<strong>Latest: <a href="https://www.thenational.ae/uae/health/coronavirus-gulf-drives-down-cases-but-rest-of-middle-east-struggles-with-dire-second-wave-1.1068544">Gulf drives down cases but rest of Middle East struggles with dire second wave</a></strong> Abu Dhabi introduced mandatory Covid-19 testing for people entering the emirate at the <a href="http://www.thenational.ae/uae/transport/coronavirus-how-does-abu-dhabi-s-new-border-system-work-1.1041777">end of June</a>. Drivers and passengers were only granted entry to the capital if they could present a negative Covid-19 test taken within a specific time period. Since then, the details have changed a few times. Initially, only polymerase chain reaction (PCR) swab test results were accepted but later people were allowed to enter with results from a cheaper diffractive phase interferometry (DPI) laser test, which cost just Dh50. Now, the emirate has updated the rules allowing people to enter using only a DPI test. However, on the sixth consecutive day of entry to Abu Dhabi, a negative PCR test received within 48 hours must also be presented. <span>So what does the change to the system mean for motorists?</span> <em>The National</em> explains. Residents and Emiratis driving into Abu Dhabi will need a negative PCR or DPI test result received within the previous 48 hours to be granted entry. The DPI laser test is valid on its own but can only be used to enter the emirate for five consecutive days before a negative PCR result, received within 48 hours, is also needed. Alternatively, people can present a negative PCR result without a DPI test. “Residents and visitors can enter the emirate of Abu Dhabi within 48 hours of receiving a negative PCR or DPI test result. DPI test results no longer require a prior PCR test,” the Abu Dhabi government media office tweeted. “Residents and visitors who stay for six consecutive days or more within Abu Dhabi emirate must now take a PCR test on the sixth day of each visit, in order to protect the health and safety of the community.” The rapid test costs Dh50, while the PRC swab is typically Dh370. The cheaper DPI test is more popular among regular commuters. However, it does not determine if the person tested has Covid-19, rather only checks for a surge in blood cells that indicates some kind of infection. Daily commuting is not encouraged by authorities but if a person's job depended on it, it is possible. It is part of strengthened measures to curb the spread of Covid-19. Authorities said cases had been steadily rising since August with the UAE recording its highest number of daily cases (735) since May on September 2. The PCR<strong> </strong>test is considered the "gold standard" for Covid-19 diagnosis. It works by taking a sample from the throat or nose. Scientists then strip it down in a laboratory to detect the virus's genetic material. This test is more laborious, and expensive, at about Dh370. For the laser test, medics take a drop of blood that is analysed using a laser beam of light. It looks for changes in blood cells. A healthy person’s blood cell is perfectly round, but scattered in unhealthy cells. The image is then compared to thousands of others using an algorithm. The team behind the device said it proved 85 to 90 per cent accurate in tests.