Early effectiveness of heptavalent conjugate pneumococcal vaccination on invasive pneumococcal disease after the introduction in the Danish Childhood Immunization Programme. - Harboe ZB; Valentiner-Branth P; Benfield TL; Christensen JJ; Andersen PH; Howitz M; Krogfelt KA; Lambertsen L; Konradsen HB (Vaccine, 2010)