Write SQL query to solve given problem: Among the patients who were immunized with meningococcal MCV4P, how many have viral sinusitis disorder after getting the immunization?. Keep the solution inside sql tag ```sql [SQL-Query] ```
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)'