It would seem not, because baptized infants haven't yet received the Eucharist (at least in the Roman Rite), yet nobody suggests they are not saved. The same would apply to a catechumen who were baptized and dropped dead immediately, such that there was no time or opportunity to give him Viaticuм.
This is not to suggest that someone beyond the age of reason, who has the opportunity, and who has been taught what the Eucharist is, should forego receiving communion indefinitely.