COVID-19 infection in children and young adults higher than reported cases, B.C. study suggests

Preliminary findings from a B.C. study which set out to get a clearer picture of the number of COVID-19 infections in children and young adults has found rates around two to three times higher than the officially reported cases.

The SPRING study is being conducted by researchers at the Vaccine Evaluation Center at BC Children’s Hospital, and first began recruiting participants aged 24 and younger late last year. Center director Dr. Manish Sadarangani told CTV News Vancouver on Thursday they ended up with just over 2,500 participants.

“What we found was in those people who are under 20, around four per cent, so around one in 25 people, had evidence of antibodies in their blood, so had evidence of a previous COVID-19 infection,” he said, and added the results were pretty similar across the younger age groups: under five, five to nine, 10 to 14, and 15 to 19.

“The 20 to 24 year olds, it was a little bit higher, sort of six to seven per cent.”

Dr. Sadarangani said their data showed an infection rate among those younger age groups that was higher than the number of cases reported from COVID-19 testing.

“If we look at the data available through the Ministry of Health and through (BC Centre for Disease Control) based on the testing that gets done when people are sick with COVID-19, so that’s around two to three times higher than those numbers,” he said. “We were expecting it to be higher. We know that not everyone gets tested. We know that some people don’t have any symptoms and wouldn’t get tested.”

Those who volunteered for the study were sent a home test kit to collect a finger or heel prick blood sample, depending on the age of the participant. The blood is blotted onto a card and then sent in for analysis. All the samples for the first phase were collected before those age groups became eligible for vaccination.

Dr. Sadarangani said it may be that some of the cases not detected by routine testing could have had lower amounts of virus, leading to an asymptomatic infection, or very mild symptoms.

“It’s still unclear what role these people play in sort of transmission in general,” he said. “We’re currently working with some of the modellers here in B.C. to combine these data with the other data that’s available to try to get a better understanding of how that fits into the models.”

He added they also don’t know what the risk of re-infection may be for those mild or asymptomatic cases.

“We’ve been sharing our data both within B.C., but also nationally with various policy makers and various organizations that make recommendations, so they can combine that with other information that’s available to them,” he said. “I think it’s just an additional piece of information, it’s an additional piece of the puzzle.”

Researchers are now conducting a deeper analysis of the preliminary findings from the first phase of the study. Dr. Sadarangani said the results are expected in the next couple of weeks, and will be shared with public health agencies.

“We can try to identify where the higher risk populations may be,” he said. “We would expect that it will probably be similar to what we already know from the testing data, but you never know what you’re going to find, so I think we have to do the analysis and see what we get.”

The study is now recruiting again for its second phase. Dr. Sadarangani said they are hoping for another 2,500 participants.

‘We’ve got about 1,500, so we’re still looking for around another 1,000 people, and we ideally really want to get these in as soon as possible, but definitely before the vaccine program extends to this paediatric age group,” he said. “What our test can’t easily do is distinguish people who have antibodies from vaccination and people who have antibodies from infection.”

Dr. Sadarangani said they are also eventually planning to study the immune response from the COVID-19 vaccine in 12 to 24 year olds.

“We had all of the infrastructure and everything in place to be able to look at that,” he said. “We decided to take advantage of the setup that we had to look at those vaccine responses.”

Anyone who wants to learn more about participating in the SPRING study can find details online