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People wait for samples to test COVID-19 in Da Nang – Photo: TRUONG TRUNG
Positive then negative for two days
Specifically, this case is that of Mr. PNS (64 years old, living in Hoa Hai Ward, Ngu Hanh Son District, Da Nang City). On September 5, Mr. S. had a fever and cough, so he went to the emergency room at Da Nang C Hospital.
At 7:30 p.m. on September 5, Hospital C took a sample to test COVID-19, on the morning of September 6, to obtain a positive result.
On the morning of September 6, Hospital C continued to transfer the samples collected at 7:30 p.m. on September 5 to the City Center for Disease Control (CDC) for analysis, the results were positive. Mr. S. was transferred to the Hoa Vang Field Hospital.
On September 6, the technician from Hoa Vang Hospital (at 8:45 a.m.) and the CDC technician from Da Nang (at 9:00 a.m.) took samples and retested Mr. S. to send to the CDC. Da Nang for the test, the results of both samples are negative for SARS-CoV-2 by the RT-PCR method.
On the afternoon of September 6, samples continued to be taken from Mr. S. for antibody testing using the rapid test method and the Mac Elisa method, and the results were positive for antibodies (i.e. the body of the Mr. S. used to be infected with viruses before (SARS-CoV2, but currently his test result shows that he is negative for SARS-CoV-2).
In a CDC Danang laboratory – Photo: TRUONG TRUNG
Needs a more professional opinion
The Da Nang Health Department also provides information on the epidemiological investigation of Mr. S. Specifically, Mr. S.’s brother received a rapid antibody test from Hospital C, the result was positive, while the previous RT-PCR test on August 15 was negative.
His wife S. received a rapid antibody test from Hospital C, positive results and a PCR test using RT-PCR on September 5 came back negative.
Patient’s daughter is teacher, exam officer, she was tested before high school exam, CDC tested Sept 1-9 by RT-PCR method and gave negative results.
When there was information that a patient tested positive for SARS-CoV-2 at Hospital C, the family members were transferred to medical isolation at the Ngu Hanh Son District Medical Center.
On the afternoon of September 6, the Mac Elisa method antibody test results of the patient’s brother, wife and daughter were positive, meaning that in the past he had been infected with the SARS-CoV virus. two.
The results of the antigen test using the RT-PCR method of 6 family members, the sister-in-law of 1 patient, and 3 other related individuals were negative for SARS-CoV-2.
“Based on the test results, show the patient has a positive antibody test result, that is, the patient has been infected with the SARS-CoV-2 virus in the past. Currently, the test results show that a patient negative for SARS-CoV-2 means that the patient is not infected with the virus.
This is the case when it is necessary to have more scientific basis and professional opinion. The Da Nang City Health Department will report to the Health Ministry for professional guidance and direction in handling this case, “the Da Nang Health Department reported.
The Da Nang Health Department also said it had implemented anti-epidemic measures in accordance with regulations; Patients are isolated, treated and will continue to collect antigen samples by RT-PCR in the coming days.
The health sector has also investigated cases of close contact with patients, medical isolation, antigen sampling using the RT-PCT method, all test results are negative for SARS-CoV-2. (10 cases as mentioned above).
How are the two test methods different?
RT-PCT antigen assay: la test method intended to find antigens (pathogen – SARS-CoV-2 virus) present in the body and potentially infectious at the time of sampling.
Antibody test – This is a test method intended to find antibodies. When we have a disease caused by a pathogen such as bacteria, a virus … (antigens), the body produces antibodies in response to that antigen.
The antigen test is to determine at the time of the test, whether the body is infected with the antigen or not. An antibody test looks for antibodies, which are produced when the body has received an antigen.
