U.S. health officials say 4.4 million Americans have rolled up their sleeves for the updated COVID-19 booster shot. The Centers for Disease Control and Prevention posted the count Thursday as public health experts bemoaned President Joe Biden s recent remark that the pandemic is over.

The White House said more than 5 million people received the new boosters by its own estimate that accounts for reporting lags in states.

Health experts said it is too early to predict whether demand would match up with the 171 million doses of the new boosters the U.S. ordered for the fall.

No one would go looking at our flu shot uptake at this point and be like, Oh, what a disaster, said Dr. David Dowdy, an infectious disease epidemiologist at Johns Hopkins Bloomberg School of Public Health. If we start to see a large uptick in cases, I think were going to see a lot of people getting the (new COVID) vaccine.

A temporary shortage of Moderna vaccine caused some pharmacies to cancel appointments while encouraging people to reschedule for a Pfizer vaccine. The issue was expected to resolve as government regulators wrapped up an inspection and cleared batches of vaccine doses for distribution.

I do expect this to pick up in the weeks ahead, said White House COVID-19 coordinator Dr. Ashish Jha. Weve been thinking and talking about this as an annual vaccine like the flu vaccine. Flu vaccine season picks up in late September and early October. Were just getting our education campaign going. So we expect to see, despite the fact that this was a strong start, we actually expect this to ramp up stronger.

Some Americans who plan to get the shot, designed to target the most common omicron strains, said they are waiting because they either had COVID-19 recently or another booster. They are following public health advice to wait several months to get the full benefit of their existing virus-fighting antibodies.

Others are scheduling shots closer to holiday gatherings and winter months when respiratory viruses spread more easily.