Anyone who was on bus route 22N from central Auckland to Avondale on August 12 is being urged to contact health authorities after two people with Covid-19 rode on the bus.
The two passengers, one of whom is believed to have caught the virus from the other, took the bus from Symonds St Overbridge (Stop 7162) to Avondale (Stop 8200) between 10.30am and 1.04pm on August 12, the day Auckland went into level 3 lockdown.
Auckland Regional Public Health Service (ARPHS) says there were 16 other passengers who travelled the same route, plus the driver.
"Of those people, ARPHS has identified 11 as close contacts. Nine of these people are being contacted by the National Investigation and Tracing Centre with advice on self-isolation and testing."
The remaining two people did not use registered AT Hop cards.
"Because of this, we do not have their contact details," the health service said.
"Our advice is that anyone who knows that they took the same bus as the confirmed cases between 10.30am and 1.04pm on Wednesday August 12 should self-isolate, call Healthline (0800 358 5453) for advice and get tested as soon as possible.
"A further five people who travelled on the bus are not considered at risk as they alighted before the cases boarded.
"The two cases also took other bus trips during their infectious periods. ARPHS investigations are continuing and information about the routes, dates and times of these other trips will be shared as it becomes available.
"As a general rule, people should continue to adhere to Auckland's Covid-19 alert level 3 restrictions, and to be vigilant for the signs of Covid-19, which can include one or more of the following:
• New or worsening cough
• Runny nose
• Difficulty breathing
• Sore throat.
"Anyone who has shown these symptoms, or who develops them, should free phone Healthline for advice (0800 358 5453) and arrange to get tested."
The health service said anyone who may have travelled on the affected bus service with an AT Hop card can check their transaction history on the AT mobile app or by logging on to the AT Hop page at at.govt.nz.
"People using public transport in Auckland are encouraged to register their AT Hop cards to help with contact tracing, if needed," the service said.
"Hop cards enable contact tracers to access vital data such as where people got on and off buses and trains, and how many people were travelling together.
"Public health advice is also to wear a mask at all times when in public or sharing confined spaces with others.
"AT advises that its buses are thoroughly cleaned every evening. Around 83 per cent of public transport users travel using registered AT Hop cards."