for most children and adults who have antibodies, the virus causes mild cold-like symptoms.
between november and january is usually the busiest time for rsv at cheo, and more than 200 young children can end up in hospital each year.
but this has not been a typical year.
in 2019-2020, cheo recorded 455 positive tests for rsv. during the fall and winter of 2020-2021, when mobility was limited and public health restrictions were in place, there were just six positive rsv tests and no hospitalizations, samson said.
canada-wide, there were only 239 positive cases of rsv between aug. 29, 2020, and may 8, 2021, compared with 18,860 during a similar period the previous year (between aug. 25, 2019, and may 2, 2020), according to the cmaj commentary.
“the virus seemed to disappear.”
samson is concerned that the resurgence this year will create a “double cohort” of vulnerable children because very few have been exposed to it since the pandemic began.
“we have two whole birth cohorts that wouldn’t have been infected.”
in a resurgence of rsv in australia, the median age of children infected was 18.4 months, compared to between 7.3 and 12.4 months in previous years.
“this could suggest that infants who were not exposed to rsv in their first year did not develop sufficient immunity, such that they remained susceptible into their second year,” the authors of the cmaj commentary wrote.