Among the patients who were immunized with meningococcal MCV4P, how many have viral sinusitis disorder after getting the immunization?
immunized with meningococcal MCV4P refers to DESCRIPTION = 'meningococcal MCV4P' from immunizations; viral sinusitis disorder refers to DESCRIPTION = 'Viral sinusitis (disorder)' from conditions;
SELECT COUNT(DISTINCT T1.patient) FROM immunizations AS T1 INNER JOIN conditions AS T2 ON T1.patient = T2.PATIENT WHERE T1.DESCRIPTION = 'meningococcal MCV4P' AND T2.DESCRIPTION = 'Viral sinusitis (disorder)'