In the JournalsPerspective

No evidence of MERS found among hajj pilgrims

Among 5,235 pilgrims from 22 countries who performed the 2013 hajj, there was no evidence of nasal carriage of Middle East respiratory syndrome, or MERS, researchers reported in The Journal of Infectious Diseases.

Researchers from the Ministry of Health of the Kingdom of Saudi Arabia also found very little uptake of influenza and pneumococcal vaccination among the pilgrims, despite health recommendations from the Ministry of Health.

The 5,235 adult pilgrims were recruited randomly and voluntarily from queues at the airport either on arrival in Saudi Arabia (from Sept. 29 to Oct. 9) or before departure from Saudi Arabia (from Oct. 14 to Oct. 26). Trained physicians collected nasopharyngeal samples from the participants. The swabs underwent reverse transcriptase PCR testing to identify MERS coronavirus. The researchers also collected data on participants’ age, sex, country of origin and medical conditions, and also determined vaccination history using the participants’ vaccination documents.

Pre-hajj, 3,210 samples were collected, and post-hajj, 2,025 samples were collected. The vaccination documents indicated that all participants had received the meningococcal vaccine. The vaccination rate for yellow fever was 8.8%, but 100% among pilgrims from countries requiring that vaccine. The vaccination rate for polio was 43% overall, but it was 99.5% among pilgrims from at-risk countries.

Only 4.4% of pilgrims received pneumococcal vaccination and only 1.5% of people aged at least 65 years and 27.3% of those with diabetes received the vaccine. For influenza, only 22% of the pilgrims had received the vaccination, including 17.5% of adults aged at least 65 years and 36.3% with diabetes.

None of the nasopharyngeal samples tested positive for MERS. The sample included pilgrims from three of nine countries where MERS was reported (Jordan, Tunisia and United Kingdom).

“[These data suggest] low carriage and transmission rate of [MERS], although further investigations are warranted,” the researchers wrote. “International collaboration between the Saudi Ministry of Health and the different countries through the collaborative center for mass gathering and with input from WHO is being formulated to enhance the compliance with the recommended vaccinations.”

Disclosure: The researchers report no relevant financial disclosures.

Donald Kaye, MD

Donald Kaye

  • The authors are to be commended on the extent of their study. The number of pilgrims evaluated was large in terms of sheer numbers studied in such a short time. However, these numbers are insignificant in terms of looking for a rare infection. With more than one million pilgrims attending the hajj, the study size at best covered 0.5% of the pilgrims. Furthermore, the sensitivity of the test is unknown in an asymptomatic population and the rate of nasopharyngeal carriage among asymptomatic contacts in the population must be very low indeed. It would be surprising if a positive result had been found for MERS, considering that asymptomatic infection seems to be unusual, and there have been fewer than 200 cases of MERS recorded in Saudi Arabia, a country with a population of 28 million.

    The underutilization of influenza and pneumococcal vaccines is also unfortunately not surprising. It is my hope that the statistics for immunization of the US citizens in the sample was much higher than the numbers recorded for the whole group.

    • Donald Kaye, MD
    • Infectious Disease News Editorial Board member
  • Disclosures: Kaye reports no relevant financial disclosures.