The United States has met President Joe Biden's goal of 70% of U.S. adults receiving at least one dose of a COVID vaccine by the Fourth of July, according to data published by the U.S. Centers for Disease Control and Prevention (CDC) on Monday, coming about a month behind from the target date.

The goal set by Biden back in May was seen as a crucial step toward the nation reaching herd immunity, which is when enough of the population have antibodies against a specific disease where the disease can no longer spread easily.

While reaching the 70% milestone is a significant achievement for the nation, the U.S. still faces the ongoing threat of the Delta variant, which CDC Director Rochelle Walensky recently said behaves "uniquely different from past strains of the virus."

The nation's milestone also comes less than a week after the federal health agency reversed its guidance on masks for the fully vaccinated, now recommending that fully vaccinated individuals who live in areas of high COVID infection rates begin to wear masks again in public indoor settings. The new guidance followed new CDC research which demonstrated that fully vaccinated people can not only be infected by the Delta variant, but are able to spread it to others.

The nation's seven-day average of daily infections surpassed the peak recorded last summer, before the nation had authorized a vaccine for emergency use, Walensky said during a White House press conference Monday, citing data published over the weekend.

Daily infections average reached 84,389 on Monday, according to CDC data, which was higher than the peak in average daily cases last summer, which was about 68,700 cases per day.

Still, vaccines made by Pfizer (PFE  )-BioNTech (BNTX  ), Moderna (MRNA  ) and Johnson & Johnson (JNJ  ) have been shown to be highly effective against multiple COVID strains, including Delta, and prevent severe disease, hospitalization and death.

Americans who have been hesitant to get the vaccine before seem to be more open to the shot as the Delta variant causes infection spikes across unvaccinated populations, with many getting their first dose in recent days. According to CDC data, an average of about 423,000 first doses where reportedly administered daily over the past seven days ending Sunday, representing a 24% increase week over week.

However, vaccination rates vary widely across the country. Twenty states have surpassed the 70% milestone of adults with one shot as of Sunday, according to CDC data, with Vermont, Hawaii, Massachusetts, and Connecticut each exceeding 80%.

Other states are well under the 70% goal, with 12 having fewer than 60% of adults with at least one shot, according to the CDC. At the bottom are Louisiana at 54%, Wyoming at 52% and Mississippi at 50%.