VANCOUVER -- More than 200 schools in Metro Vancouver and the Fraser Valley have had COVID-19 exposures over the last two weeks, according to exposure lists maintained by local health authorities.

As of Friday, there are 224 schools listed on the Fraser Health and Vancouver Coastal Health websites, excluding schools on the Sunshine Coast and other areas of VCH that are not part of Metro Vancouver.  

The number of exposures in the region has declined slightly since last week, when there were a total of 238 schools on the two lists.

Schools are added to the lists when at least one person in the school community tests positive for COVID-19 and is on school grounds during their infectious period. Letters are sent home to notify parents, teachers and staff of the exposures, and public health officials follow-up with those who were in close contact with the infected person directly.

Once 14 days have passed since the last time an infected person was present at a school, the school is removed from the online list.

Most of the schools currently on the list are in the Fraser Health region, where the majority of B.C.'s coronavirus cases have been found throughout the pandemic.

There were 175 schools in the health authority with active exposures as of Friday, down from 184 the week before.

Vancouver Coastal Health currently has 49 active school exposures, down from 54 last week.

The slight downward trend in the number of active exposures comes alongside an overall downward trend of COVID-19 cases in B.C., but the number of schools on the lists remains quite high.

Using archived versions of the Fraser Health school exposures page, CTV News Vancouver was able to determine the number of schools on the list for three Fridays earlier on in the pandemic: April 16, April 9, and March 5.

CTV News contacted the health authority to inquire about the number of exposures on the list on Fridays since April 16. After looking into it, a Fraser Health spokesperson said there is no archive and no easy way of compiling numbers from a specific day.

Still, from looking at the numbers that are available, it's clear that 175 exposures in schools is a high number relative to the totals seen over the course of the pandemic.

On April 16, when B.C.'s seven-day rolling average of new cases was more than twice as high as it is currently (1,077 then versus 449 now), there were 169 schools listed on the page.

A week earlier, on April 9, there were 136 entries on the list, which is only slightly higher than the 124 that were on the list a month earlier on March 5.

For comparison, the province's rolling seven-day average stood at 1,084 cases per day on April 9 and 522 on March 5.

B.C. health officials have said throughout the pandemic that COVID-19 infections in schools reflect transmission happening in the broader community, and that schools themselves are not drivers of coronavirus transmission. 

Teachers have largely rejected that assertion and pushed for measures - such as expanded mask mandates and online learning - to limit transmission in schools. 

This data on school exposures suggests that if exposures are correlated to daily case counts, it is as a lagging indicator, similar to hospitalizations. The number of hospitalizations tends to take longer to start rising or declining than the rolling seven-day average.