A participant in AstraZeneca's COVID-19 vaccine trial in India claims he had an adverse reaction after receiving a shot of the coronavirus vaccine that is in late-stage testing, adding to a list of recent woes for the British drugmaker's experimental immunization.

The Indian Council of Medical Research (ICMR), India's medical research regulator, is assisting an inquiry into the participant's allegation but told Reuters on November 29 there is currently "no immediate cause of concern," nor are there any plans to halt the trial.

The 40-year-old trial participant, who received the vaccine shots on Oct. 1 at a trial site in Chennai, India, said he experienced acute "neurological and psychological" side effects after he received the vaccine. He is seeking 50 million rupees—around $676,000—in compensation. The man also called for the testing, manufacturing, and distribution of the AstraZeneca vaccine to be "stopped immediately."

The Serum Institute of India, the vaccine manufacturer running the AstraZeneca vaccine trials in India, said in a statement to India's Economic Times that there is "absolutely no correlation" between the man's condition and the vaccine trial. It called the man's allegations "malicious and misconceived" and said it would seek around $13.5 million in damages for the allegations.

The Serum Institute has already produced millions of doses of AstraZeneca's vaccine.

The ICMR, the Serum Institute, AstraZeneca, and the Oxford Vaccine Group, which developed the vaccine with AstraZeneca, didn't immediately reply to Fortune’s requests for comment.

AstraZeneca experienced a late-stage trial hiccup in September when it halted clinical trials across the globe because of a suspected adverse reaction in a U.K.-based trial participant.

The vaccine's trials in the U.K. resumed on Sept. 12, four days after the suspension, following safety reviewers' confirmation that it was safe to do so; the Serum Institute received approval to resume trials on Sept. 16; U.S. trials resumed in October.

The India trial participant's allegations follow last week's criticism of AstraZeneca for a perceived lack of transparency in its clinical trial analysis.

On Nov. 23, AstraZeneca announced that an early analysis of its late-stage clinical trial data showed its COVID-19 vaccine candidate was either 62% or 90% effective, depending on how the doses were administered to participants. AstraZeneca's announcement followed COVID-19 vaccine trial results from Pfizer and Moderna, which had both reported efficacy rates of 90% and up.

AstraZeneca's results were widely considered positive and promising, especially because its candidate is relatively cheap and easy to produce and a large portion of its doses are slated to go to low-income countries. It's also easier to transport and store than Pfizer's and Moderna's vaccines because it doesn't require ultralow storage temperatures.

But days after its Nov. 23 news, AstraZeneca and Oxford came under fire for initially omitting some information about the trial results, including that that the 90% efficacy rate was discovered by mistake, when researchers unintentionally gave a group of participants half a dose of the vaccine instead of the full dose.

AstraZeneca defended its results and methods, saying it used the "highest standards" and that it would carry out further analysis.