There are no published, scientifically supported thresholds for serious impacts on public health or healthcare capacity, AND SERIOUS health consequences at which point mandatory inoculations that only deliver one of 29 antibody types must be used regardless of personal objection.  Additional rationale follows.

Per CDC current statistics for Region3 (includes VA) 99.265% of children under 18 have not presented with the virus.  https://covid.cdc.gov/covid-data-tracker/#demographicsovertime

If staff is terrified of 0.735% infected students, they should take appropriate self-distancing and advanced masking personally.

Estimates are that up to 30% of the US population has already recovered from the virus and have superior antibodies, all 29 types, not just the Spike Protein antibody.  I trust a large % of Education staff has voluntarily inoculated themselves. 

Regardless, this virus remains mostly benign for most healthy people, the majority reporting no symptoms, a significant portion mild symptoms.  it is rare for otherwise healthy individuals to get serious symptoms or require hospitalizations. The well known at-risk population is the group that needs to self-protect and identify as such so additional measures can be afforded in the workplace and from colleagues.

Healthcare providers are not under stress from virus admissions.  While the presentation of children has recently spiked significantly, it is a spike from near zero, nowhere near statistical significance.

Child deaths are similarly "in the noise" per current and prior CDC data, currently ZERO per 100K.  (see link above, click all ages, cases or deaths, shorten time scale to past 6 months)

Solid world wide evidence in India, Central Africa, Mexico and other countries confirms the high effectiveness of therapeutics that include a combination of approved, off-label use under physician care of Ivermectin, Hydroxychloroquine, Azithromycine, Budesonide, and others.  Monoclonal Antibody treatments while expensive are also effective in early treatment and prevention of serious consequences.

There is simply NO Credible justification to impose inoculation of a substance that currently has such a HUGE amount of VAERS incidence reports, many orders of magnitude higher than any other prior inoculation.

Personal choice, based on true and full informed consent is mandatory and must be presented first, along with science data that stands up to expert public scrutiny, not just by those who are proponents of inculations.