HIQA: No clear evidence that long-term coronavirus immunity is possible

13 May 2020

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A HIQA report on all the available Covid-19 research has said there is little proof so far that there could be long-term immunity to the coronavirus.

The Health Information and Quality Authority (HIQA) has collated academic research on what we know so far about a number of topics related to the novel coronavirus, SARS-CoV-2. Its four summaries, published today (13 May), include what we know about potential immunity to the virus and if children can spread it.

HIQA’s deputy CEO and director of health technology assessment, Dr Máirín Ryan, said on the issue of long-term immunity that some studies have shown that antibodies against SARS-CoV-2 develop soon after infection.

This includes immunoglobulin G antibodies, which contribute to long-term immunity and have been detected for at least two months after infection. However, Ryan said that as this latest coronavirus is new, there is no clear evidence yet to suggest there is long-term immunity.

“Continued monitoring is needed to assess the adequacy and duration of the immune response for Covid-19. Evidence for other types of serious coronavirus infections, such as SARS-CoV-1, shows that the antibody response is maintained for one to two years after initial infection and decreases thereafter,” she said.

“As yet, it is also not certain if antibodies are transferred from mother to the child in the womb via the placenta.”

In the evidence summary on immunity, HIQA pointed to the fact that many of the studies in this area have not yet been peer reviewed and the overall quality of evidence was low.

Ryan also said that we can’t yet determine if reinfection is possible after recovery from Covid-19.

“While some individuals have tested positive after recovery, this is likely due to virus re-detection where there is intermittent shedding of the virus rather than reinfection with a second virus,” she said. “To date, there is no evidence that these individuals are infectious to others.”

Children not shown to significantly spread Covid-19

HIQA also said that the limited evidence collected so far appears to suggest that children are not substantially contributing to the spread of Covid-19 in households or schools.

While one study showed high transmission of Covid-19 among adults aged 25 and older, transmission was low in younger people, especially aged under 14.

“An Australian study that examined potential spread from 18 confirmed (nine students and nine staff) cases to over 800 close contacts in 15 different schools found that no teacher or staff member contracted Covid-19 from any of the initial school cases,” Ryan said.

“One child from a primary school and one child from a high school may have contracted Covid-19 from the initial cases at their schools.”

Colm Gorey was a senior journalist with Silicon Republic