Pfizer executives on Dec. 13 said they expect to make less money than expected in 2024, a few months after acknowledging 2023 sales would likely be lower than expected due to flagging COVID-19 vaccine and drug uptake.

Pfizer shares hit a 10-year low after the announcement.

Revenue from Pfizer's COVID-19 vaccine and Paxlovid drug, which peaked at $57 billion in 2022, are now expected to be $8 billion in 2024. That would be down from the approximately $12.5 billion Pfizer forecasts making in 2023.

"We want to be conservative," Pfizer CEO Albert Bourla said on a conference call with investors. "We want to be reliable so we won't create uncertainty, which was the case, unfortunately, this year."

Pfizer used some of its COVID windfall to acquire companies, including a $43 billion deal for cancer drugmaker Seagen it expects to close this week, and launched a new respiratory syncytial virus (RSV) vaccine based on the same modified messenger RNA technology behind its COVID vaccine. But the recent RSV launch has been disappointing, trailing a rival's shot, and shares have fallen 44 percent so far this year.

In addition, COVID vaccine update in the United States has dropped sharply with the latest round of shots, two of which, including Pfizer's, were cleared without any human data.

Just 17 percent of adults and 7.7 percent of children have received one of those shots, according to data from the U.S. Centers for Disease Control and Prevention (CDC), amid concerns about the lack of data, side effects, and the necessity of additional doses in light of the low COVID-19 activity.

"For COVID vaccines, the top concern here is worry about side effects," Dr. Mandy Cohen, the CDC's director, told a American Medical Association conference this week.

She said doctors should tell patients, "I've gotten these vaccines myself, and recommend them for you, too."

Dr. Cohen repeated the contested claim that heart inflammation, a serious side effect, is more common after COVID-19 than after COVID-19 vaccination. That claim stems from a non-peer-reviewed CDC paper. A number of other studies have found the opposite.

Pfizer also forecast 2024 adjusted profit in the range of $2.05–2.25 per share, lower than analysts' expectation of $3.16.

Pfizer shares were off another 7.3 percent on Wednesday, which would erase over $12 billion in market capitalization if losses continue through the day.

Shares of COVID vaccine rival Moderna were down nearly 5 percent, while Pfizer's German vaccine partner BioNTech were off 5.5 percent.

Moderna and Novavax, which make the other available COVID-19 vaccines in America, have not yet issued fresh outlooks on 2024.

"They're in a bad place honestly," said Jeff Jonas, portfolio manager for Gabelli Funds, which owned over 750,000 Pfizer shares as of September, according to data from the London Stock Exchange Group

Mr. Jonas said the company has taken on a lot of debt to do deals like Seagen. But he is skeptical the company has done enough to fully offset lost revenue from drugs expected to face generic competition in coming year. "They're stuck in their ways and then they're not necessarily going to make the type of bold move that they need to reinvigorate R&D," Mr. Jonas said of research and development.

Seagen is expected to add $3.1 billion to revenue next year, and Pfizer expects annual revenue in the range of $58.5 billion to $61.5 billion.

Pfizer drew in more than $100 billion in 2022, thanks to robust sales of Paxlovid and Comirnaty, its COVID-19 vaccine.

Pfizer thought it would make $21.5 billion in 2023 from Comirnaty alone, but recently scaled back that projection $11.5 billion because fewer people have been getting vaccinated than expected. It also downgraded its outlook for Paxlovid, which is endorsed by the U.S. government as a COVID-19 treatment.

Because of flagging revenue, Pfizer has previously said it would implement cost-cutting measures, and has terminated some employees while shutting down multiple facilities.

Facing Lawsuits, Concerns

Pfizer is facing multiple lawsuits and pressing questions, including a new suit from Texas that accuses the company of misrepresenting the COVID-19 vaccine's efficacy when the company announced clinical trial results in 2020.

Pfizer promoted the relative risk reduction estimate, but did not mention the lower, absolute risk reduction estimate, Texas Attorney General Ken Paxton said. That violated state and federal law, Mr. Paxton, a Republican, alleged.

Another suit from Mr. Paxton, who survived an impeachment effort, accused Pfizer of knowingly distributing adulterated drugs for children with attention-deficit/hyperactivity disorder (ADHD).

Pfizer has not responded to an inquiry about the suits, which were filed in the fourth quarter in Texas county court.

The Pfizer-BioNTech COVID-19 vaccine has also recently been discovered to include a previously unknown-to-the-public component, a Simian Virus 40 (SV40) DNA sequence, prompting renewed concerns about leaving the shot on the market.

Some scientists say the inclusion and the resulting residual DNA could be linked to cancer and other serious problems, though many say further research is needed.

The U.S. Food and Drug Administration, which cleared the COVID-19 shots, has said that "no safety concerns related to the sequence of, or amount of, residual DNA have been identified."

Reuters contributed to this report.