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Shares of messenger RNA-based vaccine makers fell on Wednesday, as Centers for Disease Control and Prevention officials told an advisory committee that there is a “likely association” between mRNA-based vaccines for Covid-19 and heart inflammation in adolescents and young adults.
The agency also discussed the evidence for Covid-19 vaccine boosters, but suggested that data did not yet support a recommendation.
The CDC officials said that the benefits of Covid-19 vaccination “clearly outweigh” the risks posed by the vaccines. The stocks were rising in premarket trading on Thursday, after the CDC reiterated that heart inflammation was an “extremely rare side effect.”
“Only an exceedingly small number of people will experience it after vaccination,” the CDC, along with the U.S. Department of Health and Human Services and a number of professional organizations of medical workers, said in a joint statement late Wednesday. “Importantly, for the young people who do, most cases are mild, and individuals recover often on their own or with minimal treatment.”
The CDC said that it had identified 323 individuals under the age of 30 who developed either myocarditis or pericarditis, two forms of heart inflammation, after receiving mRNA-based Covid-19 vaccines. Of those, nine remain hospitalized; the rest were hospitalized and discharged or were never hospitalized.
A more serious commercial issue for the mRNA-based vaccine makers came in the agency’s discussion of booster doses, in which the CDC made clear that it was not yet convinced that boosters would be required.
In its presentation to its advisory committee, a key group called the Advisory Committee on Immunization Practices, which sets recommended vaccination schedules in the U.S., a CDC work group told the committee that, as yet, there is “no data to support recommendations for booster,” but that the agency would continue to monitor the evidence.
The work group said a recommendation for booster doses should only be made after there is evidence of actual declines in vaccine effectiveness, not just declining antibody responses seen in lab tests. The group said the emergence of a variant of the virus that the vaccines cannot protect against would also make a recommendation for a booster dose appropriate.
The working group also suggested that booster doses may only be needed in certain populations, such as residents of long-term care facilities and older adults.
Investors are counting on a substantial booster market for Covid-19 vaccines. Analysts expect
(ticker: MRNA) to sell $12 billion worth of its Covid-19 vaccine next year, $5.3 billion in 2023, and $4 billion in 2024, according to FactSet. For
(BNTX), revenue estimates for its Covid-19 vaccine next year are $6.5 billion, and $4.3 billion in 2023, according to FactSet.
“Boosters will remain [an] outstanding question,” Jefferies analyst Michael Yee in a Wednesday note. “ACIP is working through the necessary requirements to justify subsequent booster doses, given infections are decreasing and long-term efficacy and safety has not been followed long enough to justify it yet.”
Shares of
closed down 1.4% on Wednesday, while shares of Moderna fell 4.2%, and shares of BioNTech fell 3%. Shares of
(CVAC), another mRNA firm making a Covid-19 vaccine, slipped 2%. All four stocks were in positive territory in Thursday premarket trading, with
leading with a 2.4% gain.
Key booster trials are ongoing. The CDC wrote that more data from Pfizer and Moderna will come between July and September, as will other study readouts.
“CDC is waiting for additional data before making a recommendation on COVID-19 booster shots,” wrote RBC analyst Daniel Busby in a note out late Wednesday. “Likewise, consensus among ACIP committee members was that additional data around vaccine effectiveness, booster safety, and other factors is needed before making a determination.”
The agency also said it would continue to monitor the reports of heart inflammation. In a statement, Pfizer said it was aware of the reports. “According to the CDC, this is an extremely rare side effect, and only an exceedingly small number of people will experience it after vaccination,” the company said. “With hundreds of millions of doses of the Pfizer-BioNTech COVID-19 vaccine administered globally, the benefit risk profile of our vaccine remains positive.”
Moderna, in a separate statement, said it was aware of the reports as well. “The company followed the discussion of this topic at today’s meeting of the U.S. CDC’s ACIP and will work closely with FDA and with other regulatory authorities on any appropriate next steps,” the company said.
The CDC said the rate of cases of myocarditis and pericarditis in people aged 12 to 39 after two doses of mRNA-based Covid-19 vaccines was 12.6 cases per million. The rates were higher in males than in females. It said that available data indicated that patients generally recover from symptoms and “do well.”
The ACIP meeting will continue on Thursday and Friday, though the committee is scheduled to discuss vaccines for other diseases.
Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com
