It is not called the Boston Heresy for nothing. Pope St Pius X teaches Baptism of Desire and Blood in his Catchesim:
16 Q. Is Baptism necessary to salvation?
A. Baptism is absolutely necessary to salvation, for our Lord has expressly said: "Unless a man be born again of water and the Holy Ghost, he cannot enter into the Kingdom of God."
17 Q. Can the absence of Baptism be supplied in any other way?
A. The absence of Baptism can be supplied by martyrdom, which is called Baptism of Blood, or by an act of perfect love of God, or of contrition, along with the desire, at least implicit, of Baptism, and this is called Baptism of Desire.
"He that shall lose his life for Me, shall find it." (Matt. 10:39) affirms Baptism of Blood by Our Lord Himself.