MERS-CoV and SARS-CoV Similarities Raise ConcernsRecombinomics Commentary 13:30
May 12, 2013

The second case is affected by the coronavirus man who shared the patient's room for four days at Valenciennes, while respiratory disease had not yet been detected. For this patient and new case, which is currently hospitalized and isolated Infectious Diseases Service at the University Hospital of Lille, "the positive results have just been confirmed."
 
The above translation describes the nosocomial MERS-CoV cluster in France (see map) and highlights epidemiological similarities between MERS-CoV and SARS-CoV transmissions in 2003.  These similarities were evident in the earliest confirmed cluster, which was over a year ago in Jordan (see map).  The confirmed was made seven months after the fact and was limited to the two fatal cases, but the clustering of cases in a hospital ICU as well as subsequent transmission to family members, was strikingly similar to SARS-CoV clusters, and the initial cases were described as SARS-like.  However, initial testing was negative for coronaviruses because MERS-CoV had not been identified prior to the outbreak, and detail on the cases (age, gender, disease onset dates) has been withheld.
Although WHO did use an epidemiological study to conclude that the symptomatic cases were probable MERS-CoV cases, the number of probable cases was not cited until recently.  That update did note that two of the family members had mild symptoms and noted that there have been multiple clusters, including two family members of two recent cases in eastern Saudi Arabia.  That outbreak appears to be linked to contaminated dialysis equipment, but the confirmation of MERS-CoV in contacts supports additional human to human (H2H) transmission.  

H2H transmission was also strongly supported by the cluster in England(see map), which like the cluster in France involved infections in the Middle East which was transported to Europe by commercial airline, followed by onward transmission.  However, the cluster in England highlighted assay failures on tests of upper respiratory tract samples.  A mild case (30F) was MERS-CoV confirmed vai a PCR test of a sputum sample but the PCR test of a nasopharyngeal swab was negative for MERS-CoV, but positive for type 2 para-influenza virus (HPIV-2), which was also found in a fatal case involving the son (38M) of the index case.  The two contacts did not have contact with each other and disease onset dates were one day apart, suggesting they were infected by a common source,  However, the index case was co-infected with H1H1pdm09, which was not detected in either family members and the sister had limited contact with the index case, suggesting both cases positive for HPIV-2 and MERS-CoV were infected by another family, which was likely the daughter of the index case, who also traveled to Saudi Arabia, but was negative for MERS-CoV.  However, testing almost certainly involved a nasopharyngeal swab collected after the contact had recovered.

False negatives in upper respiratory tract samples sub-optimally collected are common and apply to the negative results for the health care workers, who were briefly hospitalized and release when they tested negative.  Similarly, the symptomatic family member was not hospitalized and also released after testing negative.
Although the number of clusters has been high (additional confirmed clusters have also been seen in earlier cases in Saudi Arabia), the false negatives have been used to claim that the cases are “sporadic” and not transmitted in a sustained manner.  However, the number of symptomatic cases in eastern Saudi Arabia has been high, and many cases, including multiple pediatric cases, have not been reported as confirmed cases (see map), raising concerns that the reported cases represent a significant undercount.
The increasing similarities between SARS-CoV and MERS-CoV raise serious pandemic concerns, and more information on the prior cases inJeddah and current cases in eastern Saudi Arabia (see map) and adjacent countries (Bahrain, Qatar, UAE), which have yet to report a single cases diagnosed locally, increases pandemic concerns.