A trio of women were on Friday arrested on suspicion of helping 500 people buy bogus coronavirus vaccine exemption certificates alleged to have been issued by a Hong Kong doctor.

A police source said the women, between 56 and 71, were taken into custody after a police investigation suggested that the three had taken a referral fee of HK$300 (US$38) per patient after they introduced people to Dr Tai Kong-shing at his Yau Ma Tei clinic in August and September.

Tai was earlier accused of issuing vaccine exemptions without proper consultations.

The three women were picked up when detectives from the Kowloon West regional crime unit raided their homes in Tai Po, Sau Mau Ping and Lantau on Friday morning.

The source said one owned a beauty parlour, another worked as an insurance agent and the third was a housewife. Officers also seized their mobile phones as part of the operation.

The three are being held for questioning and none have been charged.

Tai was among six doctors who were arrested by police last month on suspicion of issuing bogus exemptions. Another doctor has been wanted by police since March.

Retired civil servant Kwok Cheuk-kin meets the press outside the High Court after he won a judicial challenge against the government’s invalidation of about 20,000 vaccination exemption certificates.

The government decided to invalidate more than 20,000 vaccination exemptions issued by the seven doctors, which triggered a judicial review of the legality of the move asked for by retired civil servant Kwok Cheuk-kin.

The High Court ruled on October 21 that the government had no power to cancel the exemptions.

The judge said that the health secretary could not identify the source of his authority for the cancellations and that there was no statutory mechanism to overturn a doctor’s opinion on unsuitability for vaccination.

But the government on Tuesday said that, instead of an appeal against the court ruling, it would amend the vaccine pass regulations to give the health secretary power to invalidate the documents.

The amendment came into force on Wednesday and was submitted to the Legislative Council for negative vetting, a process where the government implements a law and legislators scrutinised it later.

Secretary for Health Lo Chung-mau on Wednesday said the documents issued by the seven doctors would be invalid from November 9, and any vaccination exemptions issued by them in the future would be also be cancelled.

The government said the seven doctors affected had until November 1 to submit written representations in their defence.