During an earnings call, Moderna seemed to admit that their COVID-19 vaccine only lasts for 6 months, adding that a third “booster” shot will “likely be necessary” due to the Delta variant, which experts have compared to hay fever or the common cold.

Moderna released a statement on Thursday claiming that their COVID-19 vaccine effectiveness “does not wane in the first 6 months after the second dose,” reported the New York Times. However, Moderna appeared to change their tune during an earnings call shortly after, claiming that booster shots would be necessary this fall to curb the Delta variant, which experts have previously compared to hay fever and the common cold, as National File reported.

“We believe a dose three of a booster will likely be necessary to keep us as safe as possible through the winter season in the Northern Hemisphere,” said Moderna President Dr. Stephen Hoge during the call. The piece also pointed out the Pfizer and BioNTech report of their own mRNA vaccine durability, which showed that the estimated effectiveness of the vaccines decline more than 12% after 6 months. One notable revelation from the New York Times report was that the strength of the antibodies against variants “waned substantially by six months after the second dose,” for those who have received the Moderna coronavirus vaccine.