Russian intelligence has been planting disinformation about Pfizer’s COVID-19 vaccine in recent months, pushing misleading claims in four Kremlin-linked publications about the safety and efficacy of the company’s mRNA shot, an unidentified State Department official told The Wall Street Journal. The official said two of the outlets are fronts for the SVR, Russia’s foreign intelligence service; one is controlled by the FSB, which is a successor agency to the KGB; and one is linked to the GRU, which is Russia’s military intelligence service. None of the three vaccines being offered to Americans—developed and manufactured by Moderna, Johnson & Johnson, and Pfizer—have been linked to any serious side effects, and are all highly effective, according to the CDC.

A new report by the Alliance for Securing Democracy, an NGO under the aegis of the German Marshall Fund, explains what it believes is behind the Russian disinfo campaign. “The emphasis on denigrating Pfizer is likely due to its status as the first vaccine besides Sputnik V to see mass use, resulting in a greater potential threat to Sputnik’s market dominance,” it says. A Kremlin spokesman denied the report, blaming the U.S. for overreacting to what amounts to nothing more than a “debate” over vaccines.