Can You Catch Coronavirus Twice?

Scientists in Hong Kong have confirmed the first case of reinfection – but what does this mean for vaccination research?

Researchers from the University of Hong Kong have confirmed the first case of a man being infected with coronavirus twice. The patient recovered from the virus after being infected in Hong Kong, then travelled to Europe four months later and became infected again, with a different strain of the virus.

This raises the question of whether the body can develop immunity to coronavirus COVID-19 after infection, and hence whether vaccinations which rely on the body’s immune response could be effective against the virus.

In both cases of infection the man was tested at airports and found to be positive for COVID-19. DNA sequencing of the viral strains showed that they were different strains, leading the Chinese researchers to conclude that long-term immunity cannot be guaranteed, and raising doubts about the effectiveness of vaccinations.

Protective immunity

They emphasised the importance of maintaining social distancing, washing hands and wearing face masks even after recovering from the infection a first time..

British researchers also said it cast doubt on whether a vaccine could deliver protective immunity.

Dr David Strain, Clinical Senior Lecturer at the University of Exeter and chair of the British Medical Association’s Medical Academic Staff Committee, said: “This is a worrying finding for several reasons.

“It suggests that previous infection is not protective and it raises the possibility that vaccinations may not provide the hope that we have been waiting for.”

He added: “If antibodies don’t provide lasting protection, we will need to revert to a strategy of viral near-elimination in order to return to a more normal life.”

It has not been clear whether developing an immune response to coronavirus infection confers any degree of immunity – the common cold, which is also a form of coronavirus, mutates constantly, so becoming infected with it once does not confer any immunity in the future. But until now researchers have been unable to establish whether cases of second infection of coronavirus have been of different strains, or whether the patients had simply been carrying the same virus around with them.

Taken in context

However, some experts tried to allay fears that vaccination may not be effective by pointing out that the Hong Kong patient seemed to have an unusually low immune system reaction, and that cases of re-infection were always to be expected considering the worldwide nature of the pandemic.

Brendan Wren, Professor of Microbial Pathogenesis at the London School of Hygiene & Tropical Medicine, said: “With over three million cases of Covid-19 worldwide, the first reported case of a potential re-infection with coronavirus needs to be taken into context.

“It appears that the young and healthy adult has been re-infected with a slight SARS-CoV-2 variant from the initial infection.

“It is to be expected that the virus will naturally mutate over time. This is a very rare example of re-infection and it should not negate the global drive to develop Covid-19 vaccines.”

And Dr Simon Clarke, Associate Professor in Cellular Microbiology at the University of Reading, added: “The significant thing here is that being re-infected with a mutated strain demonstrates that it is more likely to be re-infection, rather than the same infection that has hung around because the virus has not actually been got rid of, as some people have suggested happens.

“The finding of a mutant strain is absolutely nothing to be shocked or surprised by. It would actually be more interesting if there were no mutations cropping up.”

The Hong Kong study paper has been accepted by the journal Clinical Infectious Diseases.

Convalescent plasma

Meanwhile, in America, reeling from the world’s highest death rate and an economic downturn, President Donald Trump has announced that the Food and Drug Administration has issued an emergency use authorisation for ‘convalescent plasma’ to treat Covid-19, saying the “known and potential benefits of the product outweigh the known and potential risks of the product.”

The FDA said more than 70,000 patients had been treated with convalescent plasma,which is made using the blood of people who have recovered from coronavirus infections.

“Today I am pleased to make a truly historic announcement in our battle against the China virus that will save countless lives,” President Trump said at a White House briefing, referring to the coronavirus that causes Covid-19.

The announcement follows and FDA trial of scientists using convalescent plasma with patients to study its impact. It has already been used to treat more than 60,000 Covid-19 patients.

Clinical trials

However, like blood, convalescent plasma is in limited supply, and must come from donors, and while there are promising results from some studies, there have not yet been randomised clinical trials on convalescent plasma, and experts agree that more data is needed. With an election looming and no sign of an end to the pandemic, President Trump’s move may be more political than practical.

In the UK, NHS Blood and Transplant has banked more than 1,000 units of convalescent plasma for potential transfusion into people with COVID-19, and is carrying out a clinical trial which will continue until the end of the summer.

Professor David Roberts, NHSBT Associate Medical Director for Blood Donation, and also one of the trial’s Principal Investigators, said: “We thank everyone who is donating convalescent plasma. We know many people who can donate will have been through a difficult experience and we are grateful for their help in reaching this milestone.

“There is still much more to do. We can reassure people that donating convalescent plasma donation is safe and easy. You’ll also be taking part in groundbreaking research. If you get the call, please donate.”

NHSBT is now able to collect convalescent plasma at all 23 of its permanent donor centres.

So, while the work of researchers from the University of Hong Kong has confirmed the first case of a man being infected with coronavirus twice, it’s too early to say whether it’s likely that large numbers of people will be infected twice with different strains of the virus, or what this implies for Covid-19 vaccination research.