The fight against the spread of the 2019-nCoV epidemic has achieved some success in China, but the epidemic is far from over. A key factor making the epidemic under control in China is the government's call for social distance, which has led to few people going out for donation. As a result, the number of blood donors on the streets has been continuing to decline. The first urgent recruitment of blood donors had been implemented during the period from 30 April to 10 May via emergency recruitment SMS . This repeat trial has been designed to further confirm the results from the the first recruitment by comparing which information extraction frameworks would be more sensitive to blood donors in emergency situations.

Researches has showed that that the information extraction and processing in emergency was different from the normal situation. To understand what information the blood donors are more sensitive to in an environment that may pose a potential threat to themselves, the first urgent recruitment of blood donors had been implemented during the period from 30 April to 10 . This interventional study is the repeat trail of the first trail. The same with first trail, eligible blood donors in Guangzhou Blood Center has been randomly divided into four groups according to their sociological variables, their interval since last blood donation , their history donation times and the location of their last blood donation. Three groups of donors has been randomly selected as interventional groups, and will receive three kindly of emergency blood donor recruitment SMS respectively. The placebo group donors will only receive a thank-you SMS. One recruitment SMS will emphasize what blood services will do to ensure the safety of blood donors during their donation in 2019-nCoV epidemic,one will shows information about a loss-based framework, while the third one will show information about a benefit-based framework .

Inclusion Criteria:

• Blood donors whose last turning up were between November 31, 2016 to November 31, 2019

Exclusion Criteria:

• Blood donors who were deferral by blood screening result and other situations. Blood donors who have indicated that they would not accept urgent recruitment.