The Church has always taught that Catholics do not sin when they are unable to come to Mass for "grave cause" or "serious reason." This includes illness, care of others, remoteness or unavailability of Mass for a number of reasons.
In these cases the Church encourages us to make an act of “spiritual communion,” where we unite ourselves to God through prayer. It is a beautiful way to express to God our desire to be united with him when we are unable to complete that union in the reception of Holy Communion.
My dear Jesus, I believe that you are present in the most blessed Sacrament. I love you above all things, and I desire to receive you into my soul. Since I cannot at this moment receive you sacramentally, come at least spiritually into my heart. I embrace you as if you were already there and unite myself wholly to you. Never permit me to be separated from you. Amen.