A US molecular biologist said that there was no scientific basis for those with “natural immunity” to Covid-19 to be required to quarantine, Magistrates’ Court heard.

Sophia Cannonier and her husband, Michael Watson, are charged with breaching public safety regulations after returning from a trip overseas in July 2021 at the height of the pandemic.

The Government had earlier passed emergency powers ruling that travellers who had not been vaccinated had to spend 14 days in quarantine at one of six government-approved hotels at their own expense.

However, the couple argued that while they had not received the vaccine, they had developed natural immunity after being exposed to the virus.

As their trial continued yesterday, the court heard evidence from Christina Parks, who said that it was “universally accepted” that natural immunity was superior to vaccine-induced immunity.

Dr Parks, who received a PhD in cellular and molecular biology from the University of Michigan, accepted that some jurisdictions including Bermuda had made distinction in law between those who had natural immunity and those with vaccination immunity, but argued that such rules were not grounded in science.

“As a scientist, all I can say is some other considerations, be it money or politics, came into it because these decisions were not based on the science,” she said.

“There is no scientific basis for a rule which has a quarantine for those what are unvaccinated but have natural immunity.”

Dr Parks, who previously provided evidence for courts in both the United States and Australia, said that Covid vaccines had been tested to determine if they would lower the risk of death and hospital admission, but not to determine if they would limit spread.

She said those who were exposed to the virus naturally developed “sterilised immunity”, preventing symptoms and decreasing the likelihood of passing the virus on to others.

“They needed to be more clear with people,” she said. “People went out thinking that they had sterilised immunity when they did not.”

Based on blood tests from both of the defendants taken months before and after their July 2021 flight, Dr Parks said both Mr Watson and Ms Cannonier had natural immunity.

She said tests from January of that year showed both had “robust” antibody responses sparked by exposure to Covid-19, although Ms Cannonier’s readings were lower than her husbands.

Dr Parks said further tests on Mr Watson showed he still had strong immunity in May and August of that year, while results that December showed an increased response, which likely indicated that he had been re-exposed to the virus.

In the case of Ms Cannonier, Dr Parks said results in May and August showed “waning immunity”. However, her autoimmune response was stronger in December of that year after likely re-exposure.

She said based on the results, in July of 2021 both had Covid-19 antibodies and neither should have been considered a threat to public health.

“They should pose no threat whatsoever because they have sterilising immunity and would not be expected to spread the virus at all,” Dr Parks said.

Under cross-examination from Alan Richards, for the Crown, Dr Parks said she did not know why she had been selected to present expert evidence for the defence but that it may have been because of evidence she had given on the subject on hearings in the US.

While Mr Richards suggested that the scientific knowledge on the subject had evolved since the start of the pandemic, Dr Parks responded the change had been “marginal”.

“Our understanding of natural immunity versus vaccine-induced immunity has been built over 200 years,” she said. “This doesn’t significantly change this.”

Giving testimony during the trial last year, Ms Cannonier emphasised that blood tests showed that the family were immune from the virus.

The couple had also claimed that, after being out of work for many months as a result of the pandemic, they could not afford to quarantine at a hotel.

However, the family did quarantine in their own home after returning from overseas.

The couple have pleaded not guilty to a refusal to comply with a mandatory quarantine regulations and failure to complete a Travel Authorisation form on July 11, 2021.

They have also pleaded not guilty to leaving their home before the end of their quarantine period.

Ms Cannonier has further denied allowing unauthorised people to visit her on the same day.

The trial is scheduled to continue later this month, at which time the Crown will indicate if it will seek to bring expert evidence to rebut the evidence of Dr Parks.

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