The human trials of the Oxford-AstraZeneca vaccine candidate resumed in the United Kingdom on Saturday but the process is likely to take more time in India after the country’s drugs regulator asked Serum Institute of India – the pharma firm that has partnered with the UK-based company – to suspend recruitment and seek permissions afresh.

The experimental AZD1222 is regarded as the front runner for a Covid-19 vaccine and is the only candidate in phase 2/3 trials among Indians. Earlier this week, trials of the vaccine were suspended after a volunteer in United Kingdom developed serious symptoms.

“Clinical trials for the AstraZeneca Oxford coronavirus vaccine, AZD1222, have resumed in the UK following confirmation by the Medicines Health Regulatory Authority (MHRA) that it was safe to do so,” AstraZeneca said in a statement on Saturday.

Hours earlier, India’s Drugs Controller General of India (DCGI) in a letter said that SII will need to present separate clearances from the data safety monitoring board (DSMB) of the UK and India before it can approach for permission to resume recruitment of volunteers for the trial.

DCGI has also directed the Pune-based vaccine producer to closely follow up on all the individuals who have been administered vaccine doses as part of the trial so far and submit a report immediately.

On Wednesday, a day after AstraZeneca announced the global suspension, SII said it was continuing with the trials. It was issued a show-cause notice by DCGI shortly after, following which the Pune-based company – which is the largest vaccine-maker in the world – said it would halt the trials in India too.

“…After careful examination of your reply and the recommendations of the DSMB in India, in exercise of the powers vested under Rule 30 of the New Drugs and Clinical Trials Rules, 2019, direct you to… suspend any new recruitment in the phase II/III clinical trials… till further orders. Increase the safety monitoring of the subjects already vaccinated with the vaccine under trial and submit the plan and report,” said the letter sent by Dr VG Somani, DCGI.

“Submit clearance from DSMB UK, and DSMB India to obtain clearance from this office prior to resumption of future recruitment in the trial…,” the drugs controller’s letter added.

While no safety concerns were noted from the India study (part 1- phase 2 study) by the DSMB, India with first dose and from the 7 days post-vaccination safety data, it recommended pausing further enrolment until ongoing investigations of severe adverse reaction reported in the UK study is completed and the sponsor and UK DSMB are satisfied that it does not pose any safety concerns.

According to an official in the drugs controller’s office who asked not to be named, the department studied the side effects documented in the patient, and the recommendations of the DSMB India, before reaching the conclusion that further investigation was required.

“Transverse myelitis (inflammation of both sides of a section of the spinal cord) is a serious neurological disorder. Investigations are on to know the cause behind the participant developing it, and whether it was reversible or not. The department is closely monitoring their investigation in the matter, and until it is fully satisfied regarding the safety concerns there is no question of re-starting the trials. It is a matter of safety of Indians and it cannot be taken lightly,” said this person.

“The company has been asked to closely monitor all those people who have been given the vaccine dose for any adverse reaction. All participants will have to be contacted personally and a plan regarding how they [SII] are going to go about it and the report on it will have to be immediately submitted to the DCGI.”

The official also said that it is important to have adequate safeguards and monitoring because this will set a precedent for other human trials related to Covid-19 vaccine candidates in the country. “These are all new vaccine candidates that are being experimented with and that is why safety and safeguard has to be much stronger. Everyone is waiting for this vaccine and we cannot afford to be lax.”

SII representatives declined to comment.