Data up to 7th round of Citywide NAT and Key Groups NAT show continuous decrease in community infections

In order to prevent the transmission risk of COVID-19 in Macao, the Novel Coronavirus Response and Coordination Centre (hereinafter referred to as the “Center”) had announced to carry out a Citywide Nucleic Acid Testing Programme from 12:00 on 19 June. As of 12 July, 7 rounds of mass NAT testing have been conducted. The following is a summary of the past citywide testing and key groups testing drives:

Upon the conclusion of the 3rd round of citywide nucleic acid test, Macao has undergone 5 days of rapid antigen testing (RAT) consecutively. In the 4th round of the Citywide NAT, a relatively large number (94 tubes) of mixed samples were found to be positive, which was consistent with the expectations; this is because rapid antigen testing (RAT) can only detect people with higher viral loads, but not those with lower viral loads.

Starting 4 July, Macao continued to carry out mass nucleic acid testing for the general public and key population groups every two days (i.e. Round 4-7). According to the test data, the number of positive mixed samples found in each round has been decreasing, from 94 tubes in Round 4, to 41 tubes in Round 5, and then to 23 tubes in Round 6. In Round 7 which was closed on 11 July, the figure has already dropped to 17 tubes (See Annex). This is evidence that continuous mass testing is effective, and can facilitate early detection, isolation and treatment for infected persons. Coupled with epidemiological investigations, reduced mobility and crowd gathering, as well as other measures, the number of community infections has continued to decline.

However, due to the incubation period of infectious diseases, it is not possible to identify all infected persons with a single nucleic acid test. It is hence necessary to conduct several tests in a row to find out the hidden cases that were still in the incubation period in the previous round.

The Centre also noticed concern among some members of the public regarding an increase in the number of cases detected in the community on 11 July (24 cases) as compared with the day before (17 cases). It must be pointed out that although each round of mass testing begins at 09:00, the test results usually come out in the afternoon. When a mixed sample is found to be positive, it is necessary to contact the relevant person for a single-sample test. Therefore, many positive cases are diagnosed towards the end of the first day, and more often on the second day, which resulted in a greater number of people being found positive in the second day of the citywide and key groups testing.

With regard to case classification (i.e. cases found in community or cases found under management and control), currently in Macao, close contacts, positive cases detected through citywide and key groups testing, cases tested positive in rapid antigen test, and cases detected by other screening channels are all classified as cases found in the community.

Annex: Number of positive mixed samples detected in Citywide NATs and Key Group NATs