, the neutralising GMTs against heterologous USA-WA1/2020-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and XD-spike SARS-CoV-2 were 28.7-, 3.9-, 3.9-, 4.2-, 17.2-,
and 1.5-fold lower than that against homologous BA.1-spike virus, respectively."
So against the B4/5 variants that are causing the present outbreal a 4.4 times lower efficacy if vaccinated and a 1.5 lower efficacy from natural infection.
And i have known folks with severe illness after having 4 shots.