Coronavirus: reinfection discovery may be blow to vaccine hopes

A case of a woman in Japan who tested positive for Coronavirus a second time may ultimately have meaningful implications but is for the moment a rare event, experts based in Ireland have said.

The woman is among the first worldwide to test positive twice for the virus, amid concerns about the spread of the infection. A case was confirmed in Belfast on Thursday evening.

Prof Samuel McConkey, deputy dean at the Royal College of Surgeons in Ireland, said he "already expected that [Covid-19] would reinfect people because that is what happens with the previous coronaviruses". The emergence of reinfection suggested some people may not develop a natural immunity.

“The worry is that Covid-19 could spread around the world in a devastating way in March, April and May, and then three months later it could spread around the world again because we are not protected by immunity after the first infection.”

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“That’s the worry, that if there’s no acquired immunity it will circulate around for years or until we find a technology to control it.”

However, another expert cautioned the reinfection was for now an uncommon occurrence. "It's a rare event. There's only been a couple of cases reported. It's probably more of scientific interest rather than something that will have a big impact in terms of how we manage the epidemic," said Patrick Mallon, professor of microbial diseases in UCD and a consultant in infectious diseases at St Vincent's University Hospital in Dublin.

Swine flu

Prof Mallon believes populations will develop some immunity, even if it re-emerges in later waves. This occurred with swine flu, which caused significant sickness and death when it first emerged. When it re-emerged, it didn’t cause as much difficulty, he said.

“The issue with this infection is it is sweeping through a population that has never seen it before … once it has completed its cycle of infections there will be an element of immune protection,” he said.

Prof McConkey said the emergence of reinfection suggests it may be difficult to manufacture an effective vaccine against coronavirus. “In general it is easier to make vaccines for these infections in which natural infection really does protect from acquiring the disease a second time.”

He added that an alternative to treating the virus may become available. “I would be a bit confident that we will have a small molecule within three to six months which will be an inhibitor of this virus,” he said.

The pharmaceutical company Gilead is working on a drug called Remdesivir, which is in human trial stage at present. "I'm hoping they work and I'm reasonably optimistic," Prof Mallon said.

“The current approach of case-finding and trying to nip these infections in the bud before they get established in communities, that needs to be the focus.”