Virus antibodies after SARS-CoV-2 infection.

We would like to share our thoughts on the paper published recently in Acta Paediatrica that stated that severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) antibodies started to decline just four months after children became infected with the virus. Breuer et al. also concluded that reopening schools did not affect infection rates. The authors used the Abbott Architect SARS‐CoV‐2 IgG assay (manufacturer, region, country). The diagnostic properties of the test vary and depend on the time after exposure to the antigen. That is why different detection rates after vaccination may or may not be related to the diagnostic properties of the diagnostic test at different times. Indeed, long‐term antibody levels after vaccination are an important issue, and recent studies have found different levels of antibodies in previously uninfected adult individuals. Nevertheless, Breuer et al. did not explore antibody levels in vaccinated children, as at the time of their study only adults were being vaccinated.

In addition, different types of antibody tests give different detection rates and different seropositivity and this means that disagreements among tests are possible. , In the present study, Breuer et al. utilised a dual‐assay model to minimise the variance in sensitivity. The observed seropositivity rate from a single diagnostic test may not reflect the real epidemiological situation. This means that authors need to be careful about the implications of using this test on conclusions about school opening policies. However, this point was mentioned in the discussion of Breuer et al. In addition, the findings on school opening policies were not solely based on seropositivity found on a specific test, but rather on the trend over time, which did not change even when schools were reopened or among students who attended school during lockdown.

CONFLICT OF INTEREST

None.