Eight of the patients numbered 2404-2412 were already in quarantine and the ninth was detected during a province-wide testing campaign.
With two cases confirmed in the morning, Hai Duong has recorded 11 cases Wednesday.
The province leads in the number of community cases recorded since January 28 at 636, followed by Quang Ninh (61), Ho Chi Minh City (36) and Hanoi (35).
The national Covid-19 tally stands at 2,412, with 1,790 recoveries and 35 deaths. Thirty recoveries were announced Wednesday.
Most of the active patients are in stable health, with 191 having tested negative for the novel coronavirus at least once.
Ten containers with 117,600 Covid-19 vaccine doses produced by the AstraZeneca companyarrived at HCMC’s Tan Son Nhat International Airport Wednesday morning.
Covid-19 has claimed nearly 2.5 million lives globally.