The Catholic Church says we are to receive both if possible…
Really? You’d better go inform the German bishops conference. I lived in Germany for 4 years and never saw the chalice offered to the faithful (except once when a groups of American tourists and their American priest all tried to share the tiny priest’s chalice.)
“If any one saith, that, by the precept of God, or, by necessity of salvation, all and each of the faithful of Christ ought to receive both species of the most holy sacrament not consecrating; let him be anathema.” – Trent 21, Canon 1
“If any one saith, that the holy Catholic Church was not induced, by just causes and reasons, to communicate, under the species of bread only, laymen, and also clerics when not consecrating; let him be be anathema.” – Trent 21, Canon 2
but receiving the Body of Christ is sufficient if for some legitimate reason the person is not able to accept the Blood of Christ.
If you receive the body, then you also receive the blood, whether you receive from the chalice or not.
“If any one denieth, that, in the venerable sacrament of the Eucharist, the whole Christ is contained under each species, and under every part of each species, when separated; let him be anathema.” – Trent 13, Canon 3
"If any one denieth, that Christ whole and entire -the fountain and author of all graces–is received under the one species of bread; because that-as some falsely assert–He is not received, according to the institution of Christ himself, under both species; let him be anathema. – Trent 21, Canon 3
Some don’t take the Blood because they fear germs or don’t like wine … how would some human germ overcome the most powerful and holy Body and Blood of Christ.
It is possible to transmit communicable disease through the shared chalice.