Prevention of influenza at Hajj: applications for mass gatherings

We noted much valuable information in Haworth et al.'s paper entitled ‘Prevention of influenza at Hajj: applications for mass gatherings’. ¹ However, we wish to add a few points.

In addition to the high-risk groups identified by the authors, we suggest including healthcare personnel and pilgrims aged ≥50 years (instead of 56 years). ²

The researchers have stated that ‘isolation may be of limited value, while quarantine of contacts of a confirmed case might be considered’. ¹ Based on Centers for Disease Control and Prevention definitions, the aim of quarantine is to separate and prevent the movement of healthy persons who may have been exposed to a communicable disease to see if they become ill. Conversely, the aim of isolation is to separate patients who have a communicable disease from healthy persons. Now, the main question is how to manage this recommendation in critical conditions during Hajj? The pilgrims have been traveling primarily to perform obligatory rituals. Therefore, quarantine impractical.

Furthermore, some other non-pharmaceutical interventions may be considered: screening of high-risk individuals before the journey and preventing factors which can lead to pilgrims’ stress, fatigue and anxiety. These factors may lead to suppression of immunity. ³

Additionally, in several studies, the effectiveness of influenza vaccine was not demonstrated during Hajj. ⁴ This suggests that we should also consider the other pathogens as the aetiologic agents of respiratory problems such as adenoviruses, RSV, β-haemolytic Streptococcus, Haemophilus species, gram-negative bacilli, Legionella pneumophila and Chlamydia. ⁵