And this was with school closures and remote learning
By March 2021, a third of secondary school students and staff had evidence of prior infection based on N-antibody seropositivity, and an additional third of staff had evidence of vaccine-induced immunity based on S-antibody seropositivity.
Source: Emergence of SARS-CoV-2 Alpha (B.1.1.7) variant, infection rates, antibody seroconversion and seroprevalence rates in secondary school students and staff: Active prospective surveillance, December 2020 to March 2021, England – Journal of Infection
The take away message is that public health mitigations did little – when 1/3d got sick anyway by almost six months ago.
The only end point to a pandemic is widespread immunity via vaccination or by having acquired the disease, or both. However, per the CDC, none of the kids who had Covid is considered to have immunity- unlike Europe which treats prior infection as equivalent to being vaccinated.