The U.S. Department of Health and Human Services (HHS) officially announced that the booster shots for COVID-19 by Pfizer and Moderna would be available to all adult Americans by September 20. 

Those who have completed their first round of immunization from the two shots vaccines by Pfizer and Moderna are recommended to seek their third shot at least 8 months after their last inoculation, the HHS said in a statement.

The department also confirmed “evidence” that the vaccines show signs of fading protection over time, including the ability to fend off severe illnesses, hospitalization, and deaths. 

“Based on our latest assessment, the current protection against severe disease, hospitalization, and death could diminish in the months ahead, especially among those who are at higher risk or were vaccinated during the earlier phases of the vaccination rollout,” it reads. 

The statement said the effects would dwindle in six months or more, especially in older people with underlying health problems.

The HHS also suggested a high potential to offer booster shots to the one-dose vaccine developed by Johnson & Johnson. But the department said it still needed further data about this vaccine, given that it had not been rolled out in the U.S. until March. 

The Johnson & Johnson vaccines were temporarily postponed from the U.S. market for a short period due to reports of dangerous blood clots reactions. The pause was lifted on April 23, according to the BBC.

According to a joint statement from top US health officials, the booster doses will initially be given to healthcare workers, nursing home residents, and the elderly, who were among the first to get vaccinated in late 2020 and early 2021.

The U.S. had already approved a third dose of the Pfizer/BioNTech and Moderna vaccines for persons with compromised immune systems.

The World Health Organization (WHO) has called for richer nations to hold back on their decisions with the booster dose, considering the poorer countries (which include a wider population) were still struggling to have vaccine access.

But in the statement, U.S. officials said the imperative of the fastly evolving SARS-CoV-2 (coronavirus) demanded the presence of the third dose. 

“Our top priority remains staying ahead of the virus and protecting the American people from COVID-19 with safe, effective, and long-lasting vaccines especially in the context of a constantly changing virus and epidemiologic landscape,” they said. “We will continue to follow the science on a daily basis, and we are prepared to modify this plan should new data emerge that requires it.”

The announcement was joined by White House top medical advisor Anthony Fauci, along with leaders of the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), and the National Institutes of Health (NIH).

Like Israel, France, and Germany, several other countries have recently agreed to administer booster doses to elderly persons and people with compromised immune systems, per Reuters.