Seventeen airport workers have tested positive for COVID-19 in Nanjing, capital of East China's Jiangsu province, as of noon on July 21.

The cases involve airport ground service workers and cleaning staff, which tested positive during a regular nucleic acid test at Nanjing Lukou International Airport. Nine of the workers had been diagnosed as confirmed cases, eight as asymptomatic carriers, and one had been found infected with the Delta variant.

Nanjing had begun testing all of its 9.3 million residents for COVID-19 since Wednesday and upgraded 10 of its communities from low- to medium-risk for COVID-19 as of Thursday morning.

To strengthen COVID-19 prevention and control in the city, Guangzhou Center for Disease Control and Prevention reminds residents to abide by the following measures:

1. People traveling or returning to Guangzhou from Nanjing in the past 14 days (on and after July 7) should report to their community (village) committee and comply with health management measures.

2. Those who develop symptoms like a fever or cough should avoid taking public transport, check in at a nearby clinic, wear masks in public at all times, and truthfully inform healthcare workers of their travel and epidemiological history.

3. Don't travel to Nanjing unless you have an emergency situation.

4. Maintain vigilant and keep taking personal protective measures. Continue to wear masks, wash hands frequently, maintain good indoor ventilation, avoid groups, follow social distancing guidelines, cover your mouth and nose when coughing and sneezing, use serving chopsticks, and practice good personal hygiene.

5. As a measure to protect yourself and your family, it is advised to get fully vaccinated as soon as possible.