Signs No Longer Point to Pandemic

MERS virus pandemic concerns eased in new study

(RxWiki News) MERS, the latest virus to spark global concern, has had health officials worldwide nervous about possible widespread outbreaks. But new research may ease concerns.

A recent study examining cases of MERS-CoV (Middle East respiratory syndrome coronavirus) has found that the likelihood of a MERS pandemic is low.

"Sneeze and cough into a tissue."

This new French study, led by Romulus Breban, PhD, of the Emerging Diseases Epidemiology Unit at the Institut Pasteur in Paris, examined the likelihood of MERS developing into a pandemic affecting large numbers of people and regions.

Viruses are generally considered epidemic when they affect more people than expected at a given point in time. Viruses are considered pandemic when they spread on a widespread and global level, for example, across various continents. 

In the latest counts, published on July 7, the World Health Organization (WHO) reported a total of 80 confirmed cases of MERS globally since September 2012, the majority of which have occurred in Saudi Arabia. A total of 44 cases have resulted in death.

MERS is from the same family of viruses as severe acute respiratory syndrome (SARS), which caused hundreds of deaths when it developed into a pandemic in the early 2000s.

According to the study authors, the two viruses are also similar in traits such as airborne transmission, high percentage of fatalities and predominantly respiratory symptoms. 

For their study, Dr. Breban and team examined 55 of the earlier MERS cases, using data published by the WHO. The group of patients studied were 74 percent male and had an average age of 56. Of these cases, 59.4 percent resulted in death. 

The authors used this information to estimate the basic reproduction number of MERS-CoV and compared it to that of the SARS virus before it became a pandemic.

The basic reproduction number represents the number of people in a population susceptible to the virus who should become infected when exposed to an infected person. A score greater than 1 warns that potential for an epidemic of the virus has already been reached. 

Dr. Breban and team calculated their data using two different scenarios, one being the best possible situation and one being the worst.

For the worst-case scenario, the basic reproduction number was estimated to be 0.69. For the best-case scenario, it was estimated to be 0.60.

Both of these scores were under the general epidemic score of 1 and the pre-pandemic score for SARS, which was found to be 0.80.

"Our analysis suggests that MERS-CoV does not yet have pandemic potential," the authors concluded. However, they still urged caution.

"We recommend enhanced surveillance, active contact tracing, and vigorous searches for the MERS-CoV animal hosts and transmission routes to human beings," wrote Dr. Breban and team.

The WHO also reported on the need for vigilance from healthcare providers and travelers returning from the Middle East who develop severe acute respiratory infections.

This article was published online in The Lancet on July 5.

No conflicts of interest were reported. Funding for the study was provided by the French government and the European Community's Seventh Framework Programme.

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Review Date: 
July 7, 2013