The Morbidity and Mortality Weekly Report (MMWR) is a series of epidemiological science periodicals published by the United States Centers for Disease Control and Prevention (CDC). The MMWR series comprises 4 publications: the Weekly Report (MMWR Weekly), published weekly on Thursdays, and 3 titles presenting longer-form reports published on an ad hoc basis: MMWR Recommendations and Reports, MMWR Surveillance Summaries, and MMWR Supplements. MMWR was originally established as Weekly Health Index in 1930, changing its title to Weekly Mortality Index in 1941 and Morbidity and Mortality in 1952. It acquired its current name in 1976. It is the main vehicle for publishing public health information and recommendations that have been received by the CDC from state health departments. Material published in the report is in the public domain and may be reprinted without permission. As of 2026, the journal’s acting editor-in-chief is Leonard Jack, who also serves as editor-in-chief of the CDC's peer-reviewed journal Preventing Chronic Disease.
According to Journal Citation Reports, 2025 2-year impact factors for the MMWR series (and rankings out of 443 publications in the “Public, Environment and Occupation Health’ category) were
Morbidity and Mortality Weekly Report: 16.2 (rank 7th)
Surveillance Summaries: 96.9 (rank 1st)
Recommendations and Reports: 51.3 (rank 2nd)
MMWR Supplements was not given a 2025 impact factor.
MMWR has its roots in the establishment of the Public Health Service (PHS). On January 3, 1896, the Public Health Service began publishing Public Health Reports. Morbidity and mortality statistics were published in Public Health Reports until January 20, 1950, when they were transferred to a new publication of the PHS National Office of Vital Statistics called the Weekly Morbidity Report. In 1952, NOVS changed the name of this publication to the Morbidity and Mortality Weekly Report, which continues through the current day (2026).
Several notable articles have been published in the report including:
The spread of hepatitis A among attendees of jam band concert tours (September 2003)
Several dozen deaths in teens participating in what is called the "choking game" (February 2008)
A report about the elevated death rate among fishermen in the Pacific Northwest (April 2008)
Improvements in public health after the implementation of municipal smoking bans (January 2009)
The initial reports of a novel swine flu virus which led to the 2009 flu pandemic (April 24, 2009)
On the other hand, there have been articles that have been controversial, such as a report stating a low concerns for risks of elevated blood levels of lead in Washington, DC (April 2004). The article was notable and later criticized for not emphasizing the risks, and now is available together with two amending "notices to the readers" by CDC from 2010.
Five cases of Pneumocystis carinii pneumonia (PCP) were reported in what turned out to be the first reporting of AIDS in the medical literature (June 5, 1981). Los Angeles-based general practitioner Joel Weisman and immunologist Michael S. Gottlieb of the UCLA Medical Center had encountered a series of gay male patients with symptoms that appeared to be immune system disorders including significant loss of weight and swollen lymph nodes, accompanied by fever and rashes, in addition to two patients with chronic diarrhea, depressed white blood cell counts and fungal infections. Gottlieb diagnosed these and a number of his other patients as having pneumocystis pneumonia. A report they jointly wrote and published in the June 5, 1981, issue of Morbidity and Mortality Weekly Report, described their patients as "5 young men, all active homosexuals, [who] were treated for biopsy-confirmed Pneumocystis carinii pneumonia at 3 different hospitals in Los Angeles, California" of which "[t]wo of the patients died" by the time of the original report. This notice has been recognized as the first published report marking the official start of the AIDS pandemic and as "the first report on AIDS in the medical literature".
Drinking water lead report controversy
Between 2001 and 2003, various tests showed that the lead content in drinking water in Washington DC more that 10% of the tests were higher than 15 ppb (parts per billion), which was the "action level" fixed by U.S. Environmental Protection Agency (EPA) for stagnant first draw water, and not indicative of typical usage. Some of the tests were prompted by EPA's lead and copper rule, while others were conducted by professor Marc Edwards, while trying to find the causes of an increased rate of pinhole leaks in copper water pipes. He found some rather high values in a few households, sometimes exceeding 1250 PPM. From 2002 on the matter started to be noted by news media.
Lead is well known to have toxic effects, especially for embryos and small children. Even in small doses, lead poisoning may lead to permanent intelligence deficiencies and concentration difficulties.