Children are "not substantially contributing to the spread of COVID-19", the Health Information and Quality Authority (HIQA) has said.

It has just published four summaries of research and evidence to support the National Public Health Emergency Team's (NPHET) response to the virus. These summaries investigate the international evidence on immunity and the spread of the virus by children.

"While the evidence is limited, it appears that children are not substantially contributing to the spread of COVID-19 in their household or in schools. One study suggests that while there is high transmission of COVID-19 among adults aged 25 years or older, transmission is lower in younger people particularly in those under 14 years of age," explained HIQA's Deputy CEO, Dr Máirín Ryan.

She pointed to an Australian study that examined the potential spread from 18 confirmed cases - nine students and nine staff - to 863 close contacts in 15 different schools. All of those with COVID-19 had the opportunity to transmit it to others in their schools, however the study found that "no teacher or staff member contracted COVID-19 from any of the initial school cases".

"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," Dr Ryan noted.

Altogether, HIQA identified seven studies for this summary - five looked at intra-familial and close contact transmission, one looked at transmission in schools and one was a mathematical modeling study, which looked at the age-specific transmissibility of the virus.

"From the small number of published studies identified, it appears that children are not, to date, substantially contributing to the household transmission of SARS-CoV-2 (the virus that causes COVID-19). From one study, SARS-CoV-2 transmission in children in schools is also very low," the summary concluded.

This would appear to be reflected in Ireland's COVID-19 figures. According to the latest figures available from the Health Protection Surveillance Centre, of the 23,089 confirmed cases of the virus reported to it as of midnight on May 10, just 381, or 1.6%, were among children under the age of 14. 

Meanwhile, HIQA also found that it is still unclear whether long-term immunity is possible form SARS-CoV-2.

"Studies have shown that antibodies against SARS-CoV-2 develop soon after infection. Immunoglobulin G antibodies (that contribute to long-term immunity) have been detected for at least two months after infection.

"However, as SARS-CoV-2 is a new virus, there is no long-term evidence of immunity. Continued monitoring is needed to assess the adequacy and duration of the immune response for COVID-19," Dr Ryan said.

She noted that the 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".

And as yet, it is unclear whether antibodies are transferred from a mother to her child in the womb via the placenta.

"It is not yet possible to determine if reinfection is possible following 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. To date, there is no evidence that these individuals are infectious to others," Dr Ryan said.

The evidence summaries were developed by HIQA following requests from the NPHET's Clinical Expert Advisory Group and they are informing the national response to the pandemic.

"HIQA develops evidence summaries following a thorough search of bibliographic databases, screening of identified studies to match relevant clinical questions, data extraction and quality appraisal of included studies. This robust process ensures that public health decisions are informed by the best available evidence and information from across the world," Dr Ryan added.

The HIQA summaries can be viewed here.