Published time: 28 August 2014
Authors: Christian Drosten, M.D., Benjamin Meyer, M.Sc., Marcel A. Müller, Ph.D., Victor M. Corman, M.D., Malak Al-Masri, R.N., Raheela Hossain, M.D., Hosam Madani, M.Sc., Andrea Sieberg, B.Sc., Berend Jan Bosch, Ph.D., Erik Lattwein, Ph.D., Raafat F. Alhakeem, M.D., Abdullah M. Assiri, M.D., Waleed Hajomar, M.Sc., Ali M. Albarrak, M.D., Jaffar A. Al-Tawfiq, M.D., Alimuddin I. Zumla, M.D., and Ziad A. Memish, M.D.
Keywords: MERS-Coronavirus, transmission.
Strategies to contain the Middle East respiratory syndrome coronavirus (MERS-CoV) depend on knowledge of the rate of human-to-human transmission, including subclinical infections. A lack of serologic tools has hindered targeted studies of transmission.
We studied 26 index patients with MERS-CoV infection and their 280 household contacts. The median time from the onset of symptoms in index patients to the latest blood sampling in contact patients was 17.5 days (range, 5 to 216; mean, 34.4). Probable cases of secondary transmission were identified on the basis of reactivity in two reverse-transcriptase–polymerase-chain-reaction (RT-PCR) assays with independent RNA extraction from throat swabs or reactivity on enzyme-linked immunosorbent assay against MERS-CoV S1 antigen, supported by reactivity on recombinant S-protein immunofluorescence and demonstration of neutralization of more than 50% of the infectious virus seed dose on plaque-reduction neutralization testing.
Among the 280 household contacts of the 26 index patients, there were 12 probable cases of secondary transmission (4%; 95% confidence interval, 2 to 7). Of these cases, 7 were identified by means of RT-PCR, all in samples obtained within 14 days after the onset of symptoms in index patients, and 5 were identified by means of serologic analysis, all in samples obtained 13 days or more after symptom onset in index patients. Probable cases of secondary transmission occurred in 6 of 26 clusters (23%). Serologic results in contacts who were sampled 13 days or more after exposure were similar to overall study results for combined RT-PCR and serologic testing.
The rate of secondary transmission among household contacts of patients with MERS-CoV infection has been approximately 5%. Our data provide insight into the rate of subclinical transmission of MERS-CoV in the home.
Transmission of MERS-Coronavirus in Household Contacts