Why does the news item say Omicron is "pulling the fire alarm"?

Vaccine makers are racing to make changes to their COVID-19 shots. They hope to make sure their vaccines are effective against the newest coronavirus threat. Even before it is clear, a change is needed. Experts doubt that current COVID-19 vaccines will become useless, but they say it is crucial to see how fast companies can produce a new vaccine and prove it works. The newest version of the virus, Omicron appeared just a few weeks ago, but scientists know, it will not be the last. Omicron is pulling the fire alarm.