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Coronavirus H2H Transmission In Riyadh Cluster
1 April 2012 45 F Jordan 30/11/12 Dead yes - hospital A
2 April 2012 25 M Jordan 30/11/12 Dead yes - hospital A
3 13/06/12 60 M KSA 20/09/12 Dead no
4 03/09/12 49 M Qatar/ KSA 23/09/12 Alive/Hosp no
5 10/10/2012 45 M KSA 04/11/12 Alive no
6 12/10/12 45 M Qatar 23/11/12 Alive no
7 3-5/11/2012 31 M KSA 20/11/12 Alive yes - family A
8 28/10/12 39 M KSA 23/11/12 Dead yes - family A
9 October 2012 not known M KSA 28/11/12 Dead yes - family A
10 24 /1/2013 60 M Pakistan/KSA 8/1/13 Alive/Hosp yes - family B
11 6/2/2013 not known M UK 12/02/13 Alive/Hosp yes - family B
As seen above, the ECDC has updated its table of confirmed beta coronavirus cases, which includes additional information on the ages of the cases as well as disease onset dates, which provide compelling data for the human to human transmission in the Riyadh cluster (cases 7-9 designated as “family A”, but in reverse chronological order).
A cluster of cases linked to a rare disease can be due to human to human (H2H) transmission within the cluster or infection by a common source. When the source is unknown, the best data for distinguishing between the two scenarios is the disease onset dates, which are still lacking for many of the cases, but the dates of death, when coupled with the known disease onset dates can be used to distinguish between a common source and human to human transmission.
The new data for the cluster on Riyadh, when combined with reliable media reports, paint a relatively clear transmission scenario for family A, which included 3 confirmed cases and 1 probable case. Media reports had indicated that the index case (70M) was the father of the second fatal case (39M), which are cases 9 and 8, respectively, in the above list. Although the disease onset date for the father is listed as October, and the son is listed as October 28, media reports indicated that father died 4 days prior to the son, supporting infection of the son by his father.
However, the most compelling data for H2H transmission in family A is the disease onset date for the surviving family member (31M, case 7, and likely another son) which is listed as between November 3-5. The disease onset time gap between the two brothers (39M and 31M) provides strong support for H2H transmission, which is further supported by the earlier date of death for the father. The fourth family member is designated as “probable” by WHO, suggesting a false negative on testing. Similar testing issues surfaced for the father, who was also initially classified as a probable case, but was subsequently confirmed.
Although the updated table includes disease onset dates which strongly support H2H transmission in family A, no disease onset is listed for the two fatal cases in Jordan (other than the month of April). These two cases were part of a larger cluster of a dozen cases linked to an ICU. The size and severity of the cluster created considerable concern. Two health care workers died (nurse, 45F and intern, 25M) while all but one of the reported symptomatic contacts were hospitalized, which included the son of the index case. The cases were described as SARS-like and samples were initially sent to labs in France and Egypt for identification of the etiology agent, signaling significant concerns.
Subsequent re-testing in Egypt (by NAMRU-3), using probes targeting the novel beta 2c coronavirus, confirmed the two fatal cases, Failure to confirm the virus in the other hospitalized cases led to a “probable” designation by WHO. The dates of death for the two confirmed cases were 1 week apart, further supporting H2H transmission within the ICU. WHO has not cited the number of probable cases in Jordan, or given disease onset dates, but like family A in the above list, it is likely that the disease onset dates for the two confirmed cases and the dozen probable cases will have significant time gaps. signaling H2H transmission.
Similarly, the third listed cluster (family B) has significant time gaps in disease onset date, and symptoms developed in two different counties (Saudi Arabia and England) further signaling H2H transmission.
These clusters, with significant gaps in disease onset dates, seriously challenge the ECDC risk assessment analysis, which ignores the probable cases and suggests that the absence of confirmed mild cases supports an animal or environmental origin.
A re-evaluation of the ECDC position (as well as a listing of the family A cases in chronological order) is long overdue.