Contact tracing , including contacts in household ,workplace, school and social settings.
Careful history should be taken with regard to the timing of contact with sick individuals and the onset of illness.
Contacts should be tested with reverse transcription polymerase chain reaction (RT-PCR)and acute and convalescent serology if they became symptomatic.
Complete investigation of asymptomatic contacts, including testing for rRT-PCR and acute and convalescent serology , would best be done as areseach protocol.