Of course,* doctrinal* statements by an ecumenical council are infallible. However, SemeperFidelis is correct, that this council (according to this council) explicitly denied infallibility. Also, the popes who presided over the council both denied its infallibility. The final word on the council, and the reason it was called, would seem to deny infallibility.
John XXIII on why he’s opening.
The salient point of this council is not, therefore, a discussion of one article or another of the fundamental doctrine of the Church which has repeatedly been taught by the Fathers and by ancient and modern theologians… everything being measured in the forms and proportions of a magisterium which is predominantly pastoral in character.” (Opening Address, October 11, 1962; Walter M. Abbott, SJ, The Documents of Vatican II, p. 715)
Paul VI, on the day the closing of the council.
“Today we are concluding the Second Vatican Council. …] But one thing must be noted here, namely, that the teaching authority of the Church, even though not wishing to issue extraordinary dogmatic pronouncements, has made thoroughly known its authoritative teaching on a number of questions which today weigh upon man’s conscience and activity, descending, so to speak, into a dialogue with him, but ever preserving its own authority and force; it has spoken with the accommodating friendly voice of pastoral charity; its desire has been to be heard and understood by everyone; it has not merely concentrated on intellectual understanding but has also sought to express itself in simple, up-to-date, conversational style, derived from actual experience and a cordial approach which make it more vital, attractive and persuasive; it has spoken to modern man as he is.” (Address during the last general meeting of the Second Vatican Council, December 7, 1965; AAS 58)