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(NEXSTAR) – With the delta variant of COVID-19 overwhelming hospitals across the country, government health officials have recommended a booster shot of Moderna or Pfizer vaccine – but what about Americans who received the Johnson and Johnson vaccine?

The good news is that Health and Human Services officials say there will likely be a J&J booster update in the near future, but it’s not yet clear when that announcement will come.

On Wednesday, the Centers for Disease Control and Prevention said that, starting Sept. 20, the Biden administration plans to offer COVID-19 booster shots for people who were given the Pfizer or Moderna vaccine at least eight months earlier.

“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,” public health and medical experts from the U.S. Department of Health and Human Services said in a statement. “For that reason, we conclude that a booster shot will be needed to maximize vaccine-induced protection and prolong its durability.”

When it comes to the single shot vaccine from Johnson & Johnson, HHS officials said they are still awaiting data because “administration of the J&J vaccine did not begin in the U.S. until March 2021.”

“For those who got the J&J vaccine: We do expect that boosters will be needed in the future and we are expecting more data in the coming weeks that will help us make recommendations for people who got J&J,” said U.S. Surgeon General Dr. Vivek Murthy in a tweet.

CDC data show that more than 14,000,000 Americans have received the J&J COVID-19 vaccine.

Murthy assured Americans that the protection from all of the vaccines against the worst COVID-19 outcomes remains high, but the new data show that protection against mild and moderate cases is decreasing over time because of normal waning immunity and the impact of the delta variant.

“We are concerned that this pattern of decline will continue and eventually lead to less protection against severe illness, hospitalization and death.” Murthy said. “Boosters may help restore that protection.

HHS officials say their top priority remains staying ahead of the “constantly changing” virus as it continues to mutate, creating a fluid situation that may require modifications to the plan.

“We also want to emphasize the ongoing urgency of vaccinating the unvaccinated in the U.S. and around the world,” the statement concludes. “Nearly all the cases of severe disease, hospitalization, and death continue to occur among those not yet vaccinated at all.”

Can I mix vaccines?

The government is encouraging people to stick with the same vaccine provider, but hasn’t mandated it.

The CDC recommends people with compromised immune systems who received either Pfizer or Moderna when they were originally vaccinated should seek an mRNA vaccine for their third dose, and should stop at three doses.

For people who received the J&J vaccine, however, the science is again unclear. “There is not enough data at this time to determine whether immunocompromised people who received the Johnson & Johnson’s Janssen COVID-19 vaccine also have an improved antibody response following an additional dose of the same vaccine,” the CDC guidance reads.

The federal stance hasn’t stopped local health officials from making their own decisions when it comes to the J&J vaccine.

San Francisco’s Public Health Director Grant Colfax said earlier this month that the city is allowing people who first received the J&J vaccine to be given a booster shot of Pfizer or Moderna as long as they consult with their doctor or health provider first.

A new study also found that mixing an mRNA COVID-19 vaccine like Pfizer with a viral vector vaccine, which is what the J&J shot is, can elicit a strong immunological response.

As J&J recipients in the U.S. wait out the lag on test data, Dr. Murthy reassured all vaccinated Americans that their current protection is strong and that “we are not recommending that everyone go out and get a booster today.”