Evidence indicates that by June 1, 2021, COVID-19 vaccines were broadly available in the U.S., but public‑health authorities still judged that emergency powers and some mask requirements remained justified, and subsequent events (e.g., the Delta wave) confirmed that such measures were in fact needed.

Vaccine availability by June 1, 2021

• All U.S. adults 16+ were eligible for vaccination by April 19, 2021; all 50 states, DC, and Puerto Rico had opened eligibility by that date. (cdc.gov)
• By June 1, 2021, about 50–51% of the total U.S. population had received at least one dose and about 40–41% were fully vaccinated. (usafacts.org) Among adults 18+, roughly 57% had at least one dose by May 22, 2021. (cdc.gov) Supply was no longer the binding constraint; experts were already warning that supply would outstrip demand by May. (mckinsey.com)
• So the narrow claim that vaccines would be “available” by around June 1 was broadly accurate.

But emergency powers and mask justifications did not disappear by June 1

• The federal COVID‑19 public‑health emergency, first declared in January 2020, was renewed on April 15, 2021 and repeatedly thereafter; HHS explicitly stated that a nationwide public‑health emergency still existed due to the ongoing consequences of COVID‑19. (aota.org) That is directly contrary to the idea that there was “no more justification” for emergency powers by June 1, 2021.
• CDC’s May 13, 2021 guidance allowed fully vaccinated people to forgo masks in many settings, but still required or recommended masks in specific contexts (e.g., public transportation, crowded indoor spaces) and continued to advise masking for the unvaccinated. (dw.com) Thus, the leading federal public‑health authority did not consider masks categorically unnecessary after June 1.
• Many state and local mandates and emergency orders remained in force past June 1. For example, Pennsylvania’s statewide mask mandate was not lifted until June 28, 2021, and even then masks were still required on planes, trains, buses, and other public transportation. (en.wikipedia.org) Several states (e.g., Hawaii and others listed in state‑by‑state mask‑policy summaries) maintained some form of mask requirements or emergency orders well beyond that date. (en.wikipedia.org)

Subsequent developments showed non‑pharmaceutical measures were still needed

• In June 2021, the more transmissible Delta variant was rapidly spreading in the U.S. and internationally; CDC and other experts warned that multicomponent prevention strategies, including indoor masking irrespective of vaccination status in high‑incidence areas, might be needed alongside vaccination. (cdc.gov)
• Delta became the predominant U.S. variant in late June 2021 and drove a major surge in cases during July–September 2021. (cdc.gov) CDC data show the 7‑day average of U.S. cases bottomed around 11–12k in mid‑June, then climbed to over 130k by early September 2021. (archive.cdc.gov) During this wave, many jurisdictions re‑imposed or tightened mask guidance and other public‑health measures, confirming that such tools were still needed even with substantial vaccine availability.

Assessment

• Sacks’ prediction tied vaccine availability to the end of any public‑health justification for emergency powers and masks: he argued that “on June 1st, there is no more justification for government having these extraordinary powers” and that “we even need to wear a mask beyond June 1st” would no longer be true.
• While vaccine supply was indeed ample by around that date, the continued federal public‑health emergency, ongoing CDC mask recommendations (especially for unvaccinated people and in specific settings), persistent state‑level mandates, and the rapid emergence of the Delta‑driven surge all show that significant public‑health justification for such powers and measures remained.

Because the central, time‑bound claim—that after June 1, 2021 there would be no public‑health justification for emergency powers or masks—was contradicted by policy, expert guidance, and eventual outcomes, the prediction is best categorized as wrong.