With a new partnership to propel the completion of U.S. vaccine supplies for adults, U.S. President Joe Biden is confident that there will be enough doses for American adults before the initial timeline of July.

Potential Pitfall Looms

Biden said on Tuesday that there will be enough COVID-19 vaccines for all American adults by May, a projection that is two months earlier than initially expected.

However, completing the vaccine doses does not mean all adults in the United States will be vaccinated by the end of May, Biden said. It also does not mean that the new timeline will ensure adult herd immunity. Administration of all the vaccines can last for months, experts said.

Aside from vaccine administration potentially taking longer, distribution delays could also push back the country's goals for herd immunity through vaccination.

On the other hand, a White House official said that the government is "in close coordination with states across the country" as it urges state leaders to act fast in implementing timeline goals.

How Biden Plans to Achieve End-of-May Goal

Biden also announced on Tuesday that the government made a deal with Johnson & Johnson for a COVID-19 vaccine that Merck & Co. will help to produce.

The main goal is to produce more vaccines at a faster rate as new coronavirus variants continue to be detected in the U.S. and other countries.

Johnson & Johnson's vaccine was granted emergency authorization by the Food and Drug Administration (FDA) over the weekend, and while the Merck partnership could help produce more doses, experts raised concerns about how fast the latter will adapt.

Merck & Co. attempted to develop its own COVID-19 vaccine but was unsuccessful. Under the deal with Johnson & Johnson, the pharmaceutical company has to convert facilities into manufacturing and packaging locations in line with that of Johnson & Johnson.

Johnson & Johnson also has its own problems that could pose delays for Biden's end-of-May timeline. The company has experienced manufacturing delays at its Baltimore plant.

Some States Defy Health Advice

As hopes climb for the new vaccine timeline, some states have chosen to defy the advice of health officials while the government continues work on getting Americans vaccinated.

Hours after Biden announced the new timeline, Texas Gov. Greg Abbott said he is planning to issue an executive order that should take effect on March 10. The order will "open Texas 100%," he said.

Mississippi Gov. Tate Reeves followed suit, stating that starting Wednesday, all mask mandates in state counties will be lifted. He added that all businesses will be allowed to operate at 100 percent capacity.

Centers for Disease Control and Prevention (CDC) Director Dr. Rochelle Walensky earlier warned that states should not lift restrictions while the vaccination program is underway as it could push a reversal in declining COVID-19 cases.