In May 2021, as more than a million Americans a day continued to receive vaccinations aimed at saving lives and stemming the COVID-19 pandemic, people began reporting that they had received unsolicited phone calls from a source identifying itself as the Centers for Disease Control (CDC) and asking for personal information for a "national immunization survey."
In social media conversations, some expressed skepticism about the origin and purpose of the calls. Some even claimed they blocked the caller's phone number. Snopes readers have inquired about the legitimacy of these phone calls.
According to the CDC's website, the National Immunization Survey is real, and phone calls on behalf of that survey originating from the following Chicago numbers are legit:
Have you been called by 312-871-4241, 312-871-4242, or 312-871-4243 (Caller ID CDC NATL IMMUN) about the National Immunization Surveys (NIS), including the NIS-Child, NIS-Teen, NIS-Child Influenza Module (NIS-CIM), or NIS-Adult COVID Module (NIS-ACM)?
Please be assured that you were contacted about a survey sponsored by the Centers for Disease Control and Prevention (CDC). The NIS-Child, NIS-Teen, NIS-CIM, and NIS-ACM are conducted for CDC by NORC at the University of Chicago.
You or a member of your household may have a chance to take part in an important national survey that provides information to help guide your state and your country’s health policies.
Participation in these surveys, which have been conducted since 2005 by the nonpartisan and objective research organization NORC at the University of Chicago, is entirely voluntary and participants' names and private information are kept confidential in accordance with federal law, the CDC says. Prospective participants are chosen at random.
Although current participants are likely to be asked if they've received a COVID-19 vaccination in particular, the surveys were designed to track participation in a range of inoculation programs (a module with COVID-19 questions wasn't added until April 2021).
People with questions or concerns about the National Immunization Survey can contact the survey administrators as NORC directly, the CDC says:
The surveys are conducted on behalf of the Centers for Disease Control and Prevention (CDC), and are authorized by the Public Health Service Act [Section 306]. The phone surveys provide important information about childhood vaccinations and related health issues. If you received a call or a letter and have any questions about these surveys, please call the survey contractor, NORC, toll-free at 1-877-220-4805. Someone is usually available to answer the phone from 9AM to 9PM in your time zone. If possible, please call from the same phone line that received the call from 312-871-4241, 312-871-4242, or 312-871-4243. This helps us more quickly direct your call to someone who can answer your questions. If you leave a message, we try to return all calls received between 9AM and 9PM within one to two hours.
If you prefer to use a TTY, please call the AT&T Relay Service at 1-800-855-2880 and request that NORC be called at 1-877-220-4805
If you have doubts about the legitimacy of a phone call you have received claiming to be on behalf of the CDC, you can call the survey contractor toll free at 1-877-220-4805 to verify.